Finally, given the effect of MTX therapy on BP levels, a recent study investigated the association between the ATP-binding cassette efflux transporter gene ABCG2 (rs2231142) SNP and BP and arterial stiffness in RA and found that rs2231142 heterozygotes (AC) had significantly lower age-adjusted clinical systolic BP levels when compared to the CC group, however there was no difference in Augmentation Index (AIx) or Pulse Wave Velocity (PWV)98. The gene discussed is ABCG2; the disease is rheumatoid arthritis.