Syndactyly type 1 is a congenital limb developmental defect that involves webbing or joining of the fingers or toes. Syndactyly type 1 is the most common type of non-syndromic syndactyly. Individuals with syndactyly type 1 have webbing of the third and fourth fingers and/or between the second and third toes. Other digits may be involved, as well as the underlying bones. There are four different subtypes of syndactyly type 1, differentiated by slightly different hand and foot symptoms. Syndactyly type 1 may be inherited in an autosomal dominant manner and is suspected to be caused by a gene mutation on the long (q) arm of chromosome 2 between 2q34 and 2q36. Treatment usually involves surgery to separate the digits.