Epidemiology of human leukocyte antigens among omani population

Abstract

Oman is located on the Southeastern coast of the Arabian Peninsula, and its population has high levels of consanguinity. Human leukocytic antigen (HLA) typing analysis in human population holds unexploited potential for elucidating the genetic causes of human disease and possibly leads to personalized medicine. This is a retrospective, descriptive study evaluating HLA frequencies of Omani individuals who underwent workup for kidney transplantation at the Royal Hospital (RH) from 2005 to 2016. Data on 870 subjects were collected from the Oman kidney transplant registry at RH as well from electronic medical record system. The mean age (standard deviation) years for the cohort were 33.2 (13.0). Males constituted 56.3% (490) while females constituted 43.7% (380). Seven HLA-A alleles accounted for more than 70% of the total alleles. Of which, HLA-A2 contributed the highest frequency (24%), followed by HLA A11 (9.4%), and A32 (8.1%). Ten alleles accounted for 70% of HLA-B alleles. Of which, HLA-B51 was the most common (18.9%), followed by HLA-B-35 (13.6%), and HLA-B8 (7.9%). Seven HLA-DRB1 alleles accounted for more than 70% of the total HLA DRB1 alleles, of which HLA- DRB1*16 contributed the highest frequency (29.56%). This was followed by HLA-DRB1*03 (14.57%) and HLA-DRB1*11 (9.48%). While three alleles accounted for more than 75% of the total HLA DQB1alleles. Of which, HLA-DQB1*05 contributed the highest frequency (37.56%). This was followed by allele HLA-DQB1*02 (26.48%) and HLA-DQB1*03 (17.18%). This study showed considerable heterogeneity in both HLA Class I and Class II antigens, which reflects admixture of our population with rest of old world countries. Despite the high levels of consanguinity, this population is genetically highly heterogeneous. These findings may be useful for transplantation programs, noncommunicable diseases, epidemiology of HLA linked diseases, pharmacogenomics, and anthropology.

The Association of Human Leukocyte Antigens Complex with Type 1 Diabetes in the Omani Population

“…S 13 and K 71 association with T1D susceptibility was reported by others 23,24 and they were implicated in joint susceptibility to both T1D and autoimmune thyroid disease. 25 S 11 , S 13 and K 71 residues were also associated with risk to rheumatoid arthritis. 26 This suggests common disease mechanisms that operate irrespective of the presented self-peptides.…”

“…DRB1 S 13 is in pocket 4, K 71 in pockets 4 and 7, V 70 in pocket 4, S 11 in pocket 6, E 9 in pockets 6 and 9 and Y 30 in pocket 6. As S 13 , V 70 and K 71 were associated with the strongest disease risk based on the P values and OR values, they might be the major contributors from pocket 4.…”

“…8 This was expected as the Omani population is genetically related to Arab, Mediterranean and West-Asian populations. 12,13,17 The HLA class I alleles associated with T1D susceptibility are B*08 (P=1.82E-02, OR= 2.51), B*58, P=2.86E-02, OR=2.47) and with protection is B*51 (P=1.82E-02, OR=0.41). These associated were reported in previous studies.…”

“…Therefore, we investigated the potentially associated residues in the HLA chains using the pocket test. The results showed that six residues (Glu-9, E 9 ; Ser-11, S 11 ; Ser-13, S 13 ; Tyr-30, Y 30…”

“…11 In Oman, the incidence of T1D is comparatively less than other Arabs, and also, ketoacidosis reported to be less in the Omani cases 11 . Although the Omani population is genetically related to Mediterranean and West-Asian populations 12,13 , the high frequency of HLA-DR2 and -DQ1 alleles (DRB1*15 and DRB1*16, and DQB1*05 and DQB1*06, respectively) were suggested as genetic protection factor against T1D in the Omani population. 14 However, it remains to be elucidated whether this is true or attributed to low frequency of risk alleles.…”