[Hair anomalies in syndromic disorders].

Genetic diseases with hyper- and hypotrichosis are very heterogeneous, both clinically and genetically. This is especially true for ectodermal dysplasias but also for hereditary syndromes in which, beyond abnormal hair growth, other structures and organs are affected. In this review, we discuss distinct diseases with excessive and reduced hair growth, focusing on the clinical hallmarks and underlying genetic defects.