Syndactyly is one of the two most common congenital hand abnormalities, the other being polydactyly (1, 2, 3). It occurs in about 1: 2,500 live births, more commonly in males, and is most often seen in the third web space (2, 4). The condition has a strong familial tendency and is bilateral in half of the cases (4, 2, 5). Inheritance is thought to be autosomal dominant with variable penetrance and expressivity, which may explain the male predominance (6).
Unlike secondary syndactyly, which occurs due to abnormal fusion of initially individualized fingers, primary syndactyly mainly occurs due to the failure of differentiation between adjacent digits, caused by the absence of apoptosis in the interdigital mesenchyme during the seventh and eighth weeks of gestation (7,8). Syndactyly may occur as an isolated event or it may be linked to other anomalies in the body, being known as syndromic syndactyly (7).