HLA-antigen frequencies in patients with progressive systemic sclerosis and morphea.

A possible HLA disease association was investigated in 40 patients (38 female, 2 male) with progressive systemic sclerosis (PSS) and 42 patients (32 female, 10 male) with morphea. The HLA A, B, C, DR phenotypes of patients were compared with 193 healthy controls. The following relative risk (RR) values were determined in PSS: A1 (1.38), A2 (1.39), B8 (1.67), B15 (3.22), DRw8 (6.30) and in morphea patients: A3 (1.43), B7 (1.39), B40 (1.81), Bw60 (2.49), DR2 (2.38) and DRw8 (2.55), indication a relatively weak, HLA-linked genetic predisposition for the manifestation of the disease. The HLA "risk" antigens for the two clinically different subtypes of the disease are also different: raised A1/B8 frequencies, like in our PSS group, correlate with a high, pathological immune response (autoimmune disorders). In contrast, A3/B7/DR2 prevalence, like in our morphea group, correlates with a low immune response. HLA typing may contribute to clinical differential diagnosis and possibly also prognosis.