To determine whether genetic factors could be involved in the pathogenesis of rheumatic heart disease, we performed HLA-A and HLA-B typing in 120 black patients with severe chronic rheumatic heart disease requiring cardiac surgery, and HLA-DR and HLA-DQ typing in 103 and 97 of these patients, respectively. The HLA typing was done by a standard microlymphocytotoxicity method. Patients were 12 to 60 years old (mean 27.6 ± 14.5). No differences in HLA-A, HLA-B, and HLA-DQ frequencies between patients and controls were noted. HLA-DR 1 antigen was present in 12.6% of patients compared with 2.7% of normal control subjects (corrected p<.045; relative risk = 5.2) and the HLA-DRw6 antigen was present in 31.1% of patients compared with 15% of control subjects (corrected p<.045; relative risk = 2.6). These findings suggest that genetically determined immune-response factors may play a role in the pathogenesis of severe chronic rheumatic heart disease.

Five hundred patients with cancer were tested for 32 HLA antigens and the antigen frequencies compared with those of 5 0 0 control subjects matched for race, sex and age. Although the overall frequencies showed no significant differences, detailed analysis with regard to site of cancer, age and the number of antigens detected at each locus revealed significant differences. Phenotype tables and haplotype frequencies have been included.

The H L A 5 antigen has a higher frequency in the Indian population than in either the Caucasian or Bantu populations of South Africa. Ninety-five Asian Indians were tested by microcytotoxicity using 34 anti-HL-A5 and nine anti-W5 sera. T h e results confirm the heterogeneity of the HL-A5 antigen and show that it may be subdivided into a t least four parts. The Indian population of South Africa is here subdivided into four groups. The HL-A antigen frequencies in each group are compared, and haplotype frequencies and gametic associations (delta values) have been calculated. The genetic distances ( f ) between these groups and between Indians, Caucasians and Bantu also are calculated. The results may indicate a differential selection with respect to the HL-.4 polymorphism.

The Indian population of South Africa has been found to have a higher frequency of the antigens HL-A5 and W5 than do either Caucasians or Bantu. Some antisera that appeared to be good anti-HL-A5 or anti-W5 in South African Caucasians gave anomalous results when tested in Indians. The sera of 1,000 Indian women were tested for lymphocytotoxic antibodies and those sera found to contain antibodies were tested in parallel with known antisera against the cells of 150 Indians.We tested for 10 antigens at the first locus, HL-A1, 2, 3, 9, 10, 11, W28, W19, Te63 ( = W19-1) and Te66 ( = W19-4) and a t the second locus for 12 antigens, HL-A5, 7, 8, 12, 13, W5, W14, W15, W17, W22, W27 and W10.The frequency of HL-A1 is 22 96, which agrees with the Caucasian origin of the Indian population. There apparently are subdivisions of H L A 5 and W5, and one serum was found to be a "short" W10. HL-A11 has a relatively high frequency in Indians and may also be subdivided.

The frequency of HLA‐A, B, C and DR tissue antigens in 103 Indian men aged 40 years or under who had experienced a myocardial infarction was compared with the frequency in 760 healthy Indian controls. No significant differences in antigen frequencies were found. The findings in this study provide no support for either a genetic or an immunological basis for myocardial infarction in young Indian men.