MYASTHENIA-GRAVIS AND HLA PHENOTYPES IN JAMAICANS

We determined HLA-antigen frequencies and corresponding relative risks (RR) in 30 jamaicans with myasthenia gravis (MG) and 40 normal controls. Using a microcytotoxicity assay and commercially prepared typing trays, we found that the strongest HLA associations with MG in jamaicans were with HLA-A2 (RR = 6.15), HLA-B8 (RR = 3.4), HLA-B13 (RR = 7.76), and DQw4 (RR = 3.8). After correction of the P value for the number of antigens tested, only HLA-A2 was statistically significantly increased in MG patients. There was a statistically significant negative association between MG and HLA-DR2, as well as HLA-A9 and -B5. No correlation was observed between HLA phenotype, thymic disease, clinical grades, or disease course. HLA-A2 and sex were independent risk factors for MG, female patients having a higher risk (RR = 5.8). Further studies using larger patient and control groups, locally derived typing sera, and DNA probe analysis are indicated.