Vitamin D deficiency and vitamin D receptor FokI polymorphism as risk factors for COVID-19: A case-controlled study

Abstract

Background: Low Vitamin D (Vit D) levels are prevalent globally and suggest the relevance of Vit D in respiratory infections as its low levels have been related to an elevated risk of viral upper respiratory tract infections & pneumonia.Objectives: To assess any role of VDR FokI polymorphism and vitamin D deficiency as predisposing factors for COVID-19.Methods: We enrolled 180 COVID-19 cases and 200 matched controls. RT-PCR was utilized to confirm all subjects' SARS-CoV-2 positivity and genotypes of the VDR Fok1 polymorphism.Results: Low Vit D levels were found in 94 (52%) cases; of them, 20 (11%) were insufficient and 74 (41%) were deficient. Vit D insufficiency was related to a 2.6-fold increase in COVID-19 incidence (P 0.001). The frequency of the FokI FF genotype was significantly higher in cases compared to controls (P <0.001). The logistic regression's significant OR (CI) values of VDR Fok I genotype (FF vs. Ff + ff) OR value was 4.5 with P value <0.001. Conclusion: Vit D deficiency was related to a 2.1-fold increase in COVID-19 risk (P = 0.002). The F allele and VDR FokI FF genotype were independent risk factors for COVID-19 (P = 0.003, < 0.001).