User:Pablosuarez ucsf/Clubfoot

Genetics[edit]
Clubfoot can be diagnosed prenatally as early as 13 weeks of gestation via ultrasound. According to the Society of Maternal-Fetal Medicine, a diagnostic testing for genetic causes is recommended when clubfoot is diagnoses prenatally. If prenatal screening is suspicious for aneuploidy, karyotype analysis or chromosomal microarray (CMA) may be performed. However, if patients decline diagnostic testing, Cell-Free DNA is another screening option to identify high-risk pregnancies for aneuploidy and it is not diagnostic. The incidence of chromosomal abnormalities in fetuses with prenatal diagnosis of clubfoot is relatively low. Aneuploidy is detected on karyotype analysis in 3.6% of cases and the abnormalities most prevalent are trisomy 21 and 18.

If one identical twin is affected, there is a 33% chance the other one will be as well.

Mutations in genes involved in muscle development are risk factors for clubfoot, specifically those encoding the muscle contractile complex (MYH3, TPM2, TNNT3, TNNI2 and MYH8). These can cause congenital contractures, including clubfoot, in distal arthrogryposis (DA) syndromes. Clubfoot can also be present in people with genetic conditions such as Loeys–Dietz syndrome and Ehlers-Danlos syndrome.

Genetic mapping and the development of models of the disease have improved understanding of developmental processes. Its inheritance pattern is explained as a heterogenous disorder using a polygenic threshold model. The PITX1-TBX4 transcriptional pathway has become key to the study of clubfoot. PITX1 and TBX4 are uniquely expressed in the hind limb.