The non-synonymous C1858T substitution in the PTPN22 gene is associated with susceptibility to the severe forms of alopecia areata.

Alopecia areata is an acquired hair loss disorder resulting from an immunologically- mediated attack on hair follicles and autoimmunity may play a part in its pathogenesis. The non-synonymous C1858T substitution in the PTPN22 gene, which encodes lymphoid protein tyrosine phosphatase, has been shown to be associated with susceptibility to autoimmune disorders. In this study, the objective was to ascertain whether or not the disease-associated 1858T (W620) allele was associated with alopecia areata.