Syndactyly

SYNDACTYLY (from Greek syn- together and daktylos- finger), a developmental deformity in which there is fusion of the fingers of the hand or foot, for example, of the little finger with the ring finger, of the ring finger with the middle finger, etc. At the site of fusion, a skin membrane resembling that of a swimming membrane in some birds is formed. The cause of S. is not fully elucidated. In a number of cases, it is associated with amniotic threads and constrictions during intrauterine life, but in most cases, no traces of these threads can be found and a hereditary origin of the deformity is assumed, all the more so since cases of S. (as such, or in combination with other finger and hand deformities) are observed in the corresponding offspring or among ancestors. Therefore, the view is expressed that S. may be one of the mutations of the extremities, just as the opposite condition of polydactyly. See also Hand, Adactyly. j S. is one of the few characteristics of the organism with respect to which the assumption of so-called "one-sided inheritance" (one-sided inheritance) is highly probable. Cases of inheritance of S. only through the male line have been described, and women are not even carriers of the corresponding gene. From this, the conclusion is drawn about the localization of the S. gene in the Y-chromosome.