HLA-G UTR haplotype conservation in the Malian population: association with soluble HLA-G

PLoS One. 2013 Dec 23;8(12):e82517. doi: 10.1371/journal.pone.0082517. eCollection 2013.

Abstract

The HLA-G molecule plays an important role in immunomodulation. In a previous study carried out on a southern French population our team showed that HLA-G haplotypes, defined by SNPs in the coding region and specific SNPs located in 5'URR and 3'UTR regulatory regions, are associated with differential soluble HLA-G expression (sHLA-G). Furthermore, the structure of these HLA-G haplotypes appears to be conserved in geographically distant populations. The aim of our study is to confirm these expectations in a sub-Saharan African population and to explore additional factors, such as HLA-A alleles, that might influence sHLA-G expression. DNA and plasma samples were collected from 229 Malians; HLA-G and HLA-A genotyping were respectively performed by the Snap Shot® method and by Luminex™ technology. sHLA-G dosage was performed using an ELISA kit. HLA-G and HLA-A allelic and haplotypic frequencies were estimated using an EM algorithm from the Gene[Rate] program. Associations between genetic and non genetic parameters with sHLA-G were performed using a non-parametric test with GRAPH PAD Prism 5. Our results reveal a good conservation of the HLA-G UTR haplotype structure in populations with different origins and demographic histories. These UTR haplotypes appear to be involved in different sHLA-G expression patterns. Specifically, the UTR-2 haplotype was associated with low sHLA-G levels, displaying a dominant negative effect. Furthermore, an allelic effect of both HLA-G and HLA-A, as well as non genetic parameters, such as age and gender possibly linked to osteogenesis and sexual hormones, also seem to be involved in the modulation of sHLA-G. These data suggest that further investigation in larger cohorts and in populations from various ethnical backgrounds is necessary not only to detect new functional polymorphism in HLA-G regulatory regions, but also to reveal the extent of biological phenomena that influence sHLA-G secretion and this might therefore have an impact on transplantation practice.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3' Untranslated Regions / genetics*
  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Alleles
  • Child
  • Child, Preschool
  • Conserved Sequence / genetics*
  • Female
  • Gene Frequency
  • Genetic Loci
  • HLA-A Antigens / genetics
  • HLA-G Antigens / genetics*
  • Haplotypes / genetics*
  • Humans
  • Linkage Disequilibrium / genetics
  • Male
  • Mali
  • Middle Aged
  • Polymorphism, Single Nucleotide / genetics
  • Solubility
  • Young Adult

Substances

  • 3' Untranslated Regions
  • HLA-A Antigens
  • HLA-G Antigens

Grants and funding

This study was funded by the Etablissement Français du Sang (EFS) Alpes Méditerranée, Marseilles, France and by the Malaria Research and Training Center, Bamako, Mali. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.