Karłowatość – Patofizjologia i mechanizm

Karłowatość
Patofizjologia i mechanizm

Karłowatość definiowana jest jako wzrost dorosłego poniżej 147 cm i dzieli się na proporcjonalną (PSS) oraz nieproporcjonalną (DSS). Najczęstszą przyczyną są mutacje genetyczne, z achondroplazją stanowiącą około 70% przypadków, spowodowaną mutacją w genie FGFR3, prowadzącą do zahamowania endochondralnej ossyfikacji kości. Achondroplazja dziedziczona jest autosomalnie dominująco, a około 80% przypadków wynika z nowych mutacji ojcowskich, których częstość wzrasta z wiekiem ojca i ekspozycją na promieniowanie jonizujące. Inne genetyczne formy karłowatości obejmują dysplazję spondyloepifizarną, diastroficzną (mutacje w SLC26A2) oraz pierwotną, związaną z defektami w genach regulujących proliferację komórkową i cykl komórkowy (np. mutacje w CENPE). Niedobór hormonu wzrostu (GH) jest główną przyczyną karłowatości proporcjonalnej, a zespół Larona wynika z mutacji receptorów GH, prowadząc do wysokiego poziomu GH przy niskim efekcie biologicznym. Diagnostyka opiera się na ocenie klinicznej, badaniach hormonalnych (GH, IGF-1, IGFBP-3) oraz analizie genetycznej, a większość przypadków achondroplazji można wykryć prenatalnie za pomocą USG.

Patogeneza karłowatości

Genetyczne mechanizmy karłowatości
Zaburzenia hormonalne w karłowatości
Molekularne mechanizmy karłowatości pierwotnej
Zaburzenia ossyfikacji i chondrogenezy
Inne mechanizmy karłowatości

Współczesne badania i odkrycia

Czynniki wzrostu fibroblastów i karłowatość
Nowe geny i szlaki sygnałowe
Modyfikacje tRNA a karłowatość
Karłowatość w kontekście rolniczym i hodowlanym

Implikacje kliniczne i podejścia terapeutyczne

Diagnostyka karłowatości
Podejścia terapeutyczne
Prognoza i jakość życia

Podsumowanie mechanizmów patogenetycznych

Kolejne rozdziały

Patogeneza karłowatości

Karłowatość to stan charakteryzujący się znacznie niższym wzrostem, zwykle definiowanym jako wzrost dorosłego poniżej 147 cm (4 stopy 10 cali). Jest to złożone zaburzenie, które może wynikać z różnych mechanizmów patogenetycznych, wpływających na proces wzrostu organizmu. Karłowatość można podzielić na dwa główne typy: proporcjonalną (PSS – Proportionate Short Stature) oraz nieproporcjonalną (DSS – Disproportionate Short Stature), w zależności od wyglądu fizycznego pacjenta.¹²

Genetyczne mechanizmy karłowatości

Najczęstszą przyczyną karłowatości są zaburzenia genetyczne, które wpływają na rozwój kości i chrząstek. Istnieje ponad 300 różnych schorzeń powodujących karłowatość, a większość z nich ma podłoże genetyczne.³⁴

Achondroplazja, najbardziej powszechna forma karłowatości, odpowiada za około 70% przypadków i jest spowodowana mutacją w genie FGFR3 (receptor czynnika wzrostu fibroblastów 3).⁵ Mutacja ta powoduje nadmierną aktywność białka FGFR3, co prowadzi do zahamowania wzrostu kości. W kontekście achondroplazji, mutacja ta powoduje, że FGFR3 staje się konstytutywnie aktywny, hamując wzrost kości.⁶

Achondroplazja jest dziedziczona w sposób autosomalny dominujący, co oznacza, że jedna zmutowana kopia genu w każdej komórce jest wystarczająca, aby spowodować zaburzenie. Około 80% osób z achondroplazją rodzi się rodzicom o normalnym wzroście; przypadki te są spowodowane nowymi mutacjami w genie FGFR3.⁷

Badania wykazały, że nowe mutacje genowe w achondroplazji są dziedziczone wyłącznie od ojca i występują podczas spermatogenezy; uważa się, że plemniki niosące mutację w FGFR3 mają selektywną przewagę nad plemnikami z normalnym FGFR3. Częstość mutacji w plemnikach prowadzących do achondroplazji wzrasta proporcjonalnie do wieku ojca, a także proporcjonalnie do ekspozycji na promieniowanie jonizujące.⁸

Inne genetyczne formy karłowatości obejmują dysplazję spondyloepifizarną, dysplazję diastroficzną i karłowatość pierwotną. Na przykład, dysplazja diastroficzna jest wynikiem mutacji w genie SLC26A2, który odpowiada za rozwój chrząstki i kości.⁹¹⁰

Zaburzenia hormonalne w karłowatości

Niedobór hormonu wzrostu (GH) jest częstą przyczyną karłowatości proporcjonalnej, znanej również jako karłowatość przysadkowa. Oś podwzgórzowo-przysadkowa utrzymuje poziom hormonów wzrostu w organizmie, które następnie bezpośrednio lub pośrednio, poprzez insulinopodobny czynnik wzrostu 1 (IGF-1), stymulują wydłużanie kości oraz wzrost tkanek miękkich i chrząstek.¹¹

Karłowatość przysadkowa może być dziedziczna, ale może również być spowodowana guzami, infekcjami lub zawałem (śmiercią tkanki) przysadki. W wielu przypadkach inne funkcje endokrynologiczne i seksualne pozostają normalne.¹²

Niedobór hormonu wzrostu (GHD) to stan medyczny, w którym organizm produkuje niewystarczającą ilość hormonu wzrostu. Hormon wzrostu, zwany również somatotropiną, jest hormonem polipeptydowym, który stymuluje wzrost i reprodukcję komórek. Jeśli brakuje tego hormonu, może dojść do zahamowania lub nawet zatrzymania wzrostu.¹³

Zespół Larona to rzadka forma karłowatości spowodowana nieprawidłowymi receptorami hormonu wzrostu w wątrobie. Receptory te stają się nieprawidłowe z powodu mutacji genów kodujących receptory. Wydzielanie GH jest normalne lub wysokie, ale hormon nie może stymulować wzrostu z powodu nieprawidłowych receptorów.¹⁴

Molekularne mechanizmy karłowatości pierwotnej

Karłowatość pierwotna to grupa zaburzeń charakteryzujących się zahamowaniem wzrostu, które rozpoczyna się przed urodzeniem i trwa przez całe życie. Geny związane z karłowatością pierwotną wydają się być zaangażowane w nakładające się procesy regulujące proliferację komórkową.¹⁵

Najbardziej prawdopodobna hipoteza tłumacząca to zjawisko zakłada, że poprzez zmniejszenie wydajności progresji cyklu komórkowego, geny karłowatości pierwotnej działają tak, aby zmniejszyć całkowitą liczbę komórek wytwarzanych podczas rozwoju, prowadząc do zmniejszenia rozmiaru tkanek i organizmu.¹⁶

Karłowatość mikrocefalna osteodysplastyczna pierwotna typu II (MOPDII) wynika z mutacji w obu kopiach genu pericentryny u danej osoby, powodując, że obie kopie nie działają prawidłowo. MOPDII ma autosomalny recesywny wzorzec dziedziczenia, co oznacza, że informacja genetyczna od obojga rodziców jest niezbędna, aby dziecko miało MOPDII.¹⁷

Badania wykazały, że mutacje w genie CENPE definiują nowy mechanizm związany z kinetocho-centromere dla karłowatości pierwotnej mikrocefaicznej. Defekty w białkach centrosomu, białkach związanych z centrosomem i białkach związanych z wrzecionem podziałowym są najczęstszą przyczyną pierwotnej mikrocefaliif i zespołów karłowatości pierwotnej mikrocefaicznej u ludzi.¹⁸

Zaburzenia ossyfikacji i chondrogenezy

W achondroplazji głównym defektem jest nieprawidłowa ossyfikacja endochondralna. Ossyfikacja okostnowa i śródkostnowa jest normalna. Kości rurowe są krótkie i szerokie, odzwierciedlając normalny wzrost okostnej. Wyrośla grzebienia biodrowego (wzrost apofizyjny) są normalne, dając początek dużym, kwadratowym skrzydłom biodrowym. Wzrost chrząstki trójpromienistej (wzrost endochondralny) jest nieprawidłowy, dając początek poziomym dachom panewki. Tak więc wzorce defektów pomagają wyjaśnić wiele obserwowanych klinicznych i radiograficznych cech achondroplazji.¹⁹

W achondroplazji, endochondralny wzrost kości jest zahamowany w ponad 90% kości w organizmie podczas lat rozwojowych. Gdy wzrost kości jest zahamowany, w organizmie jest mniej miejsca dla narządów i nerwów. U niektórych osób z achondroplazją może to prowadzić do problemów rozwojowych i zdrowotnych, które mają trwały wpływ.²⁰

Liniowy wzrost osoby zależy od równowagi między proliferacją a starzeniem się komórek chrząstki w płytce wzrostowej. Wiele mechanizmów reguluje ten proces.²¹

Hormony, które promują chondrogenezę, to GH, IGF-1, androgeny, T3/T4 (hormony tarczycy), podczas gdy glukokortykoidy hamują chondrogenezę. Oś GH-IGF-1 jest tylko jednym z wielu szlaków regulacyjnych przyrostu wzrostu. Wiele szlaków auto- i parakrynnych jest badanych; mutacja tych szlaków może prowadzić do niskiego wzrostu lub wysokiego wzrostu.²²

Inne mechanizmy karłowatości

Poza głównymi mechanizmami genetycznymi i hormonalnymi, karłowatość może być również spowodowana innymi czynnikami:

Niedobór składników odżywczych: Ciężkie niedożywienie podczas dzieciństwa może zahamować wzrost i przyczynić się do niskiego wzrostu.²³
Choroby przewlekłe: Niektóre choroby przewlekłe, jeśli nie są odpowiednio leczone, mogą wpływać na wzrost i przyczyniać się do karłowatości.²⁴
Genetyczne mechanizmy receptorów GH: Mutacje w genach GHR mogą zakłócać zdolność GHR do interakcji z peptydem GH. Prawie 30 mutacji GHR zostało zgłoszonych jako związanych z zakłócaniem kombinacji GH-GHR.²⁵

Współczesne badania i odkrycia

Niedawne badania dotyczące karłowatości ujawniły nowe ścieżki i mechanizmy, które przyczyniają się do lepszego zrozumienia tej złożonej grupy schorzeń.

Czynniki wzrostu fibroblastów i karłowatość

Badania wykazały, że podwyższona sygnalizacja czynnika wzrostu fibroblastów (FGF) jest kluczowa dla patogenezy karłowatości kończyn. Podwyższenie sygnalizacji FGF, głównie z powodu zwiększonej ekspresji Fgf18 po inaktywacji Evc2 w ochrzęstnej, krytycznie przyczynia się do patogenezy karłowatości kończyn.²⁶

Badania na mysim modelu wykazały, że mutacja Evc2 prowadzi do karłowatości poprzez wpływ na proliferację i/lub dojrzewanie chondrocytów płytki wzrostowej, ale nie wpływa na zagęszczenie mezenchymalne lub różnicowanie zagęszczonych komórek mezenchymalnych w chondrocyty. W badaniach wykazano, że mutacja nonsensowna w Evc2, która naśladuje mutacje obserwowane u pacjentów EvC, prowadzi do upośledzonej, ale nie zniesionej sygnalizacji Hedgehog. Zatem zarówno zmniejszona sygnalizacja Hedgehog, jak i podwyższona sygnalizacja FGF odgrywają kluczową rolę w patogenezie unikalnej formy karłowatości, która charakteryzuje mutanty Evc2.²⁷

Nowe geny i szlaki sygnałowe

Odkryto, że delecja małego cytoplazmatycznego białka błonowego, Tmem263, powoduje poważne upośledzenie podłużnego wzrostu kości, a upośledzony wzrost kości był spowodowany zahamowaniem ekspresji i/lub poziomów białka receptora hormonu wzrostu w wątrobie.²⁸

Ustalono, że karłowatość była spowodowana znacznym zmniejszeniem ekspresji wątrobowej receptora hormonu wzrostu (GHR), niewielkim wzrostem poziomu GH w surowicy i zmniejszeniem poziomu IGF-I w surowicy, co skutkowało zakłóceniem osi regulacyjnej GH/IGF-I tworzenia kości endochondralnej.²⁹

Badania wykazały również, że dysfunkcja MITOL powoduje karłowatość z niedorozwojem przysadki przedniej. Myszy z niedoborem genu regulującego mitochondria Mitol wykazują zmniejszony wzrost w połączeniu z niedorozwojem przysadki przedniej i obniżonym poziomem hormonu wzrostu.³⁰

Modyfikacje tRNA a karłowatość

Nowe badania odkryły, że brak modyfikacji tRNA N7-metylguanozyny (m7G) u pacjentów powoduje rodzaj karłowatości pierwotnej, ale podstawowy mechanizm pozostawał nieznany. Badacze donoszą, że utrata m7G przeprogramowuje metabolizm komórkowy, prowadząc do patogenezy karłowatości pierwotnej.³¹

Mechanistycznie, knockout Mettl1 zmniejszał ilość tRNA zmodyfikowanych m7G i hamował translację mRNA związanych z cytoszkieletem i sygnalizacją Rho GTPazy. Ogólnie, badanie ujawnia kluczową rolę modyfikacji tRNA m7G w rozwoju kości poprzez regulację metabolizmu komórkowego i wskazuje na zawieszenie inicjacji translacji jako mechanizm kontroli jakości w odpowiedzi na dysregulację tRNA.³²

Karłowatość w kontekście rolniczym i hodowlanym

Badania nad karłowatością mają również zastosowanie w rolnictwie i hodowli. Mechanizm karłowacenia w podkładkach klonalnych jabłoni jest napędzany przez złożone interakcje między czynnikami anatomicznymi, hormonalnymi, genetycznymi i fenolowymi, oferując potencjał dla zaawansowanej manipulacji genetycznej w celu optymalizacji rozmiaru drzewa i zwiększenia produktywności sadu.³³

Podstawowe mechanizmy karłowacenia indukowanego przez podkładkę są wieloaspektowe i obejmują interakcje między czynnikami fenotypowymi, anatomicznymi, genetycznymi i fitohormonalnymi. Anatomicznie, podkładki karłowe wykazują wyższy stosunek kory do drewna i ograniczoną przewodność hydrauliczną, co przyczynia się do zmniejszonej energii podkładki.³⁴

Ponadto akumulacja związków fenolowych w połączeniu szczepienia podkładek karłowatych dodatkowo moduluje zahamowanie wzrostu. W badaniach wykazano, że PmLBD3 jest kluczowym czynnikiem transkrypcji, który reguluje równowagę hormonów poprzez szlaki sygnałowe auksyny i brassinolidów i powoduje karłowatość roślin w owocach pestkowych.³⁵

Implikacje kliniczne i podejścia terapeutyczne

Zrozumienie mechanizmów patogenetycznych karłowatości ma kluczowe znaczenie dla opracowania skutecznych strategii leczenia i poprawy jakości życia osób dotkniętych tymi schorzeniami.

Diagnostyka karłowatości

Diagnoza karłowatości wymaga kombinacji oceny klinicznej, testów hormonalnych i analizy genetycznej. Wykrycie poziomów GH i IGFBP-3, wraz z IGF-1, jest kluczowe dla wczesnej diagnozy i kompleksowej oceny.³⁶

Większość przypadków achondroplazji można zdiagnozować przed urodzeniem (poprzez zastosowanie USG w późniejszych stadiach ciąży). USG może pokazać krótsze niż przeciętnie ramiona i nogi, lub czy głowa dziecka jest większa niż przeciętna. Istnieją inne typy karłowatości, które można zdiagnozować jeszcze wcześniej w ciąży, i istnieją inne typy, które nie mogą być zdiagnozowane aż do urodzenia.³⁷

Podejścia terapeutyczne

Nie ma leku na karłowatość spowodowaną zaburzeniami genetycznymi. Zapobieganie i leczenie towarzyszących problemów zdrowotnych to jedyny kierunek działania dostępny w tym momencie dla małych ludzi i ich rodzin.³⁸

Leczenie karłowatości zwykle obejmuje:

Iniekcje hormonu wzrostu: W przypadku niedoboru hormonu wzrostu, iniekcje syntetycznego hormonu wzrostu mogą pomóc. Dzieci otrzymujące to leczenie nie zawsze osiągają przeciętny wzrost, ale mogą się do niego zbliżyć.³⁹
Zabiegi chirurgiczne: Mogą obejmować korekty kierunku wzrostu kości, stabilizację kręgosłupa, zwiększenie kanału w kręgach otaczających rdzeń kręgowy w celu odciążenia rdzenia kręgowego.⁴⁰
Leczenie objawów: Karłowatość, niezależnie od przyczyny, nie może być wyleczona ani skorygowana. Istnieją jednak pewne terapie, które mogą pomóc zmniejszyć ryzyko powikłań.⁴¹

W przypadku achondroplazji, ludzki hormon wzrostu nie ma zastosowania w jej leczeniu, ponieważ choroba nie jest spowodowana brakiem hormonu wzrostu. Leczenie koncentruje się na profilaktyce, zarządzaniu i leczeniu powikłań medycznych, a także na wsparciu społecznym i rodzinnym.⁴²

Obecnie prowadzone są wstępne badania nad lekiem zwanym vosoritide w leczeniu objawów achondroplazji, ale są one dopiero w początkowej fazie.⁴³

Prognoza i jakość życia

Prognoza dla każdego typu karłowatości jest różna. Karłowatość spowodowana tylko niedoborem hormonu wzrostu ma inną prognozę niż karłowatość spowodowana achondroplazją lub innymi dysplazjami szkieletowymi.⁴⁴

Większość osób z achondroplazją prowadzi pełne, produktywne życie. Większość zaburzeń, które powodują karłowatość, nie wpływa na zdolności intelektualne, oczekiwaną długość życia, ani zdolność do pracy i osiągania celów. Jednak niektóre formy karłowatości mogą skracać oczekiwaną długość życia ze względu na wynikające z nich problemy medyczne.⁴⁵

Dzieci z karłowatością przysadkową mają normalną inteligencję i przy wczesnym wykryciu i leczeniu, wiele z nich może również osiągnąć normalny wzrost.⁴⁶

Podsumowanie mechanizmów patogenetycznych

Karłowatość jest spowodowana różnymi mechanizmami patogenetycznymi, w tym mutacjami genetycznymi, zaburzeniami hormonalnymi i nieprawidłowym rozwojem kości i chrząstek. Główne mechanizmy obejmują:

Mutacje genetyczne wpływające na rozwój kości i chrząstek, takie jak mutacje w genie FGFR3 w achondroplazji.
Zaburzenia hormonalne, takie jak niedobór hormonu wzrostu, zaburzenie czynności przysadki lub nieprawidłowe receptory hormonów.
Zaburzenia ossyfikacji endochondralnej, które wpływają na wzrost długich kości.
Dysregulacja cyklu komórkowego, która wpływa na całkowitą liczbę komórek wytwarzanych podczas rozwoju.
Modyfikacje epigenetyczne, takie jak modyfikacje tRNA, które wpływają na translację białek.

Zrozumienie tych mechanizmów ma kluczowe znaczenie dla opracowania skutecznych strategii terapeutycznych i poprawy jakości życia osób dotkniętych karłowatością.⁴⁷⁴⁸⁴⁹

Kolejne rozdziały

Zapraszamy do dalszego czytania naszego leksykonu.

Wybierz kolejny rozdział z menu poniżej, aby otworzyć nową podstronę kompedium wiedzy i uzyskać szczegółowe informację o leku, substancji lub chorobie.

Materiały źródłowe

#1 Dwarfism – StatPearls – NCBI Bookshelf
https://www.ncbi.nlm.nih.gov/books/NBK563282/
Dwarfism is broadly categorized into two types based on the patient’s physical appearance, which are: proportionate short stature (PSS) and disproportionate short stature (DSS). […] The short stature can either be due to an underlying medical condition or a standard variant of growth. FSS, CDGP, and ISS described below can be considered as normal variants of growth, while the rest are pathological causes- […] Growth hormone deficiency is a frequent cause of dwarfism. The hypothalamic-pituitary axis maintains the levels of growth hormones in the body, which then directly or indirectly, through Insulin-like growth factor-1 (IGF-1), stimulates bone elongation, and growth of soft tissue and cartilage. […] The linear growth of an individual depends on the equilibrium between proliferation and senescence of cartilage cells at the growth plate. Multiple mechanisms regulate this process-
#2 Dwarfism – Wikipedia
https://en.wikipedia.org/wiki/Dwarfism
Dwarfism can result from many medical conditions, each with its own separate symptoms and causes. Extreme shortness in humans with proportional body parts usually has a hormonal cause, such as growth hormone deficiency, once called pituitary dwarfism. Achondroplasia is responsible for the majority of human dwarfism cases, followed by spondyloepiphyseal dysplasia and diastrophic dysplasia. […] The most recognizable and most common form of dwarfism in humans is achondroplasia, which accounts for 70% of dwarfism cases, and occurs in 4 to 15 out of 100,000 live births. […] Achondroplasia is an autosomal dominant disorder caused by the presence of an altered allele in the genome. If a pair of achondroplasia alleles are present, the result is fatal, usually perinatally. Achondroplasia is a mutation in the fibroblast growth factor receptor 3. In the context of achondroplasia, this mutation causes FGFR3 to become constitutively active, inhibiting bone growth.
#3 Understanding Dwarfism: An In-Depth Exploration of a Unique Condi
https://www.openaccessjournals.com/articles/understanding-dwarfism-an-indepth-exploration-of-a-unique-condition-17354.html
Dwarfism is commonly defined as a medical or genetic condition resulting in a significantly shorter stature compared to the average height of the general population. The average height considered indicative of dwarfism is four feet ten inches (147 centimeters) or shorter. […] Understanding the causes of dwarfism is crucial for both medical professionals and the general public. Dwarfism can result from a variety of factors, including genetic mutations, hormonal imbalances and medical conditions affecting bone and cartilage development. […] The majority of dwarfism cases are attributed to genetic factors. One of the most prevalent genetic causes is achondroplasia, a condition that affects the development of cartilage and bone, leading to shorter limbs and stature. […] Achondroplasia, the most prevalent genetic cause of dwarfism, occurs due to a mutation in the FGFR3 gene, affecting bone growth.
#4 Dwarfism: Types, Causes, and More
https://www.healthline.com/health/dwarfism
Researchers believe there are more than 300 conditions that cause dwarfism. Most causes are genetic. The most common causes include: […] Though achondroplasia is a genetic condition, four out of five people who have it also have two parents who are average sized. If you have achondroplasia, you have one mutated gene associated with the condition and one unaffected version of that gene. This is the most common cause of dwarfism. […] Dwarfism is usually the result of a genetic mutation. But having a gene or genes responsible for dwarfism can occur in a couple of ways. […] In some cases, it can happen spontaneously. You may not be born with mutated genes inherited from a parent. Instead, a mutation of your genes happens on its own usually without a cause doctors can discover. […] Other risk factors for dwarfism include a hormone deficiency or malnutrition. There usually arent any risk factors for a hormone deficiency, but it can often be successfully treated. Serious malnutrition, which leads to weak bones and muscles, can also be overcome in many cases with a healthy, more nutrient-rich diet.
#5 Dwarfism – Wikipedia
https://en.wikipedia.org/wiki/Dwarfism
Dwarfism can result from many medical conditions, each with its own separate symptoms and causes. Extreme shortness in humans with proportional body parts usually has a hormonal cause, such as growth hormone deficiency, once called pituitary dwarfism. Achondroplasia is responsible for the majority of human dwarfism cases, followed by spondyloepiphyseal dysplasia and diastrophic dysplasia. […] The most recognizable and most common form of dwarfism in humans is achondroplasia, which accounts for 70% of dwarfism cases, and occurs in 4 to 15 out of 100,000 live births. […] Achondroplasia is an autosomal dominant disorder caused by the presence of an altered allele in the genome. If a pair of achondroplasia alleles are present, the result is fatal, usually perinatally. Achondroplasia is a mutation in the fibroblast growth factor receptor 3. In the context of achondroplasia, this mutation causes FGFR3 to become constitutively active, inhibiting bone growth.
#6 Achondroplasia – Wikipedia
https://en.wikipedia.org/wiki/Achondroplasia
Achondroplasia is caused by a mutation in the fibroblast growth factor receptor 3 (FGFR3) gene that results in its protein being overactive. Achondroplasia results in impaired endochondral bone growth (bone growth within cartilage). The disorder has an autosomal dominant mode of inheritance, meaning only one mutated copy of the gene is required for the condition to occur. […] When the FGFR3 gene is mutated it interferes with how this protein interacts with growth factors leading to complications with bone production. Cartilage is not able to fully develop into bone, causing the individual to be disproportionately shorter in height. […] In achondroplasia, the mutated form of the receptor is constitutively active, and this leads to severely shortened bones. This is an example of a gain of function mutation. The effect is genetically dominant, with one variant of the FGFR3 gene being sufficient to cause achondroplasia, while two copies of the mutant gene are invariably fatal (recessive lethal) before or shortly after birth. This occurs due to respiratory failure from an underdeveloped ribcage.
#7 Achondroplasia: MedlinePlus GeneticsLock
https://medlineplus.gov/genetics/condition/achondroplasia/
Achondroplasia is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. About 80 percent of people with achondroplasia are born to parents who do not have the condition and are of average heights; these cases are caused by new variants in the FGFR3 gene. In the remaining cases, people with achondroplasia inherit an altered FGFR3 gene from one or two affected parents. Individuals who inherit two altered copies of the FGFR3 gene typically have a severe form of achondroplasia that causes extreme shortening of the bones and an underdeveloped rib cage. These individuals are usually stillborn or die shortly after birth from respiratory failure.
#8 Achondroplasia – Wikipedia
https://en.wikipedia.org/wiki/Achondroplasia
Studies have demonstrated that new gene mutations for achondroplasia are exclusively inherited from the father and occur during spermatogenesis; it has been theorized that sperm carrying the mutation in FGFR3 have a selective advantage over sperm with normal FGFR3. The frequency of mutations in sperm leading to achondroplasia increases in proportion to paternal age, as well as in proportion to exposure to ionizing radiation.
#9 Dwarfism: Types, causes, and information
https://www.medicalnewstoday.com/articles/320286
Dwarfism has many different causes. Several of the causes of dwarfism can lead to other health problems, such as osteoarthritis. […] Some conditions that cause dwarfism disrupt the hormones that enable the body to grow. Dwarfism can also be due to metabolic disorders or malnourishment. […] A group of conditions called skeletal dysplasias is the most common cause of dwarfism. […] Skeletal dysplasias cause the bones to grow abnormally, resulting in a small stature. This abnormal growth can also result in uneven growth that produces a body of unusual proportions. […] Typically, skeletal dysplasias are genetic conditions. Most people with skeletal dysplasias have parents of normal stature. […] The three most common types of skeletal dysplasias are achondroplasia, spondyloepiphyseal dysplasia congenita, and diastrophic dysplasia.
#10 Dwarfism and genetics | EBSCO Research Starters
https://www.ebsco.com/research-starters/health-and-medicine/dwarfism-and-genetics
Skeletal dysplasias are the most common causes of dwarfism and are the major cause of disproportionate types of dwarfism. More than five hundred skeletal dysplasias have been identified. […] Diastrophic dysplasia is an inherited autosomal recessive condition linked to the SLC26A2 gene, which is responsible for cartilage and bone formation. […] Growth hormone deficiencies arise from mutations to the GH1, GHRHR, or BTK genes, which control growth hormone production and reception and antibody production, respectively. […] Turner syndrome is characterized by the absence of or damage to one of the X chromosomes in most of the cells in the body. Short stature and the failure to develop sexually are hallmarks of Turner syndrome. […] Genetic testing is 99-percent sensitive and available in clinical laboratories. The continues to investigate genetic links to dwarfism. […] Some forms of dwarfism can be treated through state-of-the-art surgical and medical interventions such as bone-lengthening procedures, reconstructive surgery, and growth and sex hormone replacement.
#11 Dwarfism – StatPearls – NCBI Bookshelf
https://www.ncbi.nlm.nih.gov/books/NBK563282/
Dwarfism is broadly categorized into two types based on the patient’s physical appearance, which are: proportionate short stature (PSS) and disproportionate short stature (DSS). […] The short stature can either be due to an underlying medical condition or a standard variant of growth. FSS, CDGP, and ISS described below can be considered as normal variants of growth, while the rest are pathological causes- […] Growth hormone deficiency is a frequent cause of dwarfism. The hypothalamic-pituitary axis maintains the levels of growth hormones in the body, which then directly or indirectly, through Insulin-like growth factor-1 (IGF-1), stimulates bone elongation, and growth of soft tissue and cartilage. […] The linear growth of an individual depends on the equilibrium between proliferation and senescence of cartilage cells at the growth plate. Multiple mechanisms regulate this process-
#12 Pituitary dwarfism | pathology | Britannica
https://www.britannica.com/science/pituitary-dwarfism
Pituitary dwarfism, caused by a deficiency of pituitary growth hormone, is the chief endocrine form of dwarfism and may be hereditary; tumours, infections, or infarction (tissue death) of the pituitary can also induce dwarfism. […] In many cases, other endocrine and sexual functions remain normal.
#13 Dwarfism – Wikipedia
https://en.wikipedia.org/wiki/Dwarfism
Growth hormone deficiency (GHD) is a medical condition in which the body produces insufficient growth hormone. Growth hormone, also called somatotropin, is a polypeptide hormone which stimulates growth and cell reproduction. If this hormone is lacking, stunted or even halted growth may become apparent.
#14 Dwarfism | PPT
https://www.slideshare.net/slideshow/dwarfism-76761121/76761121
Laron dwarfism occurs due to the presence of abnormal growth hormone secretagogue (GHS) receptors in liver. GHS receptors become abnormal because of the mutation of genes for the receptors. GH secretion is normal or high. But the hormone cannot stimulate growth because of the abnormal GHS receptors. […] Most types of dwarfism are known as Skeletal Dysplasias-conditions of abnormal bone growth. They’re divided into two types: I. Short-Trunk: -Those have a shortened trunk with more average-sized limbs II. Short-Limb: -Those have an average-sized trunk but shortened arms and legs. […] This genetic condition results in short stature, with adult height usually varying from slightly under 3ft to slightly 4 ft. Other characteristics can include clubfeet, a cleft palate, and a barrel-chested appearance. SED occurs approximately once in every 100,000 births.
#15 Mechanisms and pathways of growth failure in primordial dwarfism
https://pmc.ncbi.nlm.nih.gov/articles/PMC3197200/
Although on one level mammalian body size can be reduced to the simple problem of controlling cell numbers output during development, the determination of body size is in fact the complex integration of many factors. […] Organism development requires high-fidelity regulatory networks to control and coordinate patterning and growth. […] A common theme for these pathways is their integration of multiple inputs and subsequent action on a range of overlapping downstream effectors that modulate growth through cell mass, cell survival, and/or cellular proliferation. […] In contrast, rather than acting in these signaling pathways, primordial dwarfism genes encode downstream cell proliferation/cell survival proteins. […] The identified primordial dwarfism genes appear to be involved in overlapping processes regulating cellular proliferation.
#16 Mechanisms and pathways of growth failure in primordial dwarfism
https://pmc.ncbi.nlm.nih.gov/articles/PMC3197200/
Overall, the most plausible unifying hypothesis is that by reducing the efficiency of cell cycle progression, primordial dwarfism genes act to reduce the total cell number generated during development, leading to reduced tissue and organism size. […] As a whole, the primordial dwarfism genes are involved in cell cycle progression, with organism size most likely reduced in these conditions through reduced cell number.
#17 Primordial Dwarfism Causes & Symptoms
https://www.nemours.org/conditions-treatments/primordial-dwarfism/about-primordial-dwarfism.html
MOPDII results when there is a gene change (mutation) in each copy of an individuals pericentrin gene, causing both copies to not work as they usually do. […] MOPDII has an autosomal recessive inheritance pattern. This means that the genetic information from both parents is necessary for the child to have MOPDII, and there would be a 25% recurrence chance in future pregnancies. […] There is genetic testing clinically available to confirm this diagnosis. MOPDII is associated with changes in a gene called pericentrin (PCNT). […] A majority of individuals with MOPDII will develop moyamoya, brain aneurysms, or both. Moyamoya is diagnosed at a younger age than aneurysms, as early as the neonatal period. Aneurysm risk continues throughout the lifespan. […] Insulin resistance is associated with MOPDII and can progress to frank diabetes, often in the teens.
#18 Mutations in CENPE define a novel kinetochore-centromeric mechanism for microcephalic primordial dwarfism
https://escholarship.org/uc/item/4f32r041
Defects in centrosome, centrosomal-associated and spindle-associated proteins are the most frequent cause of primary microcephaly (PM) and microcephalic primordial dwarfism (MPD) syndromes in humans. […] This suggests that impaired mitotic entry, progression and exit strongly contribute to PM and MPD. […] Here, we described novel compound heterozygous variants in CENPE in two siblings who exhibit a profound MPD associated with developmental delay, simplified gyri and other isolated abnormalities. […] Our cellular analysis shows that a pathogenic defect in CENP-E, a kinetochore-core protein, largely phenocopies PCNT-mutated microcephalic osteodysplastic primordial dwarfism-type II patient cells. […] These results highlight a common underlying pathomechanism. […] Our findings provide the first evidence for a kinetochore-based route to MPD in humans.
#19 Achondroplasia: Practice Essentials, Anatomy, Pathophysiology
https://emedicine.medscape.com/article/1258401-overview
Dwarfing conditions are frequently referred to as short-limb or short-trunk types, according to whether the trunk or limbs are more extensively involved. Achondroplasia, hypochondroplasia, and metaphyseal chondrodysplasias are considered short-limb dwarfing conditions. These patients’ sitting height is within normal range. […] The primary defect found in patients with achondroplasia is abnormal endochondral ossification. Periosteal and intramembranous ossification is normal. Tubular bones are short and broad, reflecting normal periosteal growth. The iliac crest apophyses (appositional growth) are normal, giving rise to large, square iliac wings. The growth of the triradiate cartilage (endochondral growth) is abnormal, giving rise to horizontal acetabular roofs. Thus, the patterns of defects help to explain many of the observed clinical and radiographic characteristics of achondroplasia.
#20 Achondroplasia Health Impact and Care
https://achondroplasia.biomarin.com/en-us/what-is-achondroplasia/
Bones play an important role in mobility, daily functioning, and overall health. In achondroplasia, bone growth is slowed or inhibited. […] In achondroplasia, endochondral bone growth is inhibited in over 90% of bones in the body during developmental years. […] When bone growth is inhibited, there’s less space inside the body for organs and nerves. For some people with achondroplasia, this can lead to developmental and health issues that have a lasting impact. […] Inhibited bone growth can affect health in different ways.
#21 Dwarfism – StatPearls – NCBI Bookshelf
https://www.ncbi.nlm.nih.gov/books/NBK563282/
Dwarfism is broadly categorized into two types based on the patient’s physical appearance, which are: proportionate short stature (PSS) and disproportionate short stature (DSS). […] The short stature can either be due to an underlying medical condition or a standard variant of growth. FSS, CDGP, and ISS described below can be considered as normal variants of growth, while the rest are pathological causes- […] Growth hormone deficiency is a frequent cause of dwarfism. The hypothalamic-pituitary axis maintains the levels of growth hormones in the body, which then directly or indirectly, through Insulin-like growth factor-1 (IGF-1), stimulates bone elongation, and growth of soft tissue and cartilage. […] The linear growth of an individual depends on the equilibrium between proliferation and senescence of cartilage cells at the growth plate. Multiple mechanisms regulate this process-
#22 Dwarfism – StatPearls – NCBI Bookshelf
https://www.ncbi.nlm.nih.gov/books/NBK563282/
The hormones which promote chondrogenesis are GH, IGF-1, androgens, T3/T4 (thyroid hormones), while glucocorticoids inhibit chondrogenesis. […] GH-IGF-1 axis is only one of the many regulatory pathways of height gain. Many autocrine and paracrine pathways are under research; mutation of these can lead to short stature or tall stature. […] SHOX gene codes for transcription factors that regulate the activity of other genes and its mutation is associated with a spectrum of clinical manifestations with Leri-Weill dyschondrosteosis (LWD) on the critical end, and nonspecific short stature on the other.
#23 Understanding Dwarfism: An In-Depth Exploration of a Unique Condi
https://www.openaccessjournals.com/articles/understanding-dwarfism-an-indepth-exploration-of-a-unique-condition-17354.html
Skeletal dysplasias are a group of genetic disorders affecting bone and cartilage development. […] Severe malnutrition during childhood can stunt growth and contribute to short stature. […] Certain chronic illnesses, if not properly managed, can affect growth and contribute to dwarfism. […] Living with dwarfism can present various medical challenges and individuals affected by this condition often require specialized medical care throughout their lives. Understanding these implications is crucial for providing appropriate support and treatment. […] Orthopedic problems are common in individuals with dwarfism due to the abnormal development of bones and joints. […] Some forms of dwarfism, particularly those associated with disproportionate growth, can lead to respiratory complications. […] Certain types of dwarfism, such as osteogenesis imperfecta, can be associated with hearing problems. […] Dental issues, including crowded or misaligned teeth, are common in individuals with certain forms of dwarfism.
#24 Understanding Dwarfism: An In-Depth Exploration of a Unique Condi
https://www.openaccessjournals.com/articles/understanding-dwarfism-an-indepth-exploration-of-a-unique-condition-17354.html
Skeletal dysplasias are a group of genetic disorders affecting bone and cartilage development. […] Severe malnutrition during childhood can stunt growth and contribute to short stature. […] Certain chronic illnesses, if not properly managed, can affect growth and contribute to dwarfism. […] Living with dwarfism can present various medical challenges and individuals affected by this condition often require specialized medical care throughout their lives. Understanding these implications is crucial for providing appropriate support and treatment. […] Orthopedic problems are common in individuals with dwarfism due to the abnormal development of bones and joints. […] Some forms of dwarfism, particularly those associated with disproportionate growth, can lead to respiratory complications. […] Certain types of dwarfism, such as osteogenesis imperfecta, can be associated with hearing problems. […] Dental issues, including crowded or misaligned teeth, are common in individuals with certain forms of dwarfism.
#25 Growth Hormone Receptor Mutations Related to Individual Dwarfism
https://www.mdpi.com/1422-0067/19/5/1433
Mutations in the GHR gene can alter the ability of GHR to interact with the GH peptide. Nearly 30 GHR mutations have been reported to be associated with disturbing the GHâGHR combination. For example, a homozygous substitution mutation E42K was predicted to impair the binding affinity of GHR to GH in humans, and to be responsible for low serum levels of IGF-1, IGF binding protein (IGFBP)-3, and GH binding protein (GHBP). A nonsense mutation in the fourth exon of GHR (R43X) determines a premature termination in the protein translation process. As a result of the absence of the extracellular portion of the GHR, this patient had undetectable GHBP. GHR C94S was found to lose its ability to bind to GH. A 307 G > A substitution in exon 5 of GHR resulted in the replacement of the amino acid aspartic acid at position 103 with a residue of asparagine (D103N). This substitution involved the highly conserved aspartic acid 103, which could be responsible for damaging GHR functionality.
#26 Elevated Fibroblast Growth Factor Signaling Is Critical for the Pathogenesis of the Dwarfism in Evc2/Limbin Mutant Mice | PLOS Genetics
https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1006510
Elevated Fibroblast Growth Factor (FGF) signaling is critical for the pathogenesis of limb dwarfism. […] Elevation of FGF signaling, mainly due to increased Fgf18 expression upon inactivation of Evc2 in the perichondrium, critically contributes to the pathogenesis of limb dwarfism. […] Our data demonstrated that mutation in Evc2 only moderately affected Hedgehog-PTHrP feedback loop in the growth plate, which only partially contributes to the dwarfism. […] The mutation of Evc2 leads to dwarfism by affecting growth plate chondrocyte proliferation and/or maturation, but not by affecting mesenchymal condensation or differentiation of condensed mesenchymal cells into chondrocytes. […] We demonstrate that a nonsense mutation in Evc2 that mimics mutations seen in EvC patients leads to compromised but not abrogated Hedgehog signaling. […] We conclude that both reduced Hedgehog signaling and elevated FGF signaling play a critical role in the pathogenesis of the unique form of dwarfism that characterizes Evc2 mutants. […] Elevated FGF signaling plays critical role in the pathogenesis of dwarfism in Evc2 mutants.
#27 Elevated Fibroblast Growth Factor Signaling Is Critical for the Pathogenesis of the Dwarfism in Evc2/Limbin Mutant Mice | PLOS Genetics
https://journals.plos.org/plosgenetics/article?id=10.1371/journal.pgen.1006510
Elevated Fibroblast Growth Factor (FGF) signaling is critical for the pathogenesis of limb dwarfism. […] Elevation of FGF signaling, mainly due to increased Fgf18 expression upon inactivation of Evc2 in the perichondrium, critically contributes to the pathogenesis of limb dwarfism. […] Our data demonstrated that mutation in Evc2 only moderately affected Hedgehog-PTHrP feedback loop in the growth plate, which only partially contributes to the dwarfism. […] The mutation of Evc2 leads to dwarfism by affecting growth plate chondrocyte proliferation and/or maturation, but not by affecting mesenchymal condensation or differentiation of condensed mesenchymal cells into chondrocytes. […] We demonstrate that a nonsense mutation in Evc2 that mimics mutations seen in EvC patients leads to compromised but not abrogated Hedgehog signaling. […] We conclude that both reduced Hedgehog signaling and elevated FGF signaling play a critical role in the pathogenesis of the unique form of dwarfism that characterizes Evc2 mutants. […] Elevated FGF signaling plays critical role in the pathogenesis of dwarfism in Evc2 mutants.
#28 Tmem263 deletion disrupts the GH/IGF-1 axis and causes dwarfism and impairs skeletal acquisition
https://elifesciences.org/reviewed-preprints/90949/reviews
The study demonstrates that deletion of a small cytoplasmic membrane protein, Tmem263, caused severe impairment of longitudinal bone growth and that the impaired bone growth was caused by suppression of expression and/or protein levels of growth hormone receptor in the liver. […] It is determined that the dwarfism was caused by a substantial reduction in liver expression of growth hormone receptor (GHR), a slight increase in serum GH, and a reduction in serum IGF-I, which resulted in disruptive of GH/IGF-I regulatory axis of endochondral bone formation. […] The finding that TMEM263 is essential for normal hepatic GHR/IGF1 signaling is an important, and unexpected finding, one that is likely to stimulate further research into the underlying mechanisms of TMEM263 action, including the distinct possibility that these effects involve direct protein-protein interactions between GHR and TMEM263 on the plasma membrane of hepatocytes. […] However, there is insufficient evidence to definitively conclude that the observed alteration of hepatic GH/IGF1 signaling is causative of the body growth and skeletal phenotypes.
#29 Tmem263 deletion disrupts the GH/IGF-1 axis and causes dwarfism and impairs skeletal acquisition
https://elifesciences.org/reviewed-preprints/90949/reviews
The study demonstrates that deletion of a small cytoplasmic membrane protein, Tmem263, caused severe impairment of longitudinal bone growth and that the impaired bone growth was caused by suppression of expression and/or protein levels of growth hormone receptor in the liver. […] It is determined that the dwarfism was caused by a substantial reduction in liver expression of growth hormone receptor (GHR), a slight increase in serum GH, and a reduction in serum IGF-I, which resulted in disruptive of GH/IGF-I regulatory axis of endochondral bone formation. […] The finding that TMEM263 is essential for normal hepatic GHR/IGF1 signaling is an important, and unexpected finding, one that is likely to stimulate further research into the underlying mechanisms of TMEM263 action, including the distinct possibility that these effects involve direct protein-protein interactions between GHR and TMEM263 on the plasma membrane of hepatocytes. […] However, there is insufficient evidence to definitively conclude that the observed alteration of hepatic GH/IGF1 signaling is causative of the body growth and skeletal phenotypes.
#30 1.10. MITOL dysfunction causes dwarfism with anterior pituitary hypoplasia | ESPEYB18 | Yearbook of Paediatric Endocrinology 2021 | ESPE Yearbook of Paediatric Endocrinology
https://www.espeyearbook.org/ey/0018/ey0018.1-10
MITOL dysfunction causes dwarfism with anterior pituitary hypoplasia. […] This study shows that mice mitochondrial regulatory gene Mitol-deficient mice display reduced growth in combination with anterior pituitary hypoplasia and reduced growth hormone levels. […] MITOL encodes a ubiquitin ligase. Ablation of Mitol in nestin-expressing cells led to reduced expression of Gh, Prl, Ghrhr, and Pit1, suggesting dysregulation of pituitary transcription factor Pit1 by a yet unidentified mechanism. […] Many patients with mitochondrial diseases present with growth failure. These findings suggest that mitochondrial dysfunction may possibly underlie cases with unexplained hypopituitarism.
#31
https://www.jci.org/articles/view/177220/sd/2
Translation of mRNA to protein is tightly regulated by transfer RNAs (tRNAs), which are subject to various chemical modifications that maintain structure, stability, and function. Deficiency of tRNA N7-methylguanosine (m7G) modification in patients causes a type of primordial dwarfism, but the underlying mechanism remains unknown. Here we report that the loss of m7G rewires cellular metabolism, leading to the pathogenesis of primordial dwarfism. […] Mechanistically, Mettl1 knockout decreased abundance of m7G-modified tRNAs and inhibited translation of mRNAs relating to cytoskeleton and Rho GTPase signaling. […] Overall, our study unveils a critical role of m7G tRNA modification in bone development by regulation of cellular metabolism and indicates suspension of translation initiation as a quality control mechanism in response to tRNA dysregulation.
#32
https://www.jci.org/articles/view/177220/sd/2
Translation of mRNA to protein is tightly regulated by transfer RNAs (tRNAs), which are subject to various chemical modifications that maintain structure, stability, and function. Deficiency of tRNA N7-methylguanosine (m7G) modification in patients causes a type of primordial dwarfism, but the underlying mechanism remains unknown. Here we report that the loss of m7G rewires cellular metabolism, leading to the pathogenesis of primordial dwarfism. […] Mechanistically, Mettl1 knockout decreased abundance of m7G-modified tRNAs and inhibited translation of mRNAs relating to cytoskeleton and Rho GTPase signaling. […] Overall, our study unveils a critical role of m7G tRNA modification in bone development by regulation of cellular metabolism and indicates suspension of translation initiation as a quality control mechanism in response to tRNA dysregulation.
#33
https://link.springer.com/article/10.1007/s00425-024-04561-5
The dwarfing mechanism in apple clonal rootstocks is driven by complex interactions between anatomical, hormonal, genetic, and phenolic factors, offering potential for advanced genetic manipulation to optimize tree size and enhance orchard productivity. […] The underlying mechanisms of rootstock-induced dwarfism are multifaceted and involve interactions between phenotypic, anatomical, genetic, and phytohormonal factors. […] This review consolidates current understanding, highlighting the importance of auxin (IAA), cytokinins (CKs), gibberellins (GAs), and abscisic acid (ABA) in mediating growth suppression through impaired transport and hormone signaling. […] Anatomically, dwarf rootstocks exhibit a higher bark-to-wood ratio and restricted hydraulic conductivity, which contribute to reduced scion vigour.
#34
https://link.springer.com/article/10.1007/s00425-024-04561-5
The dwarfing mechanism in apple clonal rootstocks is driven by complex interactions between anatomical, hormonal, genetic, and phenolic factors, offering potential for advanced genetic manipulation to optimize tree size and enhance orchard productivity. […] The underlying mechanisms of rootstock-induced dwarfism are multifaceted and involve interactions between phenotypic, anatomical, genetic, and phytohormonal factors. […] This review consolidates current understanding, highlighting the importance of auxin (IAA), cytokinins (CKs), gibberellins (GAs), and abscisic acid (ABA) in mediating growth suppression through impaired transport and hormone signaling. […] Anatomically, dwarf rootstocks exhibit a higher bark-to-wood ratio and restricted hydraulic conductivity, which contribute to reduced scion vigour.
#35 PmLBD3 links auxin and brassinosteroid signalling pathways on dwarfism in Prunus mume | BMC Biology | Full Text
https://bmcbiol.biomedcentral.com/articles/10.1186/s12915-024-01985-z
Auxin signalling and brassinolide levels are linked by PmLBD3. […] Our findings showed that PmLBD3 is a key transcription factor that regulates the balance of hormones through the auxin and brassinolide signalling pathways and causes dwarf plants in stone fruits. […] The height of plants is a significant characteristic of fruit tree cultivation, and the cultivation of dwarf crops is generally associated with more condensed plant structures, as well as increased yield and improved quality. […] The phenomenon of plant dwarfing, which occurs as a result of material flow and hormonal interactions between the rootstock and scion following grafting, has consistently been a subject of concern and a significant approach in the breeding of dwarf crops and the selection of varieties. […] However, the precise molecular mechanism by which mume rootstocks exert control over plant dwarfing remains elusive and requires further investigation.
#36 What Is Dwarfism? – Consensus: AI Search Engine for Research
https://consensus.app/home/blog/what-is-dwarfism/
Diagnosing dwarfism involves a combination of clinical evaluation, hormonal testing, and genetic analysis. The detection of GH and IGFBP-3 levels, along with IGF-1, is crucial for early diagnosis and comprehensive evaluation. […] Dwarfism is a complex condition with various causes, including hormonal deficiencies and nutritional inadequacies. Understanding the underlying factors is essential for accurate diagnosis and effective treatment. Hormonal assessments and nutritional evaluations play a critical role in managing the condition and improving growth outcomes in affected individuals.
#37 Dwarfism | PPT
https://www.slideshare.net/slideshow/dwarfism-76761121/76761121
Most cases of achondroplasia can be diagnosed before birth (through the use of an ultrasound in the later stages of pregnancy). Ultrasounds can show shorter than average arms and legs, or whether the baby’s head is larger than average. There are other types of dwarfism that can be diagnosed even earlier in pregnancy and there are other types that can’t be diagnosed until after birth. There is no cure available for dwarfism caused by genetic disorders. Prevention and treatment of accompanying health concerns are the only course of action available at this time for little people and their families. […] Dwarfisms treatments don’t increase stature but may alleviate problems caused by complications. Surgical procedures that may correct problems with bones in people with disproportionate dwarfism. Some people with dwarfism elect to undergo limb-lengthening surgery. Growth hormone deficiency is treated with injections of a synthetic version of the hormone.
#38 Dwarfism | PPT
https://www.slideshare.net/slideshow/dwarfism-76761121/76761121
Most cases of achondroplasia can be diagnosed before birth (through the use of an ultrasound in the later stages of pregnancy). Ultrasounds can show shorter than average arms and legs, or whether the baby’s head is larger than average. There are other types of dwarfism that can be diagnosed even earlier in pregnancy and there are other types that can’t be diagnosed until after birth. There is no cure available for dwarfism caused by genetic disorders. Prevention and treatment of accompanying health concerns are the only course of action available at this time for little people and their families. […] Dwarfisms treatments don’t increase stature but may alleviate problems caused by complications. Surgical procedures that may correct problems with bones in people with disproportionate dwarfism. Some people with dwarfism elect to undergo limb-lengthening surgery. Growth hormone deficiency is treated with injections of a synthetic version of the hormone.
#39 Dwarfism: Types, Causes, and More
https://www.healthline.com/health/dwarfism
For people with growth hormone deficiency, injections of synthetic human growth hormone may be helpful. Children receiving this treatment dont always reach an average height, but they can get close. […] Surgical treatments include those that can help: correct the direction of bone growth, stabilize the spine, increase the channel in the vertebrae surrounding the spinal cord to relieve pressure on the spinal cord. […] Dwarfism, regardless of the cause, cant be cured or corrected. However, there are certain therapies that may help reduce the risk of complications.
#40 Dwarfism: Types, Causes, and More
https://www.healthline.com/health/dwarfism
For people with growth hormone deficiency, injections of synthetic human growth hormone may be helpful. Children receiving this treatment dont always reach an average height, but they can get close. […] Surgical treatments include those that can help: correct the direction of bone growth, stabilize the spine, increase the channel in the vertebrae surrounding the spinal cord to relieve pressure on the spinal cord. […] Dwarfism, regardless of the cause, cant be cured or corrected. However, there are certain therapies that may help reduce the risk of complications.
#41 Dwarfism: Types, Causes, and More
https://www.healthline.com/health/dwarfism
For people with growth hormone deficiency, injections of synthetic human growth hormone may be helpful. Children receiving this treatment dont always reach an average height, but they can get close. […] Surgical treatments include those that can help: correct the direction of bone growth, stabilize the spine, increase the channel in the vertebrae surrounding the spinal cord to relieve pressure on the spinal cord. […] Dwarfism, regardless of the cause, cant be cured or corrected. However, there are certain therapies that may help reduce the risk of complications.
#42 Dwarfism | Better Health Channel
https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/dwarfism
There is no cure for achondroplasia. Human growth hormone has no place in its management, as the condition is not caused by a lack of growth hormone. Treatment focuses on the prevention, management and treatment of medical complications as well as social and family support. […] There are currently preliminary trials on a medication called vosoritide to treat the symptoms of achondroplasia, but these are only in the initial stages.
#43 Dwarfism | Better Health Channel
https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/dwarfism
There is no cure for achondroplasia. Human growth hormone has no place in its management, as the condition is not caused by a lack of growth hormone. Treatment focuses on the prevention, management and treatment of medical complications as well as social and family support. […] There are currently preliminary trials on a medication called vosoritide to treat the symptoms of achondroplasia, but these are only in the initial stages.
#44 Pituitary Dwarfism | Encyclopedia.com
https://www.encyclopedia.com/medicine/diseases-and-conditions/pathology/pituitary-dwarfism
A careful balancing of all of the hormones produced by the pituitary gland is necessary for patients with panhypopituitarism. […] The prognosis for each type of dwarfism varies. Dwarfism due to only growth hormone deficiency has a different prognosis. […] If the individual is lacking only growth hormone then growth hormone replacement therapy can be administered.
#45 Juvenile-Onset Panhypopituitarism in Dogs – Endocrine System – Merck Veterinary Manual
https://www.merckvetmanual.com/endocrine-system/the-pituitary-gland/juvenile-onset-panhypopituitarism-in-dogs
The second most common cause of pituitary dwarfism is craniopharyngioma, a benign tumor derived from the oropharyngeal ectoderm of the Rathke pouch. […] Craniopharyngiomas cause subnormal secretion of growth hormone (GH), which results in dwarfism. […] Lifespan is shortened because of resulting secondary endocrine dysfunction, including hypothyroidism and hypoadrenocorticism. […] The activity of insulin-like growth factor 1 (IGF-1; formerly called somatomedin C) is low in dwarf dogs. […] Assays for IGF-1 provide an indirect measurement of circulating GH activity in dogs with suspected pituitary dwarfism. […] Basal concentrations of circulating canine GH are reported to be detectable but low in pituitary dwarfs, and they do not increase after a provocative test for secretion that follows clonidine injection, as they do in healthy dogs.
#46 A to Z: Pituitary Dwarfism | Dayton Children’s Hospital
https://www.childrensdayton.org/kidshealth/a/az-pituitary-dwarfism
Pituitary dwarfism is treated with regular injections of synthetic human growth hormone before a child’s growth plates have joined together. It can be difficult to manage, however, and success rates vary. […] Children with pituitary dwarfism have normal intelligence and with early detection and treatment, many of them can also reach a normal height.
#47 Mechanisms and pathways of growth failure in primordial dwarfism
https://pmc.ncbi.nlm.nih.gov/articles/PMC3197200/
Overall, the most plausible unifying hypothesis is that by reducing the efficiency of cell cycle progression, primordial dwarfism genes act to reduce the total cell number generated during development, leading to reduced tissue and organism size. […] As a whole, the primordial dwarfism genes are involved in cell cycle progression, with organism size most likely reduced in these conditions through reduced cell number.
#48 Dwarfism – Wikipedia
https://en.wikipedia.org/wiki/Dwarfism
Dwarfism can result from many medical conditions, each with its own separate symptoms and causes. Extreme shortness in humans with proportional body parts usually has a hormonal cause, such as growth hormone deficiency, once called pituitary dwarfism. Achondroplasia is responsible for the majority of human dwarfism cases, followed by spondyloepiphyseal dysplasia and diastrophic dysplasia. […] The most recognizable and most common form of dwarfism in humans is achondroplasia, which accounts for 70% of dwarfism cases, and occurs in 4 to 15 out of 100,000 live births. […] Achondroplasia is an autosomal dominant disorder caused by the presence of an altered allele in the genome. If a pair of achondroplasia alleles are present, the result is fatal, usually perinatally. Achondroplasia is a mutation in the fibroblast growth factor receptor 3. In the context of achondroplasia, this mutation causes FGFR3 to become constitutively active, inhibiting bone growth.
#49 Osteochondrodysplasias (Osteochondrodysplastic Dwarfism) – Pediatrics – Merck Manual Professional Edition
https://www.merckmanuals.com/professional/pediatrics/connective-tissue-disorders-in-children/osteochondrodysplasias-osteochondrodysplastic-dwarfism
Osteochondrodysplasias involve abnormal bone or cartilage growth, leading to skeletal maldevelopment, often short-limbed dwarfism. […] The basic genetic defects have been identified in most of the osteochondrodysplasias. The mutations typically cause perturbation of function in proteins involved in growth and development of connective tissue, bone, or cartilage. […] Dwarfism is markedly short stature (adult height 4 ft 10 in) frequently associated with disproportionate growth of the trunk and extremities. […] There are many types, which differ widely in genetic background, course, and prognosis, but all cause markedly short stature and often disproportionate growth of the trunk and extremities. […] Growth hormone treatments are typically ineffective.