New evidence for balancing selection at the HLA-G locus in South Amerindians

hla-g is a non-classical hla (human leukocyte antigen) molecule characterized by limited tissue distribution under normal physiological conditions and low variability at both dna and protein levels. several studies suggest that hla-g could play a role, as an immunoregulatory molecule, in situations as diverse as transplantation, cancer, viral infections and inflammatory diseases. a total of 237 individuals from 21 south american tribes speaking nine different linguistic families were studied in relation to the 14 bp insertion/deletion polymorphism at the hla-g gene. a consistent (seven in nine) excess of heterozygosity in samples classified by language was obtained. our data supply evidences for balancing selection acting at the hla-g 14 bp indel region. enhanced fetal survival in a pathogen-rich environment may account for these findings.