ABSTRACT
Coronavirus disease 2019 (COVID-19) is an infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but the pathogenesis is unclear. Host genetic background is one of the main factors influencing the patients' susceptibility to several viral infectious diseases. This study aimed to investigate the association between host genetic polymorphisms of two genes, including vitamin D receptor (VDR) and vitamin D binding protein (DBP), and susceptibility to COVID-19 in a sample of the Iranian population. This case-control study enrolled 188 hospitalized COVID-19 patients as the case group and 218 suspected COVID-19 patients with mild signs as the control group. The VDR (rs7975232, rs731236 and rs2228570) and DBP (rs7041) gene single nucleotide polymorphisms (SNPs) were genotyped by Polymerase Chain Reaction Restriction - Fragment Length Polymorphism (PCR-RFLP) method. A significant association between rs2228570 SNP in the VDR gene and the susceptibility of COVID-19 was found between case and control groups. The CT genotype (Heterozygous) of rs2228570 C > T polymorphism showed significant association with a 3.088 fold increased odds of COVID-19 (p < .0001; adjusted OR: 3.088; 95% CI: 1.902-5.012). In addition, a significant association between CC genotype of rs2228570 CT polymorphism and increased odds of COVID-19 in male and female groups (p = .001; adjusted OR: 3.125; 95% CI: 1.630-5.991 and p = .002; adjusted OR: 3.071; 95% CI: 1.485-6.354 respectively) were determined. Our results revealed no significant differences in the frequency of genotype and allele of VDR (rs7975232 and rs731236) and DBP (rs7041) between SARS-CoV-2-infected patients and controls (p > .05). Our results showed that polymorphism of VDR (rs2228570) probably could influence individual susceptibility to COVID-19. The polymorphisms of VDR (rs7975232 and rs731236) and DBP (rs7041) were not associated with SARS-CoV-2 infection susceptibility.