For example, in the first association analysis, a SNP (rs2476601) in the PTPN22 gene, an excellent candidate gene on chromosome 1 for RA, showed a highly significant (1.784 × 10-12) association with RA but the signal disappeared in the subsequent analysis after correction for stratification effects (p = 4.748 × 10-4). Here, PTPN22 is linked to rheumatoid arthritis.