Congenital limb malformations rank behind only congenital heart disease as the most common birth defects observed in infants. Finding genes that cause defects in human limb patterning should be straightforward but has been limited, in part, by the bewildering spectrum of phenotypes, which are difficult to separate into etiologically distinct disorders. One approach to the identification of relevant genes is to take advantage of unique extended kindreds in which a defect in limb patterning is segregating. Recently, a large Dutch family with ectrodactyly, ectodermal dysplasia, cleft palate, and urogenital defects (EEC) was described by Maas et al. We have studied this kindred and localized a gene causing EEC to a locus on chromosome 19, in a region defined by D19S894 and D19S416. A second extended kindred with EEC does not map to this locus, indicating that EEC is a genetically heterogeneous disorder. Growth and patterning of the limbs, teeth, hair, and genitourinary system are mediated in part by epithelial-mesenchyme inductive interactions. The identification of both the gene causing EEC and its mutation may further elucidate the general signals mediating inductive mechanisms.

Ectrodactyly has not previously been reported in children with Wolf-Hirschhorn syndrome (WHS). Based on this premise and the identification of an unbalanced translocation between chromosomes 4p15 and 10q25 in a fetus with ectrodactyly and hemimelia, a second locus for dominantly inherited split hand/foot malformation (SHFM3) was mapped to chromosome 10q24-q25. We present the clinical findings of an infant with WHS and SHFM and suggest that the presence of additional loci on 4p which modify/cause SHFM cannot be excluded.

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