This article follows a previous study also published in Genes and Immunity last year (http://www.ncbi.nlm.nih.gov/pubmed/24352166) in which researchers studied the worldwide genetic variation in the 3' Untranslated Region (3'UTR)  of HLA-G, a gene of special interest in immune tolerance.

This time, They looked at the 5' Untranslated Regulatory Region (5'URR) of the same gene. We characterized the sequence variation and haplotype structure of the HLA-G 5′URR in worldwide populations to investigate the evolutionary history of the HLA-G promoter and shed some light into the mechanisms that may underlie HLA-G expression control. Our results support a strong molecular signature of balancing selection at HLA-G 5′URR, probably as a result of the competing needs to maintain both a maternal-fetal immune tolerance and an efficient host immune response to invading pathogens during human evolution. An extended analysis of a 300-kb region surrounding HLA-G revealed that this region is not involved in a hitchhiking effect and may be the direct target of selection.

Ref. Art. Gineau et al. 2014. Balancing immunity and tolerance: genetic footprint of natural selection in the transcriptional regulatory region of HLA-G. Genes and Immunity (2014), 1-14. doi: 10.1038/gene.2013.67. Epub 2013 Dec 19.