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 VSports手机版. 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. .