SI and breast cancer: Of the 8 genes that make up the GRS formula, FEZ1 is a tumor suppressor gene in breast cancer associated with microtubule components, and it can inhibit cancer cell growth by regulating mitosis in breast cancer.[22] The inhibition mechanism in breast cancer may be related to the downregulation of the promoter.[23] The SI gene encodes a protein encoding the sucrase-isomaltase protein that is expressed in the intestinal brush margin, which plays an important role in the carbohydrate absorption function of the intestinal epithelium.