RFC1 and rheumatoid arthritis: Only three genotype combination patterns occurred for RFC1 80G > A and RFC1−43 T > C, consisting of the 80G/G,−43 T/T genotype, 80G/A,−43 T/C genotype, and 80A/A,−43C/C genotype, respectively and a strong linkage disequilibrium was observed in Japanese RA patients.