Amribet Meryem^{1, 2,}, Bourhim Noureddine¹, Mkinsi Slaoui Ouafaa³, Belhouari Abderrahmane⁴, Naya Abdellah¹, Fadli Mohamed⁵, Bennani Siham²

The association of HLA-B27 with ankylosing spondylitis accounts for 20 to 50% of the total disease risk. It varies markedly among racial and ethnic populations. The main purpose of the present study is to perform an investigation regarding the distribution of the human leukocyte antigen HLA-B27 and its subtypes in Moroccan healthy controls and in patients with AS and to compare this with other reports from other populations. One hundred twenty-five controls and 116 patients with AS were evaluated in this study. Among patients, three cases were associated to acute anterior uveitis. Typing of the HLA-B27 alleles was performed by microlymphocytotoxicity and polymerase chain reaction amplification with sequence-specific primers. A significant association between ankylosing spondylitis and B27 was identified; HLA-B*27 allele was carried by 46.5% of patients and only one subject from healthy controls was found to be positive (p<0.001, RR= 2.95). Among all positive patients, 64.8% were males and 53.7% belonged to 20-29 and 30–39 age groups. Being male aged 30–39 was significantly associated with B27 positivity. Four HLA- B*27 alleles were observed in this study: B*2705 (44.4%), B*2702 (29.6%), B*2703 (9.2%) and B*2708 (16.7%). The only positive subject from healthy controls carried B*2705 allele. B*2708 subtype was identified in all cases with uveitis. This allele showed a significant association with patients being female. Concluding, HLA-B27 is strongly associated with ankylosing spondylitis in Moroccan population. Our results showed a restricted number of HLA-B27 subtypes with predominance of HLA-B*2705, 02 alleles. The B*2708 allele detected for the first time in North Africa, seems to be associated with ankylosing spondylitis in the studied population.

Ankylosing spondylitis, PCR-SSP, HLA-B27 subtypes, Moroccan population