Rheumatoid arthritis (RA) is an autoimmune multifactorial disease which has a great socio-economic impact in Morocco. The association of HLA genes with RA was studied in various ethnic groups but not in the Moroccan population. Our study focused on evaluating the distribution of class I and class II HLA genes among Moroccan patients presenting early signs of RA.
Forty nine patients diagnosed with early RA were compared to a group of healthy controls matched by age, sex, and ethnic origin. Among the patient group, 34 were seropositive (presence of the rheumatoid factor). HLA typing of the patients and the controls was performed using microlymphocytotoxicity for class I (A and B) and PCR-SSP for class II (DR and DQ).
We found a significant increase of the frequency of the HLA-A24 antigen (p=0.03), the DRB1*04 (p=0.004) and DQB1*03 (p=0.03) alleles and a significant decrease of the DRB1*07 allele (p=0.03) in seropositive patients. The analysis of the frequency of the DRB1*01, DRB1*10, and DRB1*14 alleles did not show any difference between the RA patients and the controls. The frequency of DR4-DQ2 and DR4-DQ4 haplotypes was increased in the patients compared to the controls while that of DR7-DQ2 and DR13-DQ6 was decreased.
Our study suggests that DRB1*04 predisposes to RA while DRB1*07 seems protective for the Moroccan patients population. In addition we show the influence of some haplotypes DR-DQ in the susceptibility and protection against the disease.