We observed higher IBS risk in the dominant model (C/C + C/T vs. T/T, OR = 3.64, 95% CI = (1.19, 11.03)) of HTR3A rs1062613 and the allele model (G vs. A OR = 2.64, 95% CI = (1.14, 5.94)) of OXTR rs2254298. This evidence concerns the gene HTR3A and irritable bowel syndrome.