The association between vitamin D receptor polymorphism and phases of chronic hepatitis B infection in HBV carriers in Thailand

Vitamin D receptor (VDR) polymorphism partly regulates the immune system and is associated with hepatic flare in chronic Hepatitis B virus infection (HBV). Our study identified the association between two distinct phases, VDR polymorphisms and HBV inactive carrier (IC) and chronic hepatitis (CH). Chronic HBV patients were enrolled from February to August 2020. An HBV viral load (VL) < 2,000 IU/ml twice for 6 months apart, with no prior history of HBV treatment, defined the IC phase. Six common polymorphisms in the VDR gene, including CdX-2, GATA, FokI, Bsml, ApaI, and TaqI, were studied using real-time PCR. The different outcomes in allele, genotype, and haplotype frequencies in between groups and linkage disequilibrium (LD) mapping were analyzed. Among 324 enrolled patients, there were 163 patients in IC and 161 patients in CH phases. The mean vitamin D levels were not statistically different between groups. The proportion of allele frequencies of CdX-2 in IC and CH was 53.7% and 62.7% for G allele, and 46.3% and 37.3% for A allele (p 0.019). The proportion of GG genotype of CdX-2 was less frequently found in patients with IC compared to that in patients with CH (27% vs 41%, p 0.028). By multivariate analysis, CdX-2 G/A genotypes were independently associated with IC, with adjusted odd ratio (OR) 1.83 (1.10–3.04), p 0.019. The LD mapping of single nucleotide polymorphisms (SNP) revealed high LD scores in Bsml/ApaI/TaqI (BAT) haplotype in both groups while, CdX-2/GATA and GATA/FokI demonstrated high LD score only in CH group. CdX-2 G/A genotypes were independently associated with IC status in Thai patients with chronic HBV infection. The difference in LD of the CdX-2/GATA and GATA/FokI haplotypes in between groups may represent a non-random selection resulting in the variation of immune control

Allele and genotype frequencies of six VDR SNPs including <i>CdX-2</i>, <i>GATA</i>, <i>Fok</i>I, <i>Bsm</i>l, <i>Apa</i>I and <i>Taq</i>I in patients with HBeAg positive (N 62) and negative (N 254).

(DOCX)</p

Haplotype frequencies of VDR SNPs in HBV inactive carrier and chronic hepatitis phases.

Haplotype frequencies of VDR SNPs in HBV inactive carrier and chronic hepatitis phases.</p

Allele and genotype frequencies of six VDR SNPs, including <i>CdX-2</i>, <i>GATA</i>, <i>Fok</i>I, <i>Bsm</i>l, <i>Apa</i>I, and <i>Taq</i>I in healthy controls.

(DOCX)</p

Baseline characteristics of patients with HBV inactive carrier (IC) and chronic hepatitis (CH) phases.

Baseline characteristics of patients with HBV inactive carrier (IC) and chronic hepatitis (CH) phases.</p

Haplotype frequencies of six VDR SNPs including <i>CdX-2</i>, <i>GATA</i>, <i>Fok</i>I, <i>Bsm</i>l, <i>Apa</i>I and <i>Taq</i>I in patients with HBeAg positive (N 62) and negative (N 254).

(DOCX)</p

Univariate and multivariate regression analysis of factors associated with HBV inactive carrier (IC) phase.

Univariate and multivariate regression analysis of factors associated with HBV inactive carrier (IC) phase.</p

Genomic organization and linkage disequilibrium (LD) mapping of six SNPs of vitamin D receptor (<i>VDR</i>) gene.

Patients with HBV inactive carrier (IC), chronic hepatitis (CH) phases and the general population.</p

Vitamin D levels according to <i>CdX-2</i> genotypes in HBV inactive carrier and chronic hepatitis phases.

Vitamin D levels according to CdX-2 genotypes in HBV inactive carrier and chronic hepatitis phases.</p

Allele and genotype frequencies of VDR SNPs in HBV inactive carrier and chronic hepatitis phases.

Allele and genotype frequencies of VDR SNPs in HBV inactive carrier and chronic hepatitis phases.</p