OBJECTIVES: Identification of the high risk alleles, genotypes and haplotypes of the human leukocyte antigens (HLA) in different populations is beneficial for understanding their roles in type 1 diabetes (T1D) pathogenesis and intervention practices. This study aimed to identify T1D-associated HLA gene alleles in the Omani population.
METHODS: The present case-control study included 73 diabetic seropositive children (mean age 9.08 ± 3.27 years) attending the paediatric clinic at Sultan Qaboos University Hospital in Muscat, Oman, and 110 healthy controls. HLA-A, -B, -C, -DRB1 and -DQB1 genes were genotyped using a sequence-specific primer polymerase chain reaction (SSP-PCR).
RESULTS: Two HLA class I alleles ( B*08, B*58) and three class II alleles ( DQB1*02, DRB1*03 and DRB1*04) were associated with T1D susceptibility, while one class I ( B*51) and three class II ( DQB1*05, DQB1*06 and DRB1*16) alleles were associated with T1D protection. HLA-DRB1*03 and DQB1*02 alleles showed the strongest risk association among all alleles. Six DRB1 residues (E 9, S 11, S 13, Y 30, V 70 and K 71) were significantly associated with T1D susceptibility. Heterozygous genotypes, HLA-DRB1*03/ *04 and DQB1*02/ *03 were significantly associated with T1D susceptibility ( P <0.0001, odds ratio [OR] = 63.21 and P = 0.02, OR = 3.63, respectively). Furthermore, a significant combined action of DRB1*03- DQB1*02 haplotype in T1D risk ( P = 0.000176, OR = 15) and DRB1*16- DQB1*05 haplotype in protection ( P = 0.0312, OR = 0.48) was detected.
CONCLUSION: Known HLA class II gene alleles are associated with T1D in Omani children.