HLA-G Polymorphisms and Allele Frequencies in Caucasians

• Published in: Human immunology 1998-05, Vol.59 (5), p.302-312
• Main Authors: van der Ven, K., Skrablin, S., Engels, G., Krebs, D.
• Format: Article
• Language: English
• Subjects: Adult; Alleles; Child; European Continental Ancestry Group - genetics; Female; Histocompatibility Antigens Class I - genetics; HLA Antigens - genetics; HLA-G Antigens; Humans; Mutation; Polymerase Chain Reaction; Polymorphism, Genetic - genetics; Sequence Alignment
• ISSN: 0198-8859; 1879-1166
• DOI: 10.1016/S0198-8859(98)00021-4

HLA-G, a nonclassical class I MHC molecule, is uniquely expressed on extravillous cytotrophoblasts of the maternal-fetal interface and is suggested to be essential for establishment of maternal-fetal immune tolerance. Although the level of polymorphism in HLA-G has originally been considered low, number, nature and site of polymorphisms seem to vary between different ethnic populations. We investigated HLA-G polymorphisms in a population of German and Croatian origin by SSCP-analysis and direct sequencing as well as RFLP analysis for presence of the 1597delC mutation. HLA-A alleles associated with the different HLA-G alleles were determined by SSP PCR-typing. In Caucasians, HLA-G exhibits a low degree of polymorphism on the amino-acid level and only slightly higher variability on the nucleotide level. In 264 independent chromosomes, 4 HLA-G alleles on the level of amino acid polymorphisms and an additional 6 variations of nucleotide sequences could be identified. The null-allele G∗0105N was present at an allele frequency of 2.3%, which is higher than initially suggested for Caucasians but lower than in Hispanics and African-Americans. Furthermore, some HLA-G alleles exhibit strong linkage disequilibrium with HLA-A.