Low variability at the HLA-promoter region in the Brazilian population

Abstract

Little information has been reported regarding the regulatory region of the HLA-gene. Only a proximal segment (300 bp immediately before exon 1) has been described at IMGT/HLA database. We aimed to evaluate the genetic diversity of the promoter region by PCR amplification and DNA sequencing. We observed a pattern of sequencing interruption in the same position in all samples, suggesting the presence of a secondary structure hampering the DNA polymerase sliding during the sequencing process, which was confirmed after bioinformatics analysis. Considering the promoter region evaluated (nucleotide -440 to -1), only three variation sites were found, including one new variation site at position -104, and the concomitant deletions already described at positions -187 and -186. We concluded that the promoter region of the HLA-gene presents few and rare variable sites in this population sample; however, the double-stranded branch formation hampered the evaluation of the distant promoter by conventional sequencing.