The Association of Human Leukocyte Antigen Genotyping Among Sudanese Patients With Rheumatoid Arthritis: Reference to Ethnicity.

Abstract

Human leukocyte antigens (HLA) account for up to one-half of the total genetic contribution to rheumatoid arthritis (RA) risk. The study investigated the association of HLA class II genotyping with RA susceptibility in Sudanese ethnic groups. The DRB1 and DQB1 alleles and haplotypes were determined in 122 RA patients (i.e., Gaalia = 54, Johayna = 24, Baggara = 17, Nile Nubian = 12, and others = 15) and 120 healthy controls ofethnic groups (i.e., Gaalia = 44, Johayna = 11, Baggara = 15, Nile Nubian = 9, and others = 21) using a polymerase chain reaction with sequence-specific primers method. Susceptibility to RA was associated with a high frequency of DRB1*04(P = 0.04), DRB1*10(P = 0.04), and DQB1*03(P= 2.2 x 10-8/Pc = 6.6 x 10-8) between study ethnic groups, while protective effects were shown with DRB1*07(P= 0.01), DQB1*02(P= 0.02), andDQB1*06(P= 2.2 x 10-6/Pc= 6.6 x 10-6), with an inconsistent frequency between study ethnic groups.The HLA haplotypes that were high in frequency among RA ethnic groups and showed susceptibility associations were DRB1*03-DQB1*03,DRB1*04-DQB1*03,DRB1*08-DQB1*03, DRB1*13-DQB1*02,and DRB1*13-DQB1*03 (P= 0.00003/Pc = 0.0003,P= 0.0001/Pc= 0.0001,P= 0.03, P= 0.004/Pc= 0.03, and P= 3.79x10-8/Pc= 3.3x10-9,respectively). On the contrary, DRB1*03-DQB1*02,DRB1*07-DQB1*02, andDRB1*13-DQB1*06 were lower in frequency in the ethnic groups with RA and may confer protection (P= 0.004/Pc= 0.032,P= 0.002/Pc= 0.02, and P= 0.01, respectively). Our findings indicate an association between HLA-DRB1 and DQB1 genotypes and the susceptibility to RA in the Sudanese population, with a moderate frequency between our ethnic groups.