Although limb defects associated with other congenital anomalies are rarely studied, they may provide insights into limb development that may be useful for etiologic studies and public health monitoring. We pooled data from 11 birth defect registries that are part of the International Clearinghouse for Birth Defects Monitoring Systems. We identified 666 infants, born from 1983 through 1993, who had a non-syndromal limb defect plus at least one other major malformation (rate 12.9/100,000 population). We used observed/expected ratios and log-linear models to detect association patterns. We found that specific limb defects occurred with relatively distinct sets of malformations. Preaxial limb defects occurred more frequently with microtia, esophageal atresia, anorectal atresia, heart defects, unilateral kidney dysgenesis, and some axial skeleton defects; postaxial defects with hypospadias; transverse defects with craniofacial defects, micrognathia, ring constrictions, and muscular defects; intercalary defects with omphalocele; split hand/foot with encephalocele; and amelia with anorectal atresia, omphalocele, severe genitalia defects, unilateral kidney dysgenesis, gastroschisis, and ring constriction. Log-linear modeling identified higher order associations among some of these same malformations.

Pectoralis major muscle defect (PMD) was diagnosed in 27 infants from a series of 599,109 live births in South America (1/22,189). In all 27 cases the PMD was unilateral, mainly affecting the right side (20/27), and there were more male (19/27) than female cases. No familial cases and no parental consanguinity were recorded. A positive correlation was observed between PMD and sex hormone intake and vaginal bleeding in the first trimester of pregnancy. In 12 (1/49,925) of the 27 PMD cases hypoplasia and/or syndactyly of the ipsilateral hand was also diagnosed. The index-middle interdigital space was affected in all 11 cases with symbrachydactyly. Additional congenital anomalies were observed in 4/27 cases, and they were: hemangiomas, hypospadias, and clubfeet. Poland complex (12 cases), isolated PMD (15 cases), and isolated symbrachydactyly (18 cases), showed a similar pattern for symmetry, sidedness, syndactyly type, and sex ratio.

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