HLA class II alleles in the DQA1, DQB1, DRB1, and DPB1 genes were investigated in Japanese patients with myasthenia gravis (MG) by digestion of polymerase chain reaction amplified DNAs with allele specific restriction endonucleases (PCR-RFLP). A significantly higher frequency of DQB1*03, which includes *0301, *0302, *0303 and determines the serological DQ3 specificity, was observed in female patients less than 30 years in age at onset of disease compared with healthy controls (90.5 vs. 53.2%). This study also confirms the high incidence of DPB1*0201 in early-onset female patients compared to the controls (85.7 vs. 40.3%). Moreover, 81.0% of the early onset female patients were found to carry both DQB1*03 and DPB1*0201, compared to 17.7% of the controls. Since DQB1*03 and DPB1*0201 are not in linkage disequilibrium, both these alleles are supposed to be synergistically involved in disease development in early-onset female MG. In contrast, no obvious association of HLA-DQA1, DQB1, DRB1 and DPB1 alleles with either late-onset patients or patients with thymoma was observed. Clearly, the genetic background of Japanese females with early onset MG is different from that of other patients with MG.

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To elucidate the clinical characteristics and pathogenesis of scleroderma-rheumatoid arthritis (SSc-RA) overlap syndrome, we analyzed the clinical features of 5 patients with SSc-RA overlap. Their HLA phenotypes and genotypes were also determined. Generalized skin sclerosis, severe seropositive polyarthritis, pulmonary fibrosis, anti-topoisomerase I antibodies, and HLA-DR4,53;DQA1*0301;DQBl*O4 haplotype were observed in all of the patients. Similar clinical features were recognized in most of the 10 cases reported previously. Our case studies indicate that SScRA overlap may be a distinct entity.

A 22-year-old female with Raynaud's phenomenon, swollen hands and a high titer ofanti-RNP antibodies developed fever and myositis. Prednisolone (40 mg/day) was considered effective for myositis since circulating myogenic enzymes rapidly decreased. However, she suddenly developed respiratory distress with bilateral pulmonary infiltrates and bloody sputum. Under the diagnosis of alveolar hemorrhage (AH), intravenous methylprednisolone pulse therapy was given, but she died of respiratory failure. Autopsy findings demonstrated massive AH with hematoma formation, and myositis in the iliopsoas muscle. Depositions of immunecomplex and vasculitic lesions were not recognized in her lungs. (Internal Medicine 37: 554-560, 1998)

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