Genotype frequencies of the CD154 microsatellite in healthy females and those with rheumatoid arthritis. (a) Seventy-nine female patients with rheumatoid arthritis (RA) were compared with 56 healthy females (Pc = 0.483). Genotypes represented fewer than five times are not included. *P = 0.012. (b) The frequency for carriers of two (24/24), one (24/X) or zero (X/X) alleles of 24CAs, where X represents any allele different from 24CAs. One hundred and forty female patients with RA were compared with 80 healthy females (Pc = 0.026). **P = 0.042, ***P = 0.012.