[The clinical spectrum of focal dermal hypoplasia]

Focal dermal hypoplasia (FHD) is an X chromosomal dominant inherited disease with unknown gene defect. FDH is characterized by ectodermal and mesodermal malformations. It is thought to be lethal in males; however, males may survive as mosaics or possibly as Klinefelter syndrome (XXY). When mosaicism involves the gonads the disease may be transmitted from father to child. In females, the abnormal phenotype is thought to be expressed in a blaschkoid pattern because of random X chromosome inactivation. We have collected eight cases of which three were males. We present the typical clinical dermatological feature and draw attention to cases with minimal skin involvement.