HLA-B27 subtypes in patients with ankylosing spondylitis (As) in Colombia

Objective. We investigated the distribution of HLA-B27 subtypes in patients with ankylosing spondylitis (AS) belonging to two ethnic groups of Colombi a. Material and methods. PCR-SSO5 was used to detect the polymorphism in ex ons 2 and 3 of HLA-B27 in two groups of patients: 39 Mulattos and 20 Mestiz os. Fifty-nine of them suffered of ankylosing spondylitis (AS), including t wo patients with ankylosing spondylitis plus anterior uveitis (AU). Only tw o out of eight HLA-B27 subtypes studied (B*2701-B*2708) were found. Results . The distribution of these alleles in the whole population was: B*2705: 87 .1% and 8*2702: 12.8% in the Mulattos group; 80% were B*2705 and 20% 8*2702 in Mestizos group. The distribution of HLA-B27 subtypes was: 84.74% of pat ients with AS were B*2705 and 15.26% B*2702. Conclusions. There was no sign ificant difference in the distribution of HLA-B27 subtypes among the patien ts ethnic groups studied. Other authors have shown that B*2705, B*2702 and B*2704, the more frequent subtypes, are equally associated to the disease. Although population studies need to be done to analyze the distribution of subtypes between patients and controls, the low frequency of HLA-B27 within the normal population does not permit to do a representative number of con trols; our results suggest that HLA-B*2705 and HLA-B*2702 are the subtypes more frequently associated with AS in patients from the two more prevalent patients ethnic groups in Colombia.