Association of vitamin D receptor Cdx-2 polymorphism with COVID-19: A case-control study

Abstract

Background : Host genetic variability has been suggested as an important explanation for inter-individual differences in COVID-19 susceptibility and severity. Most vitamin D actions in the regulation of immunity are mediated by vitamin D receptors (VDRs). Polymorphisms in the VDR gene have been associated with several health outcomes; however, their effects on COVID-19 still need more clari fi cation. This study aims to investigate the association of the VDR SNP (rs11568820, Cdx-2) with susceptibility and interindividual variability of the severity of COVID-19. Methods : A total of 100 con fi rmed COVID-19 patients and 100 age and sex-matched controls were enrolled in this study between July and September 2021. COVID-19 patients were further subdivided into severe ( n ¼ 50) and nonsevere ( n ¼ 50) cases. All participants were subjected to genotyping of Cdx-2 SNP using the allelic discrimination of the Real-time PCR technique and assay of serum 25(OH)D levels by ELISA. Results : The results showed that the homozygous “ GG ” genotype was signi fi cantly higher in patients vs. controls, whereas the heterozygous “ AG ” genotype was signi fi cantly lower in COVID-19 patients. Thus, the heterozygous “ AG ” genotype is considered the protective genotype. This protection was more signi fi cant among males vs. females ( P ¼ 0.02). However, there were no statistically signi fi cant differences in the genotype distributions of VDR Cdx-2 SNP between severe and nonsevere patients. Moreover, COVID-19 patients with the “ AG ” genotype presented higher 25(OH)D levels than the “ GG ” genotype ( P ¼ 0.02). Conclusions : VDR SNP (rs11568820, Cdx-2) might be a potential risk factor for COVID-19, particularly among male patients.