Clouston syndrome: an ectodermal dysplasia without significant dental findings.

The ectodermal dysplasias are a heterogeneous group of conditions primarily affecting the hair, teeth, nails, and skin, and are classified according to the tissue(s) affected. The classification categories are: (1) abnormalities of hair, (2) dental defects, (3) abnormalities of nail morphology, and (4) dyshidrosis. Individuals are grouped according to defects present with findings from two or more categories required for diagnosis. As this classification method is based on phenotype, variable expression or small family size may well have an impact on diagnosis. We report a four-generation family with a hair-nail (1-3) dysplasia with nail morphology that is typical of Clouston syndrome. All affected relatives have thick, discolored, hyperconvex nails with onycholysis, varying degrees of hair involvement, and are hidrotic. They lack hyperkeratosis and multiple caries as originally described in Clouston syndrome. We propose that morphologic abnormalities of the teeth may not occur in the phenotype of Clouston syndrome and that it can be considered a hair-nail (1-3) dysplasia.