Background: Vitamin D receptor (VDR), influenced by gene polymorphisms like FokI, may affect susceptibility to
infections, including coronavirus disease 2019 (COVID-19). Since studies in children are limited, we aimed to
analyze the correlation between the VDR FokI variant and both the incidence and severity of COVID-19 in
Egyptian children.
Methods: Seventy-seven COVID-19-positive and 107 COVID-19-negative pediatric patients were included. Participants’ serum 25(OH)D levels, inflammatory biomarkers, and demographics were evaluated. Real-time polymerase chain reaction (PCR) was used for genotyping the VDR FokI (rs2228570) polymorphism.
Results: Absolute lymphocyte count (ALC) was significantly lower in COVID-19 patients than in controls, while
interleukin-6 (IL-6), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), procalcitonin, and D-dimer
were significantly higher (all p < 0.001). Vitamin D insufficiency was significantly more common in COVID-19
cases (18.2 % versus 3.7 %, p = 0.002). Male sex, increased tumor necrosis factor-alpha (TNF-α), and CRP were
significantly associated with severe COVID-19 (p = 0.032, 0.029, < 0.001, respectively). The FokI TT genotype in
codominant and recessive models and the T allele in the multiplicative model were significantly correlated with
2.4, 3.0, and 1.8 folds increased COVID-19 risk (p = 0.043, < 0.001, and 0.004, respectively). However, VDR FokI
variants did not significantly associate with severe COVID-19.
Conclusion: The T allele and TT genotype of the FokI variant in the VDR gene increase susceptibility to COVID-19
but not its severity in Egyptian children. Additional research is required to validate the potential role of vitamin
D and its receptor polymorphism in COVID-19