Association of the Mannose-Binding Lectin 2 BB Genotype with COVID-19-Related Mortality.

Mannose-binding lectin (MBL) is crucial in first-line immune defenses. There are still many unknown factors regarding the mechanisms causing variability in the clinical course of coronavirus disease 2019 (COVID-19). In Japan, there have been few reports to date regarding the association between MBL and COVID-19. It has been demonstrated that the MBL2 gene B variant at codon 54 (rs1800450) is associated with variabilities in the clinical course of COVID-19. We aimed to investigate how the level of serum MBL and the codon 54 variant of MBL (rs1800450) affect the disease severity of COVID-19. A total of 59 patients from the fourth wave and 49 patients from the fifth wave in Japan were analyzed based on serum MBL levels using ELISA and the genotype of MBL2 codon 54 using PCR reaction. There was no significant association between serum MBL levels and age. MBL2 genotype was independent of age, there was no significant difference in different COVID-19 severities, MBL genotypes, and serum MBL levels. Binary logistic regression analysis to identify predisposing factors for severe COVID-19 symptoms demonstrated that patients with the BB genotype had a higher risk of death from COVID-19. Our results quantitatively demonstrated that the BB genotype might be a factor associated with death from COVID-19.