Results of Expedicion Humana. II. Analysis of HLA class II alleles in three African American populations from Colombia using the PCR/SSOP: identification of a novel DQB1*02 (*0203) allele.

Abstract

PCR/SSOP typing methods were used to analyze the HLA Class II DRB1, DQA1, DQB1 and DPB1 loci of samples from three African American populations of Colombia. Forty samples from the Cauca (Pacific), and twenty samples each from the Choco (North Pacific Coast) and the Providencia (Caribbean island) populations, were collected and the Class II loci analyzed under the auspices of the Expedicion Humana. Despite the limited number of samples analyzed, the African Colombian populations exhibit a very high degree of class II polymorphism. A great diversity of DRB1 alleles was found, with representatives from all serological classes, including 19 DRB1 alleles in the Providencia, 16 in the Cauca and 14 in the Choco groups. In addition, a novel DQB1*02 allele (*0203) was found in two individuals from the Cauca population of the Pacific Coast. The sequence of the DQB1*0203 allele, associated with DR3, differs from DQB1*0201 by only one nucleotide substitution (C-->A) in the second position of codon 57, resulting in an Ala to Asp change. The addition of DQB1*0203 brings the total number of DQB1 alleles identified to date to 26. HLA class II diversity is much greater in these African Colombian populations than that seen in nearby Amerindian populations. Analysis of regional Colombian African American HLA population genetics is discussed with respect to the Colombian Amerindian HLA genetics described in an accompanying paper.