PERP and gastroesophageal reflux disease: While direct comparison of our own results and these past findings is complicated by less-than-complete overlap of genotyped SNPs between studies, we did not find evidence in support of interactions among BMI, smoking, or GERD symptoms and any assessed variants in previously-implicated genes: GSTM1, GSTT1, VEGF, MGMT, EGF, IL1B, PERP, PIK3CA, TNFRSF1A, CASP7, TP53BP1, BCL2, HIF1AN, PDGRFA, VEGFR1, or MMP1 (Supplemental Table 4).