The distributions of the RFC1 80G > A allele in African [4, 11] in healthy adults and Caucasian [24, 34–36] in RA patients, RFC1−43 T > C allele in Caucasian [4] in healthy adults, ABCB1 3435 C > T allele in Caucasian [4] in healthy adults, and ABCC2 IVS23 + 56 T > C allele in Asian [4] and African [4] healthy adults were not in agreement with Hardy-Weinberg equilibrium. Here, ABCC2 is linked to rheumatoid arthritis.