Null allele frequencies at HLA-G locus in Iranian healthy subjects

HLA-G gene contains 15 alleles including a null allele, HLA-G*0105N. Previous studies have shown that HLA-G*0105N does not encode the complete HLA-G1 or HLA-G5 isoforms but encodes a functional HLA-G protein with the ability to inhibit NK cell cytolysis. Thus, although the biological functions of HLA-G1 and HLA-G5 proteins are abrogated, other isoforms such as HLA-G2 can replace their roles. Studies on the null allele of HLA-G gene could be useful in understanding the genetic variants of HLA-G alleles in ethnic groups.

The goal of this research was to determine the frequency of HLA-G*0105N null allele in Iranian healthy subjects.

The frequency of HLA-G*0105N null allele was evaluated in Iranian healthy subjects by PCR-RFLP method. Genomic DNA was isolated from the whole blood of 100 randomly selected, healthy, unrelated Iranian individuals using salting-out technique followed by PCR amplification of the exon 3 of HLA-G gene. PCR products were digested with PpUM-1 and the resulted fragments were analyzed using gel electrophoresis.

In this study the restriction enzyme digestion confirmed homozygous HLA-G*0105N null allele for 9 % of the population. Furthermore obtained results indicated that the total frequency of HLA-G*0105N null allele was 20 % in the studied population of Iran.

The final data analysis showed that the total frequency of this allele in Iranian people was higher than other ethnic groups that have been studied so far.