Sixty‐one patients in the Dundee area suffering from psoriasis were typed for HLA—A and HLA—B antigens. On the basis of the typing results, the patients were divided into three groups, and studied with respect to sex, age of onset and familial incidence of the disease. The frequency of HLA—A1 appeared to be increased and HLA—B7 decreased but HLA—B13 and HLA—B17 were highly significantly increased (P < 10−6 and P < 10−10 respectively) in the psoriatic group compared to 204 controls. Of particular interest was a highly significant association of HLA—A1 with HLA—B17 in psoriatic patients. Family studies showed HLA—B17 to be a useful genetic marker for psoriasis in the families of B17 positive patients. Considerations of age of onset, familial incidence and typing data suggest that there is heterogeneity of genetic susceptibility to psoriasis and that one probable mechanism is the dominant inheritance of a “disease allele” in linkage disequilibrium with the allele coding for HLA—B17.
We describe a variant HLA-B*39 allele present in two individuals from Oman, which has been officially named HLA-B*3921. In addition we confirm the existence of HLA-B*4415, an allele closely related to HLA-B*4501 differing only at the Bw4/Bw6 epitope.
Aim-To determine the presence of HLA antigens in people with blinding trachoma. Methods-Fifty Omanis with blinding trachoma were serologically typed for HLA A, B, C, DR, and DQ antigens and DNA typed for class II DR and DQ alleles and compared with a population of 100 healthy controls.
Results-2 analysis of serological reactions did not reveal any significant diVerences in HLA antigen frequencies after correction of probability, although DR4, DR7, and DR53 were completely absent in the patients and all of the patients were HLA DQ1 positive. In the case of DQ1 the relative risk was 22.6 (95% confidence interval of 20.7-24.7). Class II DNA low resolution DR typing showed a significant increase in HLA DR16 (p c = 0.036, relative risk = 3.8) and a significant decrease in HLA DR53 (p c = 0.018, relative risk = 0.05 ). Conclusion-The finding that HLA DR16 (a DR2 subtype) is associated with susceptibility to blinding trachoma, a disease that is caused by an intracellular microorganism, is consistent with reports of an HLA DR2 association with leprosy and tuberculosis, diseases also caused by an intracellular micro-organism. Similarly, resistance to leprosy is associated with HLA DR53 as is the case with blinding trachoma described here. It is postulated that HLA DR2 or subtypes in association with HLA DQ 1 may enable an intracellular micro-organism to enter the cell or are involved in presentation of peptides derived from intracellular micro-organisms to T lymphocytes initiating a delayed hypersensitivity or autoimmune reaction. These findings are the first report that genetic factors are of major importance in the development and protection against blinding trachoma. (Br J Ophthalmol 1997;81:431-434)
Background: This is the first comprehensive report of HLA antigens in Omanis, and the first application of HLA sequence-specific primer (SSP) DNA typing in a Gulf population. The objective was to compare the findings with other Gulf populations and assess their implications for disease association. Patients and Methods: HLA\ typing was carried out on 321 healthy Omanis. One hundred and twenty-six of these were typed for Class II antigens by low-resolution SSP DNA typing. The results were compared with other HLA antigen frequencies recorded from Kuwait and Saudi Arabia. Results: The Omani population was characterized by a very high incidence of HLA-DR2 (66%), with associated HLA-DQ1 (76%) and a reduced incidence of DR4, DR7 and DR53. The incidence of DR2 is the highest recorded worldwide. HLA-A11, A32, B17, B35 and B40 were significantly higher than in Kuwait and Saudi Arabia, and A9, B21(B50) significantly lower (P c <0.05). HLA-B27 is very low in the Omani population (0.3%). The high incidence of HLA-DR2 in Oman and disparities in the frequency of other antigens would indicate that there has not been any significant migration from northern Arabia. Class II DNA typing revealed that DR16 was the predominant split of DR2 (63%), with DR15 being 18% and both DR15 and 16 being found in 6%, giving a total of 87% for "DR2"-associated antigens (serology of the same individuals gave a DR2 incidence of 74%). The major disparity between serology and DNA typing was in the definition of DR4 (serology 8%, DNA 14%) and DR51 (53% vs. 70%)\, Conclusion: The frequency of many HLA antigens in Omanis differs significantly from frequencies found in the populations of Kuwait and Saudi Arabia, possibly reflecting different migration patterns. The high incidence of HLA-DR2 in Oman may have important implications for disease association.
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