Hypohidrotic ectodermal dysplasia: prenatal diagnosis by three-dimensional ultrasonography.

Ectodermal dysplasia is the term used to describe a group of rare congenital anomalies characterized by abnormal development of 1 or several ectoderm-derived tissues. At least 154 different types, divided into 11 clinical subgroups, have been recognized. Among them, the hypohidrotic type is the most common form, with an incidence of 1 per 10,000 to 1 per 100,000 live births. This condition, originally known as anhidrotic ectodermal dysplasia because of the notable reduction of sweat gland function, is clinically characterized by hypohidrosis, hypotrichosis, and hypodontia. Most cases are inherited as an X-linked recessive trait, with the gene responsible being mapped to Xq12-q13.1. The autosomal recessive and dominant patterns of inheritance have also been documented. Prenatal diagnosis of this condition has been reported previously in high-risk pregnancies on the basis of histologic analysis of fetal skin obtained by second-trimester fetoscopy-guided skin biopsy. DNA-based linkage analysis has also made the diagnosis possible with the use of chorionic villi in the first trimester. In this report, we describe noninvasive prenatal diagnosis of hypohidrotic ectodermal dysplasia in a pregnancy at risk for this condition. The diagnosis was achieved by identification of the distinct facial features at 30 weeks' gestation on three-dimensional (3D) ultrasonography.