Abstract
OBJECTIVE: The efficacy of nucleic acid-based vaccines against SARS-CoV-2 varies across individuals, partly due to genetic factors influencing neutralizing antibody production. In patients with systemic autoimmune diseases (SADs), this response may be further altered by immune dysregulation. METHODS: We conducted a genome-wide association study (GWAS) to identify genetic variants associated with postvaccination anti-SARS-CoV-2 IgG antibody levels and to assess whether these associations differ between patients with SAD and healthy individuals. RESULTS: The study included 165 participants (138 with SADs, 27 healthy controls), all of whom received nucleic acid-based vaccines. Antibody levels targeting the spike protein receptor-binding domain (RBD) and nucleocapsid were measured between 1 and 12 months after vaccination. GWAS results were metaanalyzed with data from a previously published GWAS with 1076 healthy individuals. We identified a novel association near RACGAP1 (rs706785; β(meta) = -0.30, P (meta) = 3.85 × 10(-8)) and replicated a known association at HLA-DRB1 position 71 (β(meta) = -0.23, P (meta) = 1.94 × 10(-11)). No significant interactions were observed between genotype and disease status. CONCLUSION: This study highlights both MHC and non-MHC genetic contributions to SARS-CoV-2 vaccine responses and suggests these effects are consistent across patients with SADs and healthy individuals, supporting standard vaccination strategies for individuals with systemic autoimmune conditions.