Human Leukocyte Antigen-G Gene Polymorphism in Peninsular Malaysia: A Preliminary Report.

Abstract

Introduction: Expression of the nonclassical human leukocyte antigen (HLA)-G gene is upregulated in placenta during pregnancy. In other cells, HLA-G is upregulated during parasitic infections and allergic reactions. Polymorphism at the HLA-G gene locus has been reported for many populations, but so far not for any ethnic groups in Malaysia. In this survey, we screened for genetic variation in HLA-G genes from representative Malay, Chinese, and Indian individuals living in Peninsular Malaysia. Materials and Methods: Blood samples were obtained with informed consent, and ethnicity classes were assigned based on self-declared pedigree information. Exons 2, 3, and 4 of the HLA-G gene were amplified by polymerase chain reaction and subjected to Sanger sequencing. Results: The most common genotype in Malays and Indians was found to be HLA-G*01:01:01:01/01:01:01:01 with frequencies of 0.206 and 0.167, respectively, whereas the HLA-G*01:01:03:01/01:01:01:01 genotype was the one most frequently observed in Chinese (0.221). Based on this study, HLA-G*01:01:01:01 (0.427-0.448) is the most frequent HLA-G allele in the all three ethnic groups. In contrast, HLA-G*01:01:02:01 (0.186) was observed as the second most frequent HLA-G allele in Malays and HLA-G*01:04:01 in Chinese and Indians, (0.188-0.198, respectively). Several minor HLA-G alleles were detected at low frequency in Malays, Chinese, or Indians (HLA-G*01:01:05, 01:01:09, 01:04:02, and 01:04:03). These have only rarely, if ever, been reported in other population groups. Subsequent statistical analysis including using principal coordinate data mapping showed the Malays, Chinese, and Indians are distinct but quite closely related to one another as compared with other population groups from across Europe and Africa. Conclusion: The HLA-G population data collected in this study showed that the ancestrally unrelated Malays, Chinese, and Indians are genetically distinct. This new database provides a foundation for further studies to capture HLA-G allelic diversity in uncharacterized populations of Malaysia and for future attempts to identify their roles in disease resistance and susceptibility.