A null mutation in HLA-G is not associated with preeclampsia or intrauterine growth retardation

Modulation of the expression of genes of the major histocompatibility complex (MHC) in tissues at the maternal-fetal interface almost certainly plays a role in successful development of the semi-allogeneic fetus. While expression of the classical class I genes (HLA-A, B, C) is low to non-existent at this site, the non-classical molecule, HLA-G, is expressed uniquely in fetal cells at the maternal-fetal interface. The recent demonstration that homozygotes for a deletion mutation in exon 3 (1597DeltaC) of HLA-G do not express the full-length HLA-G1 isoforms indicates a potential reduction in expression of this isoform in heterozygotes. If the full-length isoform of HLA-G (i.e. HLA-G1) contributes to proper invasion of maternal spiral arteries by extravillous cytotrophoblast, then 1597DeltaC heterozygotes could be at increased risk for disorders of trophoblast invasion. Two populations, infants with intrauterine growth retardation (IUGR) and infants of preeclamptic (PE) mothers, were genotyped for the 1597DeltaC polymorphism. The frequency of 1597DeltaC in these samples was not significantly different from healthy controls, suggesting that heterozygotes for this deletion mutation are not at significantly increased risk for PE or IUGR (P = 0.727 and 0.803, respectively).