Objective: To explore the relationship between HBV infection and the genotypes and allele frequencies of CIITA G-944C gene polymorphism in three minority populations (Jinuo, Dai and Aini population) in Xishuangbanna district, Yunnan province.
Methods: Polymerase chain reaction and sequencing method were used to study the genotypes and allele frequencies distributions of CIITA G-944C gene polymorphism in those three populations. Relationship between the genotypes distribution and HBV infection results were also analyzed.
Results: The rates on HBV infection and HBsAg carrier status in Aini minority population were 89.2% and 16.3%, which were significantly higher than in Jinuo (27.9% and 3.9%, χ(2) = 135.196 and 10.361, P = 0.000 and 0.001) and Dai population (44.9% and 6.6%, χ(2) = 96.783 and 8.748, P = 0.000 and 0.003) while among Aini population it was significantly different with the other two minority populations. The CC genotype and C allele frequencies were more distributed in Aini population than in the other two minority populations. In contrast, the GG genotype and G allele frequencies were lower than the other two minority populations, with χ(2) rates between Aini and Jinuo population were 11.841 and 12.208 and the P as 0.003 and 0.000 respectively while the χ(2) rates between Aini and Dai population were 23.902 and 20.220 with P value as 0.000 and 0.000. The genotypes frequencies of CIITA G-944C was significantly different in the infected individuals (IF) group and health control (HC) group in Jinuo population (χ(2) = 6.150 and 4.911, P = 0.046 and 0.027). When compared with HBsAg(+) group and HBsAg(-) group, the genotypes and allele frequencies were different in Aini population and the total three minority populations (χ(2) rates in Jinuo minority were 8.650 and 5.034 with P values as 0.013 and 0.025). However, the χ(2) rates in the whole population were 13.047 and 9.416 with P values as 0.001 and 0.002, respectively. The distribution of CC genotype and C allele gene in HBsAg(+) group was increasing. Data from non-condition logistic regression analysis and adjusting for confounding factors, the HBsAg(+) group had a significantly increase of HBsAg(-) group under the C allele Recessive Model (P = 0.000; OR = 2.964; 95%CI: 1.609 - 5.460).
Conclusion: The genotypes and allele frequencies distribution of CIITA G-944C were different in the three ethnic populations. Polymorphism of this gene was closely associated with HBsAg carrier. The CC genotype patients were more easily to become HBsAg carrier.