Associated anomalies in individuals with polydactyly

An epidemiological analysis of the association of polydactyly with other co ngenital anomalies was performed in 5,927 consecutively born polydactyly ca ses, They were grouped into three categories: duplicated fifth digit, dupli cated first digit, and rare polydactylies; also into isolated or associated groups, if other birth defects were or were not observed in the same infan t. Associated cases were further subdivided into: combined, if the other de fect was a limb defect; syndromic, if a non-limb defect constituted a recog nized causal or pathogenetic entity; and MCA, if a non-limb defect did not constitute a recognized entity, In 14.6% of the 5,927 polydactyly cases stu died, polydactyly was not the only congenital anomaly. This associated prop ortion was minimal for postaxial (11.8%), intermediate for preaxial-I (20.0 %), and maximal for rare polydactyly (54.9%). Duplication of the fifth toe plus syndactyly of fourth and fifth toes, as well as other syndactylies adj acent to the duplicated digit is the most frequent type. Syndactyly of four th and fifth toes was also combined with a duplicated fifth finger, suggest ing the existence of an arrested or amputated in utero sixth toe. Polydacty lies are rarely associated with other congenital anomalies except in recogn izable syndromes. When syndromes are excluded, most of the significant posi tive associations disappear. Trisomy 13, Meckel, and Down syndrome explaine d 255 of the 338 syndromic polydactyly cases. Down syndrome is strongly ass ociated with first-digit duplication, and negatively associated with postax ial polydactyly. The latter could not be explained by maternal age differen ces among Black and non-Black case sub-sets. Am. J. Med. Genet. 80:459-465, 1998. (C) 1998 Wiiey-Liss, Inc.