In a multiple logistic regression analysis including IgM-RF and IgG anti-CCP isotype the relative risk for development of RA was not significant for IgM-RF alone, but the odds ratio for IgG anti-CCP isotype was 32.4 (9.0 to 116.9), P < 10-6. The gene discussed is CD40LG; the disease is rheumatoid arthritis.