HLA-DR GENE-FREQUENCIES IN A ZAIREAN POPULATION WITH PARTICULAR REFERENCE TO RHEUMATIC DISEASES

Epidemiological studies have shown that rheumatic diseases such as rhe umatoid arthritis and systemic lupus erythematosus are uncommon in bla ck Africans, and in this population the prevalence and the clinical fe atures of these rheumatic diseases are variable, Environmental and gen etic factors have been pointed out to explain this variability. In the present study, HLA-DR genes have been determined in a Zairean populat ion in order to compare our results with those found elsewhere in othe r black populations of the same Bantu origin. Our results show that th e frequency of HLA-DR1 is higher than in Nigerians, Zimbabweans and Xh osas, the decrease in Xhosas being statistically significant (p < 0.00 6). The HLA-DR3 frequency is higher in Zaireans than in Nigerians but not significantly, while it is lower than in Xhosas (p < 0.003) and in Zimbabweans (not significant). The HLA-DR4 frequency is higher in Zai reans than in Nigerians but it is lower than in Xhosas and Zimbabweans ; the differences are not statistically significant. The HLA-DR8 frequ ency is lower in Zaireans than in Nigerians while it is higher than in Xhosas (p < 0.002) and in Zimbabweans (not significant). These data s uggest that genetic factors partly explain the clinical and epidemiolo gical variability of rheumatic diseases in black Africans.