Mosaic Expression of Hypohidrotic Ectodermal Dysplasia in an Isolated Affected Female Child

Background: Hypohidrotic ectodermal dysplasia (HED) is characterized by hypotrichosis, hypodontia, onychodysplasia and, as the most striking feature, hypohidrosis. The X-linked recessive form of HED, also known as Christ-Siemens-Touraine syndrome, is the most frequent and widely documented form. A clinically identical autosomal recessive form of HED has also been described. Because of the X-linked mode of inheritance, nearly all observations have concerned pedigrees of predominantly male affected patients. We present a rare isolated affected female child with a mosaic expression of HED. We attempted to assess the mode of inheritance in our case. Observations: We documented the characteristic clinical appearance in our proband, as well as the scanning electron microscopic findings regarding the hair. The starch-iodine test results in this patient revealed the clinical expression of HED in a mosaic fashion, running along the Blaschko lines. Conclusions: The starch-iodine test results proved to be useful in the assessment of carriers of X-linked HED, and our proband was considered to an isolated affected female with a mosaic expression of HED. (Arch Dermatol. 1994;130:1421-1424)