A Four Generation Hidrotic Ectodermal Dysplasia Family: An Allelic Variant of Clouston Syndrome?

The study described a four-generation Scottish family with hidrotic ectodermal dysplasia, primarily affecting teeth, skin, and hair. Key features included hypo- or oligodontia by late adolescence, thin and slow-growing scalp hair, and scanty body hair, with improved hair quality in adult females during pregnancy. Some women exhibited flexural acanthosis nigricans, and heat tolerance varied among individuals. Light microscopy revealed hypoplasia of pilosebaceous units, and scanning electron microscopy showed abnormal hair cuticles, indicating a keratin structure defect. Despite these symptoms, nails were normal, and relative macrocephaly due to cranial hyperostosis was variably present. The family shared overlapping features with Clouston syndrome, but differed in the severity of alopecia and the presence of palmarplantar hyperkeratosis.