In COMT rs4680 gene dosage models of change in the pain frequency and pain severity components of the IBS-SSS from baseline to 6-weeks, increasing number of met alleles was associated with a significantly greater reduction in IBS pain severity [beta(SE), −5.9 (2.6), P = 0.028], but not frequency [beta(SE), −0.52(0.40), P = 0.198] across all participants combined. The gene discussed is COMT; the disease is irritable bowel syndrome.