Myasthenia gravis – Etiologia i przyczyny

Myasthenia gravis
Etiologia i przyczyny

Myasthenia gravis (MG) to przewlekła choroba autoimmunologiczna charakteryzująca się osłabieniem mięśni szkieletowych, wynikająca z produkcji przeciwciał przeciwko receptorom acetylocholiny (AChR) u około 85% pacjentów, białku MuSK lub LRP4, co prowadzi do zaburzenia transmisji nerwowo-mięśniowej. Grasica odgrywa kluczową rolę w patogenezie MG, z nieprawidłowościami występującymi u 75% chorych, w tym hiperplazją u 65% i thymomą u 10-15%, przy czym 30-50% pacjentów z thymomą rozwija MG. Czynniki genetyczne, zwłaszcza określone genotypy HLA (np. HLA-B8, HLA-DR3), predysponują do choroby, a około 5% pacjentów ma bliskiego krewnego z MG. Współistnienie innych chorób autoimmunologicznych występuje u 5-10% chorych, a u 25% pacjentów z MG diagnozuje się dodatkowe schorzenia autoimmunologiczne, takie jak nadczynność tarczycy (38%), RZS czy toczeń rumieniowaty układowy.

Etiologia Myasthenia gravis

Myasthenia gravis (MG) jest przewlekłą chorobą autoimmunologiczną, charakteryzującą się osłabieniem i męczliwością mięśni szkieletowych. Choroba ta występuje, gdy układ odpornościowy organizmu błędnie atakuje własne tkanki, w tym wypadku złącza nerwowo-mięśniowe. Pomimo intensywnych badań, dokładna przyczyna rozwoju MG pozostaje nie w pełni poznana, ale zidentyfikowano kilka kluczowych czynników wpływających na jej patogenezę.¹²

Mechanizm autoimmunologiczny

W przebiegu myasthenia gravis układ odpornościowy wytwarza przeciwciała, które atakują, blokują lub niszczą receptory znajdujące się w złączu nerwowo-mięśniowym, gdzie nerwy łączą się z mięśniami. Głównym mechanizmem odpowiedzialnym za rozwój objawów MG jest zakłócenie komunikacji między nerwami a mięśniami.¹²

U około 85% pacjentów z MG występują przeciwciała skierowane przeciwko receptorom acetylocholiny (AChR). Acetylocholina jest neuroprzekaźnikiem uwalnianym przez zakończenia nerwowe, który normalnie wiąże się z receptorami na powierzchni komórek mięśniowych, powodując skurcz mięśni. W myasthenia gravis przeciwciała przeciwko AChR blokują, zmieniają lub niszczą te receptory, zmniejszając liczbę dostępnych miejsc receptorowych dla acetylocholiny. W rezultacie mięśnie otrzymują mniej sygnałów nerwowych, co prowadzi do osłabienia mięśni.¹²³

U niektórych pacjentów z MG, którzy nie mają przeciwciał przeciwko AChR, występują przeciwciała przeciwko białku zwanemu kinaza tyrozynowa swoista dla mięśni (MuSK). MuSK jest białkiem, które pomaga w formowaniu złącza nerwowo-mięśniowego. Przeciwciała skierowane przeciwko temu białku mogą również prowadzić do rozwoju myasthenia gravis.¹²

Nowsze badania zidentyfikowały również przeciwciała przeciwko innym białkom zaangażowanym w formowanie i utrzymywanie złącza nerwowo-mięśniowego, takim jak białko 4 związane z receptorem lipoproteiny o niskiej gęstości (LRP4), które mogą przyczyniać się do rozwoju choroby u niektórych pacjentów.¹²³

Rola grasicy

Grasica, gruczoł będący częścią układu odpornościowego, znajdujący się w górnej części klatki piersiowej pod mostkiem, odgrywa istotną rolę w patogenezie myasthenia gravis. Naukowcy uważają, że grasica może wyzwalać lub podtrzymywać produkcję przeciwciał, które blokują receptor acetylocholiny.¹²

Około 75% pacjentów z MG ma nieprawidłowości grasicy. U około 65% pacjentów występuje przerost grasicy (hiperplazja grasicy), a u 10-15% rozwija się guz grasicy (thymoma). Badacze uważają, że nieprawidłowa grasica może dawać błędne instrukcje rozwijającym się komórkom układu odpornościowego, co ostatecznie prowadzi do ataku układu odpornościowego na własne komórki i tkanki oraz produkcji przeciwciał przeciwko receptorom acetylocholiny.¹²³

U pacjentów z guzem grasicy (thymoma) ryzyko rozwoju MG jest znacznie wyższe – około 30-50% pacjentów z thymoma rozwija również myasthenia gravis.¹

Czynniki genetyczne

Chociaż myasthenia gravis nie jest uważana za chorobę dziedziczną w klasycznym sensie (nie jest bezpośrednio przekazywana od rodziców do dzieci), istnieją dowody na to, że czynniki genetyczne mogą przyczyniać się do podatności na tę chorobę.¹²

Wykazano związek MG z określonymi genotypami ludzkich antygenów leukocytarnych (HLA), takimi jak HLA-B8, HLA-DR3, HLA-A1, HLA-A3, HLA-B7 i HLA-DQw2. Osoby z tymi genotypami HLA mogą mieć genetyczną predyspozycję do chorób autoimmunologicznych, w tym myasthenia gravis.¹²³

Badania bliźniąt i rodzin konsekwentnie wykazują podwyższone wskaźniki występowania MG i innych zaburzeń autoimmunologicznych, co sugeruje, że genetyczna podatność odgrywa rolę w rozwoju choroby. Szacuje się, że około 5% pacjentów z MG ma bliskiego krewnego z tą chorobą, co sugeruje pewien bezpośredni wpływ genetyczny na rozwój MG.¹²

Ponadto, u około 5-10% osób z MG występuje inna choroba autoimmunologiczna, która pojawiła się przed lub po wystąpieniu MG, co również wskazuje na genetyczną predyspozycję do autoimmunizacji.¹

Czynniki środowiskowe i wyzwalające

Badacze uważają, że rozwój myasthenia gravis może być wynikiem kombinacji czynników genetycznych i środowiskowych. Czynniki wyzwalające mogą obejmować:¹²

Infekcje – wirusowe lub bakteryjne zakażenia mogą wyzwalać lub przyczyniać się do wystąpienia objawów MG. Niektóre białka wirusowe lub bakteryjne mogą naśladować białka własne organizmu (takie jak AChR), stymulując układ odpornościowy do nieświadomego ataku na własne białko. Szczególnie zakażenia wirusem Epsteina-Barr (EBV) i cytomegalowirusem (CMV) zostały powiązane ze zwiększonym ryzykiem rozwoju MG.¹²³
Szczepienia – w rzadkich przypadkach mogą być zaangażowane w wystąpienie MG.¹²
Operacje – mogą wyzwalać objawy MG lub powodować zaostrzenie istniejących objawów.¹²
Stres – zarówno fizyczny, jak i emocjonalny, może wpływać na nasilenie objawów.¹²
Ekspozycja na pestycydy – niektóre badania sugerują, że narażenie na pestycydy, takie jak związki fosforoorganiczne i karbaminiany, może zakłócać funkcjonowanie złącza nerwowo-mięśniowego w organizmie.¹
Niedobory żywieniowe – takie jak niedobór żelaza czy witaminy D, które mogą osłabiać mięśnie i czynić je bardziej podatnymi na atak ze strony układu odpornościowego.¹

Leki i substancje wyzwalające lub zaostrzające objawy

Niektóre leki mogą wywoływać lub zaostrzać objawy myasthenia gravis. Do tych leków należą:¹²³

Antybiotyki – zwłaszcza aminoglikozydy, polimyksyny, ciprofloksacyna, erytromycyna i ampicylina.¹²
Beta-blokery – mogą nasilać osłabienie mięśni.¹²
Leki przeciwarytmiczne – takie jak chinidyna i prokainamid.¹²
Leki przeciwpadaczkowe – np. fenytoina (Dilantin).¹
Niektóre środki znieczulające.¹
Penicylamina – około 1-2% osób leczonych długoterminowo penicylaminą może rozwinąć MG lub wytworzyć niskie stężenia przeciwciał przeciwko AChR.¹
Statyny – leki obniżające poziom cholesterolu we krwi, które mogą w rzadkich przypadkach nasilać objawy myasthenia gravis.¹²
Inhibitory punktów kontrolnych immunologicznych – stosowane w leczeniu niektórych nowotworów, mogą prowadzić do de novo indukcji lub pogorszenia zaburzeń autoimmunologicznych.¹²

Czynniki hormonalne i płciowe

Hormony i płeć również odgrywają rolę w rozwoju i przebiegu myasthenia gravis. Choroba ma tendencję do występowania w dwóch głównych grupach wiekowych, z różnicami płciowymi:¹²

Kobiety w wieku 20-30 lat mają większe prawdopodobieństwo rozwoju MG.¹²
Mężczyźni w wieku 60-70 lat stanowią drugą grupę o podwyższonym ryzyku.¹²

Wahania hormonalne związane z ciążą i cyklem miesiączkowym mogą wpływać na nasilenie objawów MG u kobiet.¹²

Ponadto, istnieje związek między MG a chorobami tarczycy, szczególnie nadczynnością tarczycy. Nadczynność tarczycy występuje u około 38% pacjentów z MG i ma szczególny związek z oczną postacią myasthenia gravis.¹²

Współwystępowanie innych chorób autoimmunologicznych

Osoby z myasthenia gravis mają zwiększone ryzyko rozwoju innych chorób autoimmunologicznych. Około 25% pacjentów z MG ma również inną chorobę autoimmunologiczną, w tym:¹²

Choroby tarczycy (w tym nadczynność tarczycy)¹²
Reumatoidalne zapalenie stawów¹²
Toczeń rumieniowaty układowy¹²
Choroba Addisona¹
Zespół Guillaina-Barrégo¹
Młodzieńcze reumatoidalne zapalenie stawów¹
Zapalenie skórno-mięśniowe¹
Zapalenie wielomięśniowe¹

Specjalne formy myasthenia gravis

Istnieją również specyficzne formy myasthenia gravis z odmienną etiologią:¹²

Noworodkowa myasthenia gravis – występuje, gdy matki z MG przekazują przeciwciała płodowi podczas ciąży. Przeciwciała przechodzą przez łożysko do płodu, powodując przejściowe osłabienie mięśni u noworodka. Objawy zwykle ustępują w ciągu kilku tygodni po urodzeniu, gdy przeciwciała matki ulegają degradacji.¹²³
Wrodzona myasthenia gravis (zespół miasteniczny wrodzony) – rzadka, dziedziczna forma myasthenia gravis, spowodowana defektem genetycznym w złączu nerwowo-mięśniowym. W przeciwieństwie do typowej MG, nie jest to choroba autoimmunologiczna, ale wynika z wadliwych genów.¹²
Seronegatywna myasthenia gravis – występuje u pacjentów, u których nie wykryto określonych przeciwciał przeciwko AChR, MuSK lub LRP4. Badacze uważają, że ten typ MG nadal wynika z problemu z autoimmunizacją, ale zaangażowane przeciwciała nie zostały jeszcze zidentyfikowane.¹²

Czynniki nasilające objawy myasthenia gravis

U pacjentów z rozpoznaną myasthenia gravis istnieje wiele czynników, które mogą nasilać objawy choroby:¹²

Zmęczenie i wysiłek fizyczny¹²
Choroba lub infekcja – szczególnie infekcje dróg oddechowych¹²
Zabiegi chirurgiczne¹²
Stres emocjonalny i fizyczny¹²
Wahania hormonalne – związane z ciążą i miesiączką¹²
Ekspozycja na ekstremalne ciepło¹
Przyjmowanie określonych leków (omówionych wcześniej)¹²

Podsumowanie etiologii myasthenia gravis

Myasthenia gravis jest złożoną chorobą autoimmunologiczną, której etiologia obejmuje wiele czynników. Głównym mechanizmem patogenetycznym jest produkcja przeciwciał, które atakują receptory acetylocholiny lub inne białka w złączu nerwowo-mięśniowym, prowadząc do zaburzenia transmisji sygnałów nerwowych i osłabienia mięśni.¹²

Chociaż dokładna przyczyna rozwoju MG pozostaje niejasna, badania wskazują na istotną rolę nieprawidłowości grasicy, czynników genetycznych, środowiskowych, hormonalnych oraz współistniejących chorób autoimmunologicznych. Lepsze zrozumienie tych czynników może prowadzić do rozwoju bardziej skutecznych metod leczenia i potencjalnie do zapobiegania tej chorobie w przyszłości.¹²³

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Materiały źródłowe

#1 Myasthenia Gravis | National Institute of Neurological Disorders and Stroke
https://www.ninds.nih.gov/health-information/disorders/myasthenia-gravis
Myasthenia gravis is an autoimmune disease, which means that the body’s defense system mistakenly attacks healthy cells or proteins needed for normal functioning. […] Myasthenia gravis is caused by an error in how nerve signals are sent to muscles, specifically when communication between the nerve and muscle is interrupted at the neuromuscular junction. […] In myasthenia gravis, antibodies (immune proteins produced by the body’s immune system) block, alter, or destroy the receptors for acetylcholine at the neuromuscular junction, which prevents the muscle from contracting. This is most often caused by antibodies to the acetylcholine receptor itself, but antibodies to other proteins, such as MuSK (Muscle-Specific Kinase) protein, also can impair transmission at the neuromuscular junction.
#1 Myasthenia gravis – Symptoms and causes – Mayo Clinic
https://www.mayoclinic.org/diseases-conditions/myasthenia-gravis/symptoms-causes/syc-20352036
Myasthenia gravis (my-us-THEE-nee-uh GRAY-vis) causes muscles under your voluntary control to feel weak and get tired quickly. This happens when the communication between nerves and muscles breaks down. […] There’s no cure for myasthenia gravis. Treatment can help with symptoms. […] In myasthenia gravis, certain receptor sites are blocked or destroyed, causing muscle weakness. […] In myasthenia gravis, the immune system makes antibodies that block or destroy many of your muscles’ receptor sites for a neurotransmitter called acetylcholine (as-uh-teel-KOH-leen). With fewer receptor sites available, your muscles receive fewer nerve signals. This causes weakness. […] Antibodies also can block a protein called muscle-specific receptor tyrosine kinase (TIE-roh-seen KIE-nays), sometimes referred to as MuSK. This protein helps form the nerve-muscle junction. Antibodies against this protein can lead to myasthenia gravis.
#1 Myasthenia gravis // Middlesex Health
https://middlesexhealth.org/learning-center/diseases-and-conditions/myasthenia-gravis
Your nerves communicate with your muscles by releasing chemicals, called neurotransmitters, that fit into places on the muscle cells, called receptor sites, at the nerve-muscle junction. […] In myasthenia gravis, the immune system makes antibodies that block or destroy many of your muscles’ receptor sites for a neurotransmitter called acetylcholine (as-uh-teel-KOH-leen). With fewer receptor sites available, your muscles receive fewer nerve signals. This causes weakness. […] Antibodies also can block a protein called muscle-specific receptor tyrosine kinase (TIE-roh-seen KIE-nays), sometimes referred to as MuSK. This protein helps form the nerve-muscle junction. Antibodies against this protein can lead to myasthenia gravis. […] Antibodies against another protein, called lipoprotein-related protein 4 (LRP4), can play a part in this condition. Research studies have found other antibodies and the number of antibodies involved will likely grow over time.
#1 Myasthenia gravis – Symptoms and causes – Mayo Clinic
https://www.mayoclinic.org/diseases-conditions/myasthenia-gravis/symptoms-causes/syc-20352036
The thymus gland, a part of your immune system situated in the upper chest beneath the breastbone, may trigger or maintain the production of antibodies that result in the muscle weakness. […] Researchers believe that the thymus gland makes or helps produce the antibodies that block acetylcholine. […] Rarely, mothers with myasthenia gravis have children who are born with myasthenia gravis. This is called neonatal myasthenia gravis. […] Some children are born with a rare, hereditary form of myasthenia gravis, called congenital myasthenic syndrome. […] Factors that can make myasthenia gravis worse include: Fatigue, Illness or infection, Surgery, Stress, Some medicines such as beta blockers, quinidine gluconate, quinidine sulfate, quinine (Qualaquin), phenytoin (Dilantin), certain anesthetics and some antibiotics, Pregnancy, Menstrual periods.
#1 Causes/Inheritance – Myasthenia Gravis (MG) – Diseases | Muscular Dystrophy Association
https://www.mda.org/disease/myasthenia-gravis/causes-inheritance
IstniejÄ rÃ³wnieÅ¼ dowody, Å¼e gruczoÅ ukÅadu odpornoÅciowego zwany grasicy odgrywa rolÄ w MG. […] GruczoÅ grasicy, maÅy gruczoÅ w gÃ³rnej czÄÅci klatki piersiowej, wydaje siÄ odgrywaÄ rolÄ w MG. OkoÅo 15% osÃ³b z MG ma guz grasicy, zwany tymomÄ, a kolejne 75% ma nieprawidÅowoÅci grasicy, stan zwany hiperplazjÄ grasicy. […] ChociaÅ¼ MG i inne choroby autoimmunologiczne nie sÄ dziedziczne, wydaje siÄ, Å¼e podatnoÅÄ genetyczna odgrywa rolÄ. […] Wydaje siÄ prawdopodobne, Å¼e czynniki genetyczne rÃ³wnieÅ¼ przyczyniajÄ siÄ do patogenezy MG. […] WiÄkszoÅÄ badaÅ sugeruje, Å¼e jeÅli ktoÅ ma krewnego z chorobÄ autoimmunologicznÄ, ryzyko zachorowania na chorobÄ autoimmunologicznÄ wzrasta, im bliÅ¼szy krewny, tym wyÅ¼sze ryzyko. […] Szacuje siÄ, Å¼e 5% do 10% osÃ³b z MG ma innÄ chorobÄ autoimmunologicznÄ, ktÃ³ra pojawiÅa siÄ przed lub po wystÄpieniu MG.
#1 Myasthenia Gravis: Causes, Symptoms, and Treatment | Doctor
https://patient.info/doctor/myasthenia-gravis-pro
Myasthenia gravis causes (aetiology) In most patients, IgG1-dominant antibodies to acetylcholine receptors cause fatigable weakness of skeletal muscles. In the rest, a variable proportion possesses antibodies to MuSK. About 15% of patients with MG have a thymoma and 30-50% of patients with thymoma also have MG. The condition can sometimes be inherited, although there is a predisposition for autoimmune diseases to run in families. Online Mendelian Inheritance in Man (OMIM) lists many entries under MG, although most are myasthenic syndromes. Just one is called myasthenia gravis. This suggests an association of MG with HLA B8 and DR3. In terms of underlying genetic abnormalities, work is ongoing. […] There is an association between MG and other autoimmune diseases in 25%. They include thyroid disease, dermatomyositis, polymyositis, systemic lupus erythematosus, Addison’s disease, Guillain-Barr syndrome and juvenile rheumatoid arthritis.
#1 What Causes Myasthenia Gravis? 5 Risk Factors To Know | MGteam
https://www.mgteam.com/resources/what-causes-myasthenia-gravis
Myasthenia gravis is an autoimmune neuromuscular disorder caused by the immune system attacking the muscles. Although doctors and researchers understand how myasthenia gravis develops, theyre not quite sure why it occurs in some people and not others. Unfortunately, not much is known about the exact cause of myasthenia gravis, but a handful of risk factors play a role. […] Although its known that autoantibodies are involved in myasthenia gravis, the reason they develop in the first place is less clear. Doctors and researchers believe certain risk factors including genetics, age, gender, and environment may all contribute to developing myasthenia gravis. […] Myasthenia gravis and other autoimmune diseases arent hereditary (directly passed down from parents to children), but genetics still seem to play a factor.
#1 Myasthenia Gravis: Practice Essentials, Background, Anatomy
https://emedicine.medscape.com/article/1171206-overview
Myasthenia gravis (MG) is idiopathic in most patients. Although the main cause behind its development remains speculative, the end result is a derangement of immune system regulation. MG is clearly an autoimmune disease in which the specific antibody has been characterized completely. In as many as 90% of generalized cases, IgG to AChR is present. […] Patients who are negative for anti-AChR antibodies may be seropositive for antibodies against MuSK. Muscle biopsies of these patients show myopathic features with prominent mitochondrial abnormalities, as opposed to the neurogenic features and atrophy frequently found in MG patients positive for anti-AChR. The mitochondrial impairment could explain the oculobulbar involvement in anti-MuSKpositive MG. […] Numerous findings have been associated with MG. For example, people with certain human leukocyte antigen (HLA) types have a genetic predisposition to autoimmune diseases. The histocompatibility complex profile includes HLA-A1, -A3, -B7, -B8, -DRw3, and -DQw2 (though these have not been shown to be associated with the strictly ocular form of MG). However, HLA genotyping is not routinely used in the evaluation of patients suspected to have MG.
#1
https://www.jci.org/articles/view/179742
Evidence in both humans and animal models (experimental autoimmune MG [EAMG]) has demonstrated the importance of complement activation in mediating disease in patients with AChR antibody-positive MG. […] Upward of 10 percent of patients may not have detectable circulating autoantibody against AChR or MuSK. […] Substantial advancements in understanding MG pathophysiology have led to growing recognition of various mechanisms contributing to disease development in different patient groups. […] The clinical categories of ocular and generalized MG can be divided further based on autoantibody status, age, and thymic pathology. […] Much like other autoimmune conditions, a genetic predisposition contributes to development, with twin and family studies consistently demonstrating elevated prevalence rates of MG and other autoimmune disorders.
#1 Myasthenia Gravis Causes: Factors That Contribute to This Condition
https://ameripharmaspecialty.com/myasthenia-gravis/myasthenia-gravis-causes-factors-that-lead-to-this-condition/
According to the Myasthenia Gravis Foundation of America, around 36,000 to 70,000 people have been diagnosed with myasthenia gravis (MG) in the United States alone. […] Myasthenia gravis is an autoimmune neurological disorder that causes severe muscle weakness, which can later lead to respiratory failure as the muscles that function to keep the airway open are compromised. […] Though the exact cause that triggers this neurological condition remains unclear, it is believed that a combination of genetic, immunological, environmental, and physiological factors is involved in the onset of myasthenia gravis. […] Several common factors, like age, thymus gland irregularities, immune attack, infection (viral or bacterial), immunization, or rarely surgery, can trigger the onset of myasthenia gravis. However, among all factors, immune dysfunction plays a significant role in the onset and progression of myasthenia gravis.
#1 Causes/Inheritance – Myasthenia Gravis (MG) – Diseases | Muscular Dystrophy Association
https://www.mda.org/disease/myasthenia-gravis/causes-inheritance
Normalnie (A), ukÅad odpornoÅciowy uwalnia przeciwciaÅa, aby zaatakowaÄ obce najeÅºdÅºcÃ³w, takich jak bakterie. W chorobach autoimmunologicznych (B), przeciwciaÅa bÅÄdnie atakujÄ wÅasne tkanki osoby. W miastenii gravis atakujÄ i uszkadzajÄ komÃ³rki miÄÅniowe. […] W wiÄkszoÅci przypadkÃ³w MG, ukÅad odpornoÅciowy celuje w receptor acetylocholiny, biaÅko na komÃ³rkach miÄÅniowych, ktÃ³re jest wymagane do unerwienia miÄÅni i ostatecznie skurczu. […] Myasthenia gravis wystÄpuje, gdy ukÅad odpornoÅciowy wytwarza przeciwciaÅa, ktÃ³re niszczÄ receptor ACh (AChR), miejsce dokujÄce dla chemicznego nerwu acetylocholiny (ACh). […] OkoÅo 85% osÃ³b z MG ma przeciwciaÅa przeciwko receptorowi ACh (AChR) we krwi. […] Naukowcy nie wiedzÄ, co wywoÅuje wiÄkszoÅÄ reakcji autoimmunologicznych, ale majÄ kilka teorii. JednÄ z moÅ¼liwoÅci jest to, Å¼e niektÃ³re biaÅka wirusowe lub bakteryjne naÅladujÄ „biaÅka wÅasne” w organizmie (takie jak AChR), stymulujÄc ukÅad odpornoÅciowy do nieÅwiadomego ataku na biaÅko wÅasne.
#1 Myasthenia Gravis – StatPearls – NCBI Bookshelf
https://www.ncbi.nlm.nih.gov/books/NBK559331/
Myasthenia gravis, similar to other autoimmune disorders, occurs in genetically susceptible individuals. Precipitating factors include conditions like infections, immunization, surgeries, and drugs. […] The commonly implicated proteins in the NMJ against which autoantibodies are produced include the nicotinic acetylcholine receptors (n-AChR’s), muscle-specific kinase (MuSK), and lipoprotein-related protein 4 (LPR4). AgrinLRP4MuSK protein complex is essential for the formation and maintenance of NMJ, including the distribution and clustering of the AChR. Approximately 10% of patients with MG have a thymoma, and it is implicated in the production of autoantibodies.
#1 What Causes Myasthenia Gravis | Pompa Program
https://pompaprogram.com/what-causes-myasthenia-gravis/
Exposure to certain pesticides, such as organophosphates and carbamates, can interfere with the functioning of the neuromuscular junction in the body. This is because these types of chemicals affect how nerve signals interact with muscle fibers, leading to muscle weakness. Additionally, some studies have indicated that those who are exposed to a variety of different chemicals are at an increased risk of developing myasthenia gravis. […] Individuals with Myasthenia gravis were found to have an iron deficiency, which can weaken the muscles and make them more susceptible to attack from the immune system. Iron deficiency can also reduce levels of acetylcholine, a neurotransmitter that helps with muscle contraction, which can further weaken the muscles and lead to myasthenia gravis. […] Evidence suggests that low levels of vitamin D play a role in the development and progression of Myasthenia Gravis. Vitamin D helps regulate nerve-muscle communication and the immune system, both of which can be disrupted in myasthenia gravis.
#1 Myasthenia Gravis: Practice Essentials, Background, Anatomy
https://emedicine.medscape.com/article/1171206-overview
Sensitization to a foreign antigen that has cross-reactivity with the nicotinic ACh receptor has been proposed as a cause of myasthenia gravis, but the triggering antigen has not yet been identified. […] Various drugs may induce or exacerbate symptoms of MG, including the following: Antibiotics (eg, aminoglycosides, polymyxins, ciprofloxacin, erythromycin, and ampicillin) […] Thymic abnormalities are common: Of patients with MG, 75% have thymic disease, 85% have thymic hyperplasia, and 10-15% have thymoma. Extrathymic tumors may include small cell lung cancer and Hodgkin disease. […] Hyperthyroidism is present in 38% of patients with MG and has a particular association with ocular MG.
#1 Myasthenia gravis – Wikipedia
https://en.wikipedia.org/wiki/Myasthenia_gravis
Myasthenia gravis is an autoimmune disease of the neuromuscular junction which results from antibodies that block or destroy nicotinic acetylcholine receptors (AChR) at the junction between the nerve and muscle. […] Most cases are due to immunoglobulin G1 (IgG1) and IgG3 antibodies that attack AChR in the postsynaptic membrane, causing complement-mediated damage and muscle weakness. […] Rarely, an inherited genetic defect in the neuromuscular junction results in a similar condition known as congenital myasthenia. […] About 1-2% of individuals treated long term with penicillamine develop MG and/or develop low concentrations of antibodies to AChR. […] Their MG is often mild and predominantly ocular MG, becomes evident usually 6-7 months (range one month to 8 years) after starting the drug, and goes into complete remission in 70% of the cases within 6-10 months after discontinuing the drug.
#1 Myasthenia Gravis | National Institute of Neurological Disorders and Stroke
https://www.ninds.nih.gov/health-information/disorders/myasthenia-gravis
The thymus gland controls immune function and may be associated with myasthenia gravis. […] Scientists believe the thymus gland may give incorrect instructions to developing immune cells, ultimately causing the immune system to attack its own cells and tissues and produce acetylcholine receptor antibodies. […] Several common medications, including statins, which are prescribed to help lower cholesterol, may rarely worsen myasthenia gravis.
#1 Myasthenia gravis – Wikipedia
https://en.wikipedia.org/wiki/Myasthenia_gravis
Statins are drugs that lower blood cholesterol levels in order to reduce the risk of developing a cardiovascular disease due to atherosclerosis. […] In a 2019 review of 169 patients who were reported to develop myasthenia gravis or had worsened myasthenia gravis symptoms while taking a statin, 138 had developed generalized myasthenia gravis, 13 had developed ocular myasthenia gravis, and 18 had worsening of their myasthenia gravis. […] Immune checkpoint inhibitors promote certain types of autoimmune responses by blocking checkpoint pathways that inhibit these responses. […] They are used to treat cancers that promote their own growth and spread by stimulating checkpoint pathways.
#1 Myasthenia Gravis Causes | Stanford Health Care
https://stanfordhealthcare.org/medical-conditions/brain-and-nerves/myasthenia-gravis/causes.html
Myasthenia gravis is an autoimmune disease. Experts do not know what triggers the immune system dysfunction and they do not believe it is an inherited condition. […] The symptoms of myasthenia gravis may occur at any age. They are more common in young adults and those older than age 50. Women tend to get myasthenia gravis at an earlier age than men.
#1 Myasthenia Gravis: Causes, Genetic Factors, and Risks
https://www.verywellhealth.com/myasthenia-gravis-causes-5112660
Unlike many other types of disorders, MG is not considered a disease that is directly inherited, but rather, there may be a genetic predisposition for autoimmune diseases. […] The disease is known to cause a high prevalence of heart problems in 10% to 15% of those with MG who also have thymoma. […] According to a 2014 study, the heart muscle is a target for autoimmune inflammation in MG. […] General risk factors found to increase the chance of a person getting MG include: Being a woman between the ages of 20 to 30, Being a man between the ages of 60 to 70, Having specific genetic markers called HLA-B8 or DR3, Neonates (newborn infants) with mothers who have abnormal antibodies that have entered the baby’s body via the placenta during pregnancy.
#1 Myasthenia Gravis – UF Health
https://ufhealth.org/conditions-and-treatments/myasthenia-gravis
Myasthenia gravis is an autoimmune disorder. An autoimmune disorder occurs when the immune system mistakenly attacks healthy tissue. Antibodies may be produced when the immune system mistakenly considers healthy tissue to be a harmful substance, such as in the case of myasthenia gravis. […] In some cases, myasthenia gravis is linked to tumors of the thymus (an organ of the immune system). […] People with myasthenia gravis are at higher risk for other autoimmune disorders, such as thyrotoxicosis, rheumatoid arthritis, and systemic lupus erythematosus (lupus).
#1 Myasthenia gravis // Middlesex Health
https://middlesexhealth.org/learning-center/diseases-and-conditions/myasthenia-gravis
Some people have myasthenia gravis that isn’t caused by antibodies blocking acetylcholine, MuSK or LRP4. This type of myasthenia gravis is called seronegative myasthenia gravis, also known as antibody-negative myasthenia gravis. In general, researchers believe that this type of myasthenia gravis still comes from a problem with autoimmunity, but the antibodies involved just can’t be found yet. […] The thymus gland, a part of your immune system situated in the upper chest beneath the breastbone, may trigger or maintain the production of antibodies that result in the muscle weakness. […] Researchers believe that the thymus gland makes or helps produce the antibodies that block acetylcholine. […] Rarely, mothers with myasthenia gravis have children who are born with myasthenia gravis. This is called neonatal myasthenia gravis. If treated immediately, children usually recover within two months after birth.
#1 What Causes Myasthenia Gravis? Symptoms
https://www.emedicinehealth.com/what_causes_myasthenia_gravis/article_em.htm
Certain triggers may cause symptoms of myasthenia gravis to worsen, such as: Exposure to extreme heat, Emotional stress, Infection, Systemic illness, Pregnancy, The menstrual cycle. […] Certain drugs may precipitate or worsen myasthenia gravis symptoms, including: Antibiotics, Penicillamine, Beta-blockers, Lithium, Magnesium, Procainamide, Verapamil, Quinidine, Chloroquine, Prednisone, Timolol, Anticholinergics, Neuromuscular blocking agents, Nitrofurantoin, Cancer immunotherapy.
#1 Myasthenia Gravis: Causes, Risk Factors, Diagnosis, Treatment and Current/Future Research | Scientist.com
https://app.scientist.com/blog/2023/06/08/myasthenia-gravis-causes-risk-factors-diagnosis-treatment-and-current-future-research
Environmental factors, such as viral infections and exposure to certain medications, have been implicated as potential triggers for MG in genetically susceptible individuals. Infections caused by Epstein-Barr virus (EBV) and cytomegalovirus (CMV) have been associated with an increased risk of developing MG. Additionally, certain medications, such as antibiotics (e.g., fluoroquinolones) and beta-blockers, have been reported to trigger MG or exacerbate existing symptoms. […] Furthermore, thymic abnormalities have been associated with MG, particularly thymomas (tumors of the thymus gland) and thymic hyperplasia (overgrowth of thymic tissue). The thymus plays a crucial role in the maturation of immune cells, and aberrations in its structure and function may contribute to the development of autoimmunity in MG. […] While the exact cause of MG remains elusive, the production of autoantibodies targeting acetylcholine receptors or MuSK is a central pathological feature. The interplay between genetic susceptibility, environmental triggers and immune dysregulation contributes to disease development.
#2 Myasthenia Gravis: What It Is, Causes, Symptoms & Treatment
https://my.clevelandclinic.org/health/diseases/17252-myasthenia-gravis-mg
Myasthenia gravis is an autoimmune condition that causes skeletal muscle weakness. […] Myasthenia gravis (autoimmune type) happens when your bodys immune system mistakenly attacks itself. Researchers arent sure why this happens. […] A genetic change causes congenital myasthenia. Antibodies passed from a birth mother to a fetus during pregnancy cause neonatal myasthenia.
#2 Myasthenia Gravis | National Institute of Neurological Disorders and Stroke
https://www.ninds.nih.gov/health-information/disorders/myasthenia-gravis
Myasthenia gravis is an autoimmune disease, which means that the body’s defense system mistakenly attacks healthy cells or proteins needed for normal functioning. […] Myasthenia gravis is caused by an error in how nerve signals are sent to muscles, specifically when communication between the nerve and muscle is interrupted at the neuromuscular junction. […] In myasthenia gravis, antibodies (immune proteins produced by the body’s immune system) block, alter, or destroy the receptors for acetylcholine at the neuromuscular junction, which prevents the muscle from contracting. This is most often caused by antibodies to the acetylcholine receptor itself, but antibodies to other proteins, such as MuSK (Muscle-Specific Kinase) protein, also can impair transmission at the neuromuscular junction.
#2 Myasthenia gravis | Better Health Channel
https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/myasthenia-gravis
Myasthenia gravis is just one of many autoimmune diseases, which include arthritis and type 1 diabetes. Normally, the immune system produces antibodies that recognise foreign things that enter the body, such as bacteria and viruses. This leads to them being destroyed and cleared from the body. In the case of an autoimmune condition, the body’s immune system produces antibodies against things in the body that aren’t foreign. In myasthenia gravis it is the structure at the junction of the nerves and the muscles (the neuromuscular junction) that is attacked. About 85 percent of patients with myasthenia gravis produce antibodies against a protein called the acetylcholine receptor (AChR). This is found at the neuromuscular junction and acts as a receiver for the chemical signal acetylcholine (ACh) that is released from the nerve to tell a muscle to contract. The antibodies bind to the acetylcholine receptors on the surface of the muscle and greatly reduce their ability to receive the chemical signal. As a result, the person experiences muscle weakness, which becomes worse as they repeatedly try to use the same muscle. Many people with myasthenia gravis who don’t have antibodies to the AChR, have antibodies to a protein called muscle-specific kinase (MuSK). This protein helps organise ACh receptors on the muscle cell surface. Research is ongoing to find out what antibody is responsible in the approximately 10 percent of people who don’t have antibodies to AChR or MuSK. Recently, antibodies to a protein called LRP4 were found to be the cause for some of these people. Scientists don’t know what triggers most autoimmune conditions, but they have a few theories. One possibility is that certain viral or bacterial proteins mimic self-proteins in the body (such as AChR), stimulating the immune system to accidentally attack it. There is also evidence that the thymus gland plays a role in myasthenia gravis. About 15 percent of people with myasthenia gravis have a thymic tumour, called a thymoma, and another 65 percent have an overactive thymus, a condition called thymic hyperplasia. When the thymus doesn’t work properly, the immune system might lose some of its ability to distinguish self from non-self, making it more likely to attack the body’s own cells.
#2 Myasthenia gravis (MG) – Muscular Dystrophy UK
https://www.musculardystrophyuk.org/conditions/a-z/myasthenia-gravis/
Some people produce antibodies against a different protein, muscle-specific kinase (MuSK), which also disrupts communication between nerves and muscles, leading to similar muscle weakness. Other rare antibodies such as LRP4 have been found in some people with MG, and there are some people without known antibodies (called seronegative myasthenia gravis). […] Its not clear why this happens. In some cases, the thymus gland in the chest might trigger the abnormal immune response, especially in younger people. Trials have shown that removing the thymus can improve symptoms in younger people with recent MG onset. At least 1 in 10 people with MG have a thymoma, which is usually a benign (non-cancerous) tumour of the thymus gland, although estimates in some populations are much higher.
#2 Myasthenia Gravis | National Institute of Neurological Disorders and Stroke
https://www.ninds.nih.gov/health-information/disorders/myasthenia-gravis
The thymus gland controls immune function and may be associated with myasthenia gravis. […] Scientists believe the thymus gland may give incorrect instructions to developing immune cells, ultimately causing the immune system to attack its own cells and tissues and produce acetylcholine receptor antibodies. […] Several common medications, including statins, which are prescribed to help lower cholesterol, may rarely worsen myasthenia gravis.
#2 Myasthenia Gravis: Practice Essentials, Background, Anatomy
https://emedicine.medscape.com/article/1171206-overview
Sensitization to a foreign antigen that has cross-reactivity with the nicotinic ACh receptor has been proposed as a cause of myasthenia gravis, but the triggering antigen has not yet been identified. […] Various drugs may induce or exacerbate symptoms of MG, including the following: Antibiotics (eg, aminoglycosides, polymyxins, ciprofloxacin, erythromycin, and ampicillin) […] Thymic abnormalities are common: Of patients with MG, 75% have thymic disease, 85% have thymic hyperplasia, and 10-15% have thymoma. Extrathymic tumors may include small cell lung cancer and Hodgkin disease. […] Hyperthyroidism is present in 38% of patients with MG and has a particular association with ocular MG.
#2 Causes/Inheritance – Myasthenia Gravis (MG) – Diseases | Muscular Dystrophy Association
https://www.mda.org/disease/myasthenia-gravis/causes-inheritance
IstniejÄ rÃ³wnieÅ¼ dowody, Å¼e gruczoÅ ukÅadu odpornoÅciowego zwany grasicy odgrywa rolÄ w MG. […] GruczoÅ grasicy, maÅy gruczoÅ w gÃ³rnej czÄÅci klatki piersiowej, wydaje siÄ odgrywaÄ rolÄ w MG. OkoÅo 15% osÃ³b z MG ma guz grasicy, zwany tymomÄ, a kolejne 75% ma nieprawidÅowoÅci grasicy, stan zwany hiperplazjÄ grasicy. […] ChociaÅ¼ MG i inne choroby autoimmunologiczne nie sÄ dziedziczne, wydaje siÄ, Å¼e podatnoÅÄ genetyczna odgrywa rolÄ. […] Wydaje siÄ prawdopodobne, Å¼e czynniki genetyczne rÃ³wnieÅ¼ przyczyniajÄ siÄ do patogenezy MG. […] WiÄkszoÅÄ badaÅ sugeruje, Å¼e jeÅli ktoÅ ma krewnego z chorobÄ autoimmunologicznÄ, ryzyko zachorowania na chorobÄ autoimmunologicznÄ wzrasta, im bliÅ¼szy krewny, tym wyÅ¼sze ryzyko. […] Szacuje siÄ, Å¼e 5% do 10% osÃ³b z MG ma innÄ chorobÄ autoimmunologicznÄ, ktÃ³ra pojawiÅa siÄ przed lub po wystÄpieniu MG.
#2 Myasthenia Gravis: Causes, Genetic Factors, and Risks
https://www.verywellhealth.com/myasthenia-gravis-causes-5112660
The cause of myasthenia gravis (MG) is an autoimmune reaction in which the body’s immune system mistakenly attacks specific proteins in the muscles, causing weakness. A genetic predisposition to autoimmune disorders and certain lifestyle factors contribute to the risk of this disease. […] The specific underlying cause of the abnormal immune response, which occurs in people with MG, is not well known. […] However, studies have discovered a link between people with MG and abnormalities in the form of enlargement of the thymus gland. […] According to Harvard Health, nearly 80% of people with MG have distinct abnormalities of the thymus gland. […] In 5% of those with myasthenia gravis, there is a family member with some type of autoimmune disorder. […] Individuals with MG also have an increased frequency of certain genetically determined human leukocyte antigens (HLAs), suggesting that genetic predisposition may play some role in the development of myasthenia gravis.
#2 Myasthenia gravis symptoms, diagnosis & treatment – TeleMed2U
https://www.telemed2u.com/neurology/myasthenia-gravis
The cause of MG is unknown. It is not contagious or inherited, but is an acquired immunological abnormality. There is no specific gene that causes MG. However, there are specific genes that regulate the immune system. […] MG can occur when your body’s immune system produces antibodies that block or destroy receptor sites on muscles. As electrical impulses travel down a nerve, the nerve releases a neurotransmitter called acetylcholine that binds to receptor sites on the muscle. […] Another type of MG, called seronegative myasthenia gravis or antibody-negative myasthenia gravis, is not caused by specific antibodies blocking receptor sites. However, it’s possible that it’s also caused by a faulty autoimmune function. […] About 3% of patients had a close relative with MG, suggesting a small direct genetic influence to developing MG.
#2 Myasthenia Gravis: Causes, Risk Factors, Diagnosis, Treatment and Current/Future Research | Scientist.com
https://app.scientist.com/blog/2023/06/08/myasthenia-gravis-causes-risk-factors-diagnosis-treatment-and-current-future-research
Environmental factors, such as viral infections and exposure to certain medications, have been implicated as potential triggers for MG in genetically susceptible individuals. Infections caused by Epstein-Barr virus (EBV) and cytomegalovirus (CMV) have been associated with an increased risk of developing MG. Additionally, certain medications, such as antibiotics (e.g., fluoroquinolones) and beta-blockers, have been reported to trigger MG or exacerbate existing symptoms. […] Furthermore, thymic abnormalities have been associated with MG, particularly thymomas (tumors of the thymus gland) and thymic hyperplasia (overgrowth of thymic tissue). The thymus plays a crucial role in the maturation of immune cells, and aberrations in its structure and function may contribute to the development of autoimmunity in MG. […] While the exact cause of MG remains elusive, the production of autoantibodies targeting acetylcholine receptors or MuSK is a central pathological feature. The interplay between genetic susceptibility, environmental triggers and immune dysregulation contributes to disease development.
#2 Myasthenia gravis | Nature Reviews Disease Primers
https://www.nature.com/articles/s41572-019-0079-y
Myasthenia gravis (MG) is an autoimmune disease caused by antibodies against the acetylcholine receptor (AChR), muscle-specific kinase (MuSK) or other AChR-related proteins in the postsynaptic muscle membrane. […] Patients are grouped according to the presence of antibodies, symptoms, age at onset and thymus pathology. […] This article explains the major immunological mechanisms in MG. […] This study clarifies the pathogenetic effect of anti-AChR antibodies. […] This article describes how specific vaccination may be involved in the onset of MG.
#2 Myasthenia gravis – Symptoms and causes – Mayo Clinic
https://www.mayoclinic.org/diseases-conditions/myasthenia-gravis/symptoms-causes/syc-20352036
The thymus gland, a part of your immune system situated in the upper chest beneath the breastbone, may trigger or maintain the production of antibodies that result in the muscle weakness. […] Researchers believe that the thymus gland makes or helps produce the antibodies that block acetylcholine. […] Rarely, mothers with myasthenia gravis have children who are born with myasthenia gravis. This is called neonatal myasthenia gravis. […] Some children are born with a rare, hereditary form of myasthenia gravis, called congenital myasthenic syndrome. […] Factors that can make myasthenia gravis worse include: Fatigue, Illness or infection, Surgery, Stress, Some medicines such as beta blockers, quinidine gluconate, quinidine sulfate, quinine (Qualaquin), phenytoin (Dilantin), certain anesthetics and some antibiotics, Pregnancy, Menstrual periods.
#2
https://www.aao.org/eye-health/diseases/what-is-myasthenia-gravis
Your bodys own immune system blocks the receptors of the muscles leading to the signs and symptoms of myasthenia gravis with antibodies. This interferes with the connection between the chemical that travels from nerve endings to stimulate the muscle receptors. Your muscles need this connection for to work correctly. Without this connection the muscles become weak. […] People with a family history of autoimmune disease or myasthenia gravis may be at greater risk to get the disease. […] Myasthenia gravis can get worse with stress, illness, and fatigue.
#2 What Causes Myasthenia Gravis? Symptoms
https://www.emedicinehealth.com/what_causes_myasthenia_gravis/article_em.htm
Certain triggers may cause symptoms of myasthenia gravis to worsen, such as: Exposure to extreme heat, Emotional stress, Infection, Systemic illness, Pregnancy, The menstrual cycle. […] Certain drugs may precipitate or worsen myasthenia gravis symptoms, including: Antibiotics, Penicillamine, Beta-blockers, Lithium, Magnesium, Procainamide, Verapamil, Quinidine, Chloroquine, Prednisone, Timolol, Anticholinergics, Neuromuscular blocking agents, Nitrofurantoin, Cancer immunotherapy.
#2 Myasthenia gravis – Wikipedia
https://en.wikipedia.org/wiki/Myasthenia_gravis
Statins are drugs that lower blood cholesterol levels in order to reduce the risk of developing a cardiovascular disease due to atherosclerosis. […] In a 2019 review of 169 patients who were reported to develop myasthenia gravis or had worsened myasthenia gravis symptoms while taking a statin, 138 had developed generalized myasthenia gravis, 13 had developed ocular myasthenia gravis, and 18 had worsening of their myasthenia gravis. […] Immune checkpoint inhibitors promote certain types of autoimmune responses by blocking checkpoint pathways that inhibit these responses. […] They are used to treat cancers that promote their own growth and spread by stimulating checkpoint pathways.
#2
https://www.jci.org/articles/view/179742
Viral infection has been posited for decades to be a contributor to MG, with thus far limited support. […] Late-onset MG occurs in the context of immune system aging, which is associated with reduced ability to fight infections, reduced response to immunization, increased risk of cancer, and increased rates of autoimmunity. […] Approximately 10% of patients with MG, nearly all of whom have AChR antibodies, have a paraneoplastic form of the disease triggered by the thymoma. […] The development of immune checkpoint inhibitors (ICIs) has led to dramatic benefits for patients with treatment-resistant malignancy, but the unrestrained activation of the immune system has led to de novo induction or worsening of autoimmune disorders in at least 20% of patients depending on the agent and neoplasm.
#2 Myasthenia Gravis: Causes, Genetic Factors, and Risks
https://www.verywellhealth.com/myasthenia-gravis-causes-5112660
Unlike many other types of disorders, MG is not considered a disease that is directly inherited, but rather, there may be a genetic predisposition for autoimmune diseases. […] The disease is known to cause a high prevalence of heart problems in 10% to 15% of those with MG who also have thymoma. […] According to a 2014 study, the heart muscle is a target for autoimmune inflammation in MG. […] General risk factors found to increase the chance of a person getting MG include: Being a woman between the ages of 20 to 30, Being a man between the ages of 60 to 70, Having specific genetic markers called HLA-B8 or DR3, Neonates (newborn infants) with mothers who have abnormal antibodies that have entered the baby’s body via the placenta during pregnancy.
#2 What Causes Myasthenia Gravis? 5 Risk Factors To Know | MGteam
https://www.mgteam.com/resources/what-causes-myasthenia-gravis
HLA genes can also play a role in the type of autoantibodies you develop in myasthenia gravis. […] Your age and gender can also influence your chances of developing myasthenia gravis. […] Another known risk factor for myasthenia gravis is race or ethnicity. […] Roughly three-quarters of people with myasthenia gravis have an overactive or abnormally large thymus (known as thymic hyperplasia). […] Researchers believe that exposure to certain environmental factors can trigger myasthenia gravis in people with underlying genetic risk factors.
#2 What Causes Myasthenia Gravis | Pompa Program
https://pompaprogram.com/what-causes-myasthenia-gravis/
Viral infections like hepatitis C, Epstein-Barr virus herpes simplex virus, West Nile Virus, Influenza A, and COVID-19 are all linked with Myasthenia Gravis. […] Myasthenia Gravis can be caused by other autoimmune conditions. These include Autoimmune Thyroiditis, Systemic Lupus Erythematosus (SLE), Sjogrenâs Syndrome, and Rheumatoid Arthritis (RA). Each of these diseases causes the body to produce autoantibodies that attack its own healthy tissues. […] People with thyroid conditions, specifically hyperthyroidism (an overactive thyroid) are at an increased risk for developing myasthenia gravis. In patients with hyperthyroidism, the immune system is overactive and produces antibodies that attack the nerve cells in the neuromuscular junction. This can lead to muscle weakness and fatigue. In addition, some studies suggest that hyperthyroidism may increase the risk of developing myasthenia gravis.
#2 Myasthenia Gravis: Causes, Symptoms, and Treatment | Doctor
https://patient.info/doctor/myasthenia-gravis-pro
Myasthenia gravis causes (aetiology) In most patients, IgG1-dominant antibodies to acetylcholine receptors cause fatigable weakness of skeletal muscles. In the rest, a variable proportion possesses antibodies to MuSK. About 15% of patients with MG have a thymoma and 30-50% of patients with thymoma also have MG. The condition can sometimes be inherited, although there is a predisposition for autoimmune diseases to run in families. Online Mendelian Inheritance in Man (OMIM) lists many entries under MG, although most are myasthenic syndromes. Just one is called myasthenia gravis. This suggests an association of MG with HLA B8 and DR3. In terms of underlying genetic abnormalities, work is ongoing. […] There is an association between MG and other autoimmune diseases in 25%. They include thyroid disease, dermatomyositis, polymyositis, systemic lupus erythematosus, Addison’s disease, Guillain-Barr syndrome and juvenile rheumatoid arthritis.
#2 Quick Facts:Myasthenia Gravis – Merck Manual Consumer Version
https://www.merckmanuals.com/home/quick-facts-brain-spinal-cord-and-nerve-disorders/peripheral-nerve-disorders/myasthenia-gravis
Myasthenia gravis is an autoimmune disease. Your immune system is your body’s defense system. It helps protect you from illness and infection. But in an autoimmune disease, your immune system attacks parts of your own body. […] In myasthenia gravis, your immune system attacks a receptor in your muscles and the signals to move the muscle cant get through. […] Doctors dont know exactly why this happens, but they think it may involve a problem with the thymus gland. The thymus gland, located in your chest, is part of your immune system. Many people with myasthenia gravis have an unusually large thymus gland or a benign tumor in it. […] You’re more likely to have myasthenia gravis if you have another autoimmune disease, such as: Rheumatoid arthritis, Certain types of hyperthyroidism. […] Myasthenia gravis may start after: An infection, Surgery, Taking certain medicines for high blood pressure, malaria, or unusual heartbeats.
#2 Myasthenia gravis // Middlesex Health
https://middlesexhealth.org/learning-center/diseases-and-conditions/myasthenia-gravis
Some people have myasthenia gravis that isn’t caused by antibodies blocking acetylcholine, MuSK or LRP4. This type of myasthenia gravis is called seronegative myasthenia gravis, also known as antibody-negative myasthenia gravis. In general, researchers believe that this type of myasthenia gravis still comes from a problem with autoimmunity, but the antibodies involved just can’t be found yet. […] The thymus gland, a part of your immune system situated in the upper chest beneath the breastbone, may trigger or maintain the production of antibodies that result in the muscle weakness. […] Researchers believe that the thymus gland makes or helps produce the antibodies that block acetylcholine. […] Rarely, mothers with myasthenia gravis have children who are born with myasthenia gravis. This is called neonatal myasthenia gravis. If treated immediately, children usually recover within two months after birth.
#2 Myasthenia gravis Guide: Causes, Symptoms and Treatment Options
https://www.drugs.com/health-guide/myasthenia-gravis.html
Although myasthenia gravis is not believed to be inherited or contagious, babies born to mothers who have myasthenia gravis have an increased risk of having the disease at birth. This probably is because the baby acquires the antibodies that attack the body’s cells from the mother during gestation. Usually, the baby’s symptoms go away within a few weeks after birth.
#2 Myasthenia gravis
https://womenshealth.gov/a-z-topics/myasthenia-gravis
Myasthenia gravis (MG) is an autoimmune disease that weakens the muscles. […] With MG, normal communication between the nerve and muscle is stopped at the place where nerve endings connect with the muscles they control the nerve-muscle junction. […] In someone with MG, the body’s own immune system makes antibodies that block the binding of acetylcholine to the muscle. […] The thymus gland, part of the immune system, is abnormal in most MG cases. […] Doctors do not fully understand the relationship between the thymus gland and MG. […] A group of rare disorders called congenital myasthenic syndromes (CMS) can produce symptoms similar to MG. […] Unlike MG, these disorders are not autoimmune disorders but are caused by defective genes. […] Researchers are seeking to learn what causes the autoimmune response in MG and to better define the relationship between the thymus gland and MG.
#2 What Is Myasthenia Gravis? Symptoms, Causes, Diagnosis, Treatment, and Prevention
https://www.everydayhealth.com/myasthenia-gravis/guide/
However, some people have what’s called antibody-negative myasthenia gravis, which means the condition hasn’t been caused by antibodies blocking acetylcholine or MuSK. […] In addition, in rare instances, mothers with myasthenia gravis have children who are born with the condition because they pass antibodies blocking acetylcholine or MuSK to the fetus in the womb. […] Myasthenia gravis is an autoimmune disease in which there’s a breakdown in the normal communication between nerves and muscles that occurs at the neuromuscular junction, where your nerve cells connect with the muscles they control.
#2 Myasthenia gravis // Middlesex Health
https://middlesexhealth.org/learning-center/diseases-and-conditions/myasthenia-gravis
Some children are born with a rare, hereditary form of myasthenia gravis, called congenital myasthenic syndrome. […] Factors that can make myasthenia gravis worse include: Fatigue, Illness or infection, Surgery, Stress, Some medicines such as beta blockers, quinidine gluconate, quinidine sulfate, quinine (Qualaquin), phenytoin (Dilantin), certain anesthetics and some antibiotics, Pregnancy, Menstrual periods.
#2 Myasthenia gravis – Symptoms and causes – Mayo Clinic
https://www.mayoclinic.org/diseases-conditions/myasthenia-gravis/symptoms-causes/syc-20352036
Myasthenia gravis (my-us-THEE-nee-uh GRAY-vis) causes muscles under your voluntary control to feel weak and get tired quickly. This happens when the communication between nerves and muscles breaks down. […] There’s no cure for myasthenia gravis. Treatment can help with symptoms. […] In myasthenia gravis, certain receptor sites are blocked or destroyed, causing muscle weakness. […] In myasthenia gravis, the immune system makes antibodies that block or destroy many of your muscles’ receptor sites for a neurotransmitter called acetylcholine (as-uh-teel-KOH-leen). With fewer receptor sites available, your muscles receive fewer nerve signals. This causes weakness. […] Antibodies also can block a protein called muscle-specific receptor tyrosine kinase (TIE-roh-seen KIE-nays), sometimes referred to as MuSK. This protein helps form the nerve-muscle junction. Antibodies against this protein can lead to myasthenia gravis.
#3 Causes/Inheritance – Myasthenia Gravis (MG) – Diseases | Muscular Dystrophy Association
https://www.mda.org/disease/myasthenia-gravis/causes-inheritance
Normalnie (A), ukÅad odpornoÅciowy uwalnia przeciwciaÅa, aby zaatakowaÄ obce najeÅºdÅºcÃ³w, takich jak bakterie. W chorobach autoimmunologicznych (B), przeciwciaÅa bÅÄdnie atakujÄ wÅasne tkanki osoby. W miastenii gravis atakujÄ i uszkadzajÄ komÃ³rki miÄÅniowe. […] W wiÄkszoÅci przypadkÃ³w MG, ukÅad odpornoÅciowy celuje w receptor acetylocholiny, biaÅko na komÃ³rkach miÄÅniowych, ktÃ³re jest wymagane do unerwienia miÄÅni i ostatecznie skurczu. […] Myasthenia gravis wystÄpuje, gdy ukÅad odpornoÅciowy wytwarza przeciwciaÅa, ktÃ³re niszczÄ receptor ACh (AChR), miejsce dokujÄce dla chemicznego nerwu acetylocholiny (ACh). […] OkoÅo 85% osÃ³b z MG ma przeciwciaÅa przeciwko receptorowi ACh (AChR) we krwi. […] Naukowcy nie wiedzÄ, co wywoÅuje wiÄkszoÅÄ reakcji autoimmunologicznych, ale majÄ kilka teorii. JednÄ z moÅ¼liwoÅci jest to, Å¼e niektÃ³re biaÅka wirusowe lub bakteryjne naÅladujÄ „biaÅka wÅasne” w organizmie (takie jak AChR), stymulujÄc ukÅad odpornoÅciowy do nieÅwiadomego ataku na biaÅko wÅasne.
#3 Overview of MG | Myasthenia Gravis Foundation of America
https://myasthenia.org/understanding-mg/overview-mg/
This disruption causes the production of abnormal antibodies, for example, acetylcholine receptor (AChR), muscle-specific tyrosine kinase (MuSK) or low-density lipoprotein receptor-related protein 4 (LRP4) antibodies. […] These abnormal antibodies then affect the signals between the muscle and the nerves at the neuromuscular junction, causing the symptoms of myasthenia gravis, including muscle weakness. […] Another important part of our immune system is a pathway called the complement pathway. […] While the complement pathway is usually helpful, in people with myasthenia gravis this pathway can be overactive, causing changes to the neuromuscular junction. […] These changes reduce the number of acetylcholine receptors, meaning that there are fewer receptors for acetylcholine to bind which also affects the signals between the nerves and the muscles which results in muscle weakness.
#3 Myasthenia gravis | Better Health Channel
https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/myasthenia-gravis
Myasthenia gravis is just one of many autoimmune diseases, which include arthritis and type 1 diabetes. Normally, the immune system produces antibodies that recognise foreign things that enter the body, such as bacteria and viruses. This leads to them being destroyed and cleared from the body. In the case of an autoimmune condition, the body’s immune system produces antibodies against things in the body that aren’t foreign. In myasthenia gravis it is the structure at the junction of the nerves and the muscles (the neuromuscular junction) that is attacked. About 85 percent of patients with myasthenia gravis produce antibodies against a protein called the acetylcholine receptor (AChR). This is found at the neuromuscular junction and acts as a receiver for the chemical signal acetylcholine (ACh) that is released from the nerve to tell a muscle to contract. The antibodies bind to the acetylcholine receptors on the surface of the muscle and greatly reduce their ability to receive the chemical signal. As a result, the person experiences muscle weakness, which becomes worse as they repeatedly try to use the same muscle. Many people with myasthenia gravis who don’t have antibodies to the AChR, have antibodies to a protein called muscle-specific kinase (MuSK). This protein helps organise ACh receptors on the muscle cell surface. Research is ongoing to find out what antibody is responsible in the approximately 10 percent of people who don’t have antibodies to AChR or MuSK. Recently, antibodies to a protein called LRP4 were found to be the cause for some of these people. Scientists don’t know what triggers most autoimmune conditions, but they have a few theories. One possibility is that certain viral or bacterial proteins mimic self-proteins in the body (such as AChR), stimulating the immune system to accidentally attack it. There is also evidence that the thymus gland plays a role in myasthenia gravis. About 15 percent of people with myasthenia gravis have a thymic tumour, called a thymoma, and another 65 percent have an overactive thymus, a condition called thymic hyperplasia. When the thymus doesn’t work properly, the immune system might lose some of its ability to distinguish self from non-self, making it more likely to attack the body’s own cells.
#3
https://www.jci.org/articles/view/179742
Evidence in both humans and animal models (experimental autoimmune MG [EAMG]) has demonstrated the importance of complement activation in mediating disease in patients with AChR antibody-positive MG. […] Upward of 10 percent of patients may not have detectable circulating autoantibody against AChR or MuSK. […] Substantial advancements in understanding MG pathophysiology have led to growing recognition of various mechanisms contributing to disease development in different patient groups. […] The clinical categories of ocular and generalized MG can be divided further based on autoantibody status, age, and thymic pathology. […] Much like other autoimmune conditions, a genetic predisposition contributes to development, with twin and family studies consistently demonstrating elevated prevalence rates of MG and other autoimmune disorders.
#3 What Causes Myasthenia Gravis | Pompa Program
https://pompaprogram.com/what-causes-myasthenia-gravis/
Viral infections like hepatitis C, Epstein-Barr virus herpes simplex virus, West Nile Virus, Influenza A, and COVID-19 are all linked with Myasthenia Gravis. […] Myasthenia Gravis can be caused by other autoimmune conditions. These include Autoimmune Thyroiditis, Systemic Lupus Erythematosus (SLE), Sjogrenâs Syndrome, and Rheumatoid Arthritis (RA). Each of these diseases causes the body to produce autoantibodies that attack its own healthy tissues. […] People with thyroid conditions, specifically hyperthyroidism (an overactive thyroid) are at an increased risk for developing myasthenia gravis. In patients with hyperthyroidism, the immune system is overactive and produces antibodies that attack the nerve cells in the neuromuscular junction. This can lead to muscle weakness and fatigue. In addition, some studies suggest that hyperthyroidism may increase the risk of developing myasthenia gravis.
#3 What Causes Myasthenia Gravis? Symptoms
https://www.emedicinehealth.com/what_causes_myasthenia_gravis/article_em.htm
Certain triggers may cause symptoms of myasthenia gravis to worsen, such as: Exposure to extreme heat, Emotional stress, Infection, Systemic illness, Pregnancy, The menstrual cycle. […] Certain drugs may precipitate or worsen myasthenia gravis symptoms, including: Antibiotics, Penicillamine, Beta-blockers, Lithium, Magnesium, Procainamide, Verapamil, Quinidine, Chloroquine, Prednisone, Timolol, Anticholinergics, Neuromuscular blocking agents, Nitrofurantoin, Cancer immunotherapy.
#3 Myasthenia Gravis and Pregnancy
https://www.nationwidechildrens.org/conditions/health-library/myasthenia-gravis-and-pregnancy
Myasthenia gravis is an autoimmune disorder. This means the body makes antibodies that attack its own tissues. People get myasthenia gravis when their bodys immune system attacks the connections of the nerves and muscle cells. It isn’t clear why people get autoimmune disorders. Its likely a mix of your genes, things in the environment, and allergies. […] Approximately 10% to 15% of babies born to women with myasthenia gravis may have the infant form of the disorder (neonatal myasthenia gravis). It happens when antibodies common in myasthenia gravis cross the placenta to the baby. These babies may be weak, with poor suck, and they may have breathing problems. This condition is often short-term (temporary), lasting only a few weeks.
#3
https://www.jci.org/articles/view/179742
Viral infection has been posited for decades to be a contributor to MG, with thus far limited support. […] Late-onset MG occurs in the context of immune system aging, which is associated with reduced ability to fight infections, reduced response to immunization, increased risk of cancer, and increased rates of autoimmunity. […] Approximately 10% of patients with MG, nearly all of whom have AChR antibodies, have a paraneoplastic form of the disease triggered by the thymoma. […] The development of immune checkpoint inhibitors (ICIs) has led to dramatic benefits for patients with treatment-resistant malignancy, but the unrestrained activation of the immune system has led to de novo induction or worsening of autoimmune disorders in at least 20% of patients depending on the agent and neoplasm.