CYP2C9 and myalgic encephalomeyelitis/chronic fatigue syndrome: These differences allowed us to propose the presence of the genetic variant CYP2C9*3 as a candidate marker of disease state with specific reference to SRI, as also confirmed by calculation of disease risk by Odds Ratio (OR), that was increased in a range from 7- to 26-fold for MCS, SMCS, and FM/CFS conditions, respectively.