Ectodermal dysplasias form a heterogenous group of disorders characterized by anomalies of structures arising from the ectoderm. ECTD8 is an autosomal recessive condition in which affected patients display abnormal development of hair, teeth and nails.
The condition has been mapped to an 8 Mb locus on the long arm of chromosome 18. However, the causal gene has not yet been identified.
Fried et al. (1977) described two double first cousins, from the Egyptian Karaite community, who presented with partial adontia, conical peg-shaped teeth, fine short hair, and eversion of lips. Both children were born of consanguineous unions, and teh parents were normal.
Mégarbané et al. (1998) described two affected siblings born to second-cousin consanguineous parents. The patients showed severe hypodontia, fine hair and dysplastic nails. Seven other cousins and the patients' grandmother were all similarly affected, pointing to an autosomal recessive mode of inheritance.