Association of HLA antigens with myasthenia gravis in Chinese on Taiwan.

HLA phenotypes were studied in 82 Chinese patients with myasthenia gravis (MG) and 202 healthy controls, using standard microcytotoxicity assay. The patients showed significant increase in HLA-Bw46 (46.3% vs 17.3%, chi 2 = 25.7, p less than 0.001), HLA-DR9 (56.1% vs 15%, chi 2 = 35.7, p less than 0.001) and HLA-DQw3 (89% vs 63.6%, chi 2 = 15.9, p less than 0.001). The HLA-DR3 was decreased (2.4% vs 32.7%, chi 2 = 27.0, p less than 0.001). Both HLA-Bw46 and -DR9 were increased in all subgroups except the over 40 at age of onset group. In thymectomised patients, no association with HLA antigen was found in the thymoma group, whereas both involuted and hyperplasic thymus groups had HLA DR9 association and only the hyperplasic thymus group showed HLA Bw46 association. No association with HLA antigens was noted in patients with low antibody titer, however, patients with antibody titers between 0.2 to 2 n mole/1, had an association with HLA Bw46 and DR9. The HLA DQw3 was associated with the group of female MG patients, age onset below 10 and with ocular myasthenia. Finally, the HLA A2, Bw46 and DR9 combination was also significantly increased in patients [24.3% (20/82) vs 7.4% (8/107), chi 2 = 10.5, p less than 0.001], especially in the subgroup of male MG, age onset below 10 and with ocular myasthenia.