Short anagen syndrome.

Short anagen syndrome (SAS) is a recently described disease, but is rarely reported in the literature probably because of its under-recognized status. It is characterized by the inability to grow long hair because of an idiopathic short anagen phase. The condition is not associated with hair shaft fragility or hair unruliness. The patients complain of abnormally short scalp hair and report that they never had a haircut. The condition is benign and most of the reported cases had no associated systemic diseases or skin disorders. Hair length tends to improve spontaneously after puberty. The main differential diagnoses include loose anagen hair syndrome (LAS).