Heritable factors distinguish two types of alopecia areata.

Alopecia areata (AA) has been shown to be associated with the inheritance of HLA class II alleles. HLA-DQ3 appears to be the general susceptibility allele for AA. Patients with long-standing disease patterns, namely, longterm patchy AA and long-term alopecia totalis and alopecia universalis (AT/AU), can be differentiated by their particular HLA associations. Long-standing AT/AU patients have unique and highly significant associations with HLA antigens DR4, DR11, and DQ7. A complex of early onset, disease severity, family incidence, and associations with HLA DR antigens are characteristic of long-standing AT/AU as distinct from long-standing patchy AA.