title: Patterns of combined limb malformations.
abstract: Seven different limb malformations types were defined in 544 affected newborns, apparently free from other anomalies, obtained from a series of 297,299 livebirths. These seven malformation types were: polydactyly, limb reduction, brachydactyly, symphalangy, syndactyly and split hand/foot. One anomaly type was present in 472 newborns (1.58/1,000) and two or three in 72 (0.24/1,000). The observed combinations of two or three limb malformation types cannot be explained as chance association. Therefore, a common etiopathogenic mechanism has to be considered when two or more limb malformation types are combined in a given individual. The most frequent observed combinations were: reduction-brachydactyly, reduction-syndactyly, brachydactyly-syndactyly, polydactyly-syndactyly, and reduction-brachydactyly-syndactyly. Based on affected limb distribution, sex ratio, and familial recurrence rates, it is suggest that a reduction anomaly is the primary component in all tested combinations while syndactyly tends to be a secondary one when combined with any other limb anomaly type.
mesh_terms: D000015:Abnormalities, Multiple / Q000453:epidemiology / Q000235:genetics; D001132:Arm / Q000002:abnormalities*; D000013:Congenital Abnormalities / Q000145:classification / Q000453:epidemiology / Q000235:genetics; D004480:Ectromelia / Q000453:epidemiology / Q000235:genetics; D005260:Female; D005385:Fingers / Q000002:abnormalities; D006801:Humans; D007231:Infant, Newborn; D007866:Leg / Q000002:abnormalities*; D008297:Male; D012744:Sex Ratio; D013020:South America; D013576:Syndactyly / Q000453:epidemiology / Q000235:genetics