Tetra-amelia syndrome causes
Researchers have found a mutation in the WNT3 gene in people with tetra-amelia syndrome from one large family. The WNT3 gene is part of a family of WNT genes that play critical roles in development before birth.
The protein produced from the WNT3 gene is involved in the formation of the limbs and other body systems during embryonic development. Mutations in the WNT3 gene prevent cells from producing functional WNT3 protein, which disrupts normal limb formation and leads to the other serious birth defects associated with tetra-amelia syndrome.
In other affected families, the cause of tetra-amelia syndrome has not been determined. Researchers believe that unidentified mutations in WNT3 or other genes involved in limb development are probably responsible for the disorder in these cases.
Signs and symptoms
Eyes. Microphthalmia, cataract, microcornea, coloboma, palpebral fusion
Ears. Absence of external ears (microtia), low-set ears
Nose. Single naris, choanal atresia, prominent nose, absence of nose
Mouth. Cleft lip/cleft palate, high and narrow palate, macrostomia, micrognathia
Agenesis of kidney
Rudimentary ovary and salpinx
Persistence of cloaca
Atresia of vagina
Atresia of anus
Atresia of urethra
Absence of external genitalia
Absence of scrotum
Intra-abdominal location of testis
Hypoplasia/aplasia of lungs, bilobular right lung
Hypoplasia/aplasia of pulmonary vessels
Ventricular septal defect
Small right heart
Mitral valve aplasia
Hypoplasia/absence of pelvic bones
Absence of vertebra
Absence of rib
Central nervous system
Agenesis of olfactory nerves
Agenesis of optic nerves
Agenesis of corpus callosum
Absence of nipples
Agenesis of suprarenal gland
Agenesis of spleen.