Polymorphism Of Short Tandem Repeat Of Exon 5 Of MHC Class-Ⅰ Chain Related Gene A And Association With Chronic Patients And Hepatitis B Virus Carriers In Hunan Chinese Population

Objective To investigate the genetic polymorphism of microsatellite in theexon 5 of MICA gene(MICA-STR) in HBV carriers,chronic HBV infectious patients and healthy controls of Han population in Hunan Province and analyze the distinction of their genotypes, gene frequency and phenotypic frequency.Methods The microsatellite polymorphism of MICA exon 5 in 108 chronicHBV infectious patients,96 HBV carriers and 142 healthy controls were analyzed using polymerase chain reaction(PCR) and genescanning technique. The genotypes were confirmed by DNA sequencing. .MICA gene deletion was detected byPCR-sequence specific priming(PCR/SSP). The genotypes of MICA exon 5 were determined according to the three detecting results.Results 1. Five alleles of MICA-STR were detected in this study,which are A4,A5,A5.1,A6 and A9.One MICA*Del gene was detected in both HBV carrier group and healthy control group.2. MICA*A5.1/A9 was observed at significantlylower frequency in the chronic HBV patient group than in the healthy control group ( relative risk = 0.378, P = 0.028); MICA* A9 was present at significantly lower frequency in the chronic HBV patient group than in the healthy control group (RR = 0.526, P = 0. 023);Phenotypic frequency of MICA*A9 was significantly lower in chronic HBV patient group than in the healthy control group (RR = 0.431, P = 0. 007).3. MICA*A5.1/A9 was observed at signifieantly lower frequency in the HBV carrier group than in the healthy control group ( relative risk = 0.237, P = 0. 006); Gene frequency of MICA*A9 was signifieantly lower in the HBV carrier group than in the healthy control group (RR=0.535, P=0.032); Phenotypic frequency of MICA*A9 was significantly lower in the HBV carrier group than in the healthy control group (relative risk = 0.464, P = 0. 016).4. The genotypic frequency, allele frequency and phenotypic frequency of MICA exon 5 showed no statistically significant difference between the HBV carrier group and the chronic HBV patient group(P>0.05).Conclusions 1.Five alleles of MICA-STR are detected in Hunan Hanpopulation,which are A4,A5,A5.1,A6 and A9.Among them,the A5 and A5.1 allele are more frequently observed.2.MICA*A5.1/A9 seems to be one of protective genotypes against HBV infection in that it is the first report that its genotypic frequency in HBV carriers and chronic HBV patients is significantly lower than in healthy controls in Hunan Han population.3. It is the first report that the allele frequency and phenotypic frequency of MICA* A9 are significantly lower in HBV carriers and chronic HBV patients than in healthy controls in Hunan Han population,so it is presumed that MICA* A9 is one of protective genes against HBV infection.4. The genotypic frequency, allele frequency and phenotypic frequency show no statistically significant difference between the HBV carriers and the chronic HBV patients in Hunan Han population.