Mental retardation in a boy with anterior cervical hypertrichosis.

Anterior cervical hypertrichosis (ACH) is a rare form of localized hypertrichosis with 15 previously reported cases. ACH has been considered to be a dominant phenotype, either X-linked or autosomal [OMIM 600457]. ACH was associated with hereditary motor and sensory neuropathy (HMSN) in one family, in which the proband also exhibited severe chorioretinal degeneration and optic atrophy, probably as a different entity [OMIM 239840]. A Mexican boy with congenital ACH associated with moderate mental retardation, abnormal EEG, mild microcephaly, hypertrichosis on the back, and hallux valgus is presented here. An equal sex ratio found in 16 reported cases as well as the suggestion of a paternal age effect in one report appear most consistent with an autosomal dominant mode of inheritance for this trait. It remains unclear if isolated ACH, ACH-HMSN, or other associated findings reported in patients with ACH, including unusual features found in our case, are part of ACH or fortuitous associations, due to the small number of affected patients and different ascertainment biases present in previous reports.