Objective: We investigated the distribution of HLA-B27 subtypes in patients with ankylosing spondylitis (AS) belonging to two ethnic groups of Colombia.
Material and methods: PCR-SSOs was used to detect the polymorphism in exons 2 and 3 of HLA-B27 in two groups of patients: 39 Mulattos and 20 Mestizos. Fifty-nine of them suffered of ankylosing spondylitis (AS), including two patients with ankylosing spondylitis plus anterior uveitis (AU). Only two 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 B*2702: 12.8% in the Mulattos group; 80% were B*2705 and 20% B*2702 in Mestizos group. The distribution of HLA-B27 subtypes was: 84.74% of patients with AS were B*2705 and 15.26% B*2702.
Conclusions: There was no significant difference in the distribution of HLA-B27 subtypes among the patients 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 controls; 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.