[Clinical characteristics and genetic background of secondary amyloidosis associated with rheumatoid arthritis in Japanese].

In order to examine the clinical characteristics and genetic background of secondary amyloidosis associated with rheumatoid arthritis, we analyzed clinical features and HLA typing of 85 patients in a multicenter study. Eighty-five patients with secondary amyloidosis associated RA were studied. The diagnosis of secondary amyloidosis were made on histological findings by biopsy or autopsy. The most common biopsy site was gastrointestinal tract (79.5%). Clinical symptom and the frequency at the time of diagnosis were; diarrhea (35 cases), abdominal pain (22 cases) and vomiting and nausea (16 cases). Abnormalities and the frequency in a laboratory test included proteinuria (49 cases), increased serum creatinine (32 cases), anemia (30 cases) and hematuria (15 cases). Twenty-eight patients were dead and 57 patients were alive at the time of the study. The average duration between diagnosis of amyloidosis and death was 19.4 +/- 18.5 (SD) months among the dead patients. The average duration after diagnosis of amyloidosis was 24.2 +/- 19.5 (SD) months in surviving patients. The causes of death were renal failure complicated with heart failure (6 patients), heart failure alone (3 patients) and renal failure alone (2 patients). Fifty-nine patients in the control group who were negative to amyloid deposition on biopsies at more than one site in the gastrointestinal tract, were clinically compared with patients in the amyloidosis group. No difference were noted in the age of RA occurrence and the stage between the two groups. As to the class, however, the number of patients with severe functional disorder (class 3 or severe) was larger in the amyloidosis group. There were no significant difference between the two groups in Lansbury's activity index. On hematology, biochemistry and urinalysis, the incidences of increased white blood cell count, anemia, increased platelet count, increased serum creatinine, hypoproteinemia, hypoalbuminemia, increased IgA, and increased urine and blood BMG were statistically significantly higher in the amyloidosis group than in the control group. HLA-A, -B, -C, and DR-locus antigens were compared in the 53 patients in the amyloidosis group and in the 59 subjects in the control group. There were no significant differences in frequency of HLA-A, and -B antigens between two groups. Frequency of CW7 antigen was significantly decreased in the amyloidosis group (13.2%) than in the control group (39.0%). Frequency of DR1 antigen was decreased in the amyloidosis group (3.8%) than in the control group (22.0%), although the difference was not significant. These findings suggest the possible involvement of genetic factors in the occurrence of amyloidosis. It is suggested that the occurrence of amyloidosis is suppressed by some genes which are linked with CW7 antigen.