MBL2 encodes mannose-binding lectin (MBL), a calcium-dependent pattern recognition receptor that initiates the lectin complement pathway for innate immunity 1. MBL recognizes mannose moieties on pathogen surfaces and activates MASP1 serine protease, triggering proteolytic cascade leading to pathogen phagocytosis and complement activation 1. Against SARS-CoV-2, MBL activation inhibits viral infection and reduces inflammatory response 2. Clinically, MBL2 polymorphisms significantly influence susceptibility to multiple infections. Exon 1 variants associate with increased high-risk HPV infection and cervical cancer risk in Caucasians 3, while promoter variants (c.-290C>G) increase meningitis susceptibility 4. MBL2 polymorphisms modulate HIV-1 infection susceptibility and treatment response, with protective and risk-conferring alleles identified 56. Low/null-MBL expression haplotypes increase posttransplant bacterial, fungal, and CMV infections in organ recipients 7. In tuberculosis, rs1800451 homozygous variants show protective effects 8. Notably, MBL2 polymorphisms show no consistent association with asthma risk 9 or rheumatoid arthritis 10, suggesting disease-specific genetic effects.