HLA-G 3'-UTR SNP and 14-bp deletion polymorphisms in Portuguese and Guinea-Bissau populations

In the HLA-G locus, the 3'-untranslated region (3'-UTR) begins in the mid exon 6, and ends in exon 8. The occurrence of a 14-bp deletion within exon 8, the only mutation known until now in the 3'-UTR, has been considered a risk factor for disease and allograft rejection. To describe the polymorphism within this region, direct sequencing analysis was performed on 120 DNA samples from Portugal and Guinea-Bissau. Results indicate that exon 8 is less conserved than the coding exons. Nine single nucleotide polymorphisms and the previously described 14-bp deletion were found within exon 8 of both populations. Molecular diversity was higher in the Guinean samples than in the Portuguese; however, little differentiation was found among the populations, suggesting that local selection on exon 8 sequence variation is absent. The screening for sequence motifs suggests that polymorphism on this region may be involved in HLA-G post-transcriptional regulation and, therefore, in phenotype variation.