C3 and systemic lupus erythematosus: In Online Mendelian Inheritance in Man (OMIM), the NCF1 gene is associated with chronic granulomatous disease, the CFTR gene is associated with cystic fibrosis and hereditary pancreatitis, the BRCA2 gene is associated with male breast cancer, medulloblastoma, prostate cancer, and pancreatic cancer, the PTPN22 gene is associated with SLE, diabetes mellitus type 1, and rheumatoid arthritis susceptibility, the C3 gene is associated with age-related macular degeneration and C3 deficiency, and the HLA-DRB1 gene is associated with multiple sclerosis and sarcoidosis susceptibility (Table 2).