[Anhidrotic ectodermal dysplasia. Report of a rare mutation in EDA1]

Anhidrotic ectodermal dysplasia is a rare inherited disorder seen mainly in the X-linked recessive form. We report the case of a Lebanese family in which the mother transmitted an uncommon missense mutation to three of her sons.

A 23-year-old patient presented with keloids in nodular acne. The physical examination showed fine and sparse hair, thick everted lips and dental defects. A detailed history revealed congenital anhidrosis. The patient's, seven-year-old and four-year-old brothers had the same characteristic facial morphology and were also presenting anhidrosis. The mother had hypodontia. The parents, though not consanguineous, were from the same village. Genetic testing with sequencing of the EDA1 gene revealed a missense mutation affecting codon 155.

Ectodermal dysplasias are currently found in more than 150 syndromes. The patient's history and the clinical signs suggest the X-linked recessive form of anhidrotic ectodermal dysplasia due to a mutation in EDA1 gene encoding the ectodysplasin. The mutation found in this family is very rare and was mentioned once in a study on splicing forms that permit detection of all EDA1 mutations. Besides, this patient tolerated oral isotretinoin perfectly well, unlike another case reported once in the literature. Finally, genetic counselors must inform carrier mothers of the high recurrence rate among male offspring.