According to the recommendations of domestic and international researchers, because the tumour-onset age in this family is not <25 years, carriers of the MLH1 mutation can be screened for gastric cancer by gastroscopy beginning at 30–35 years old and for CRC by colonoscopy every 1–2 years beginning at 20–25 years old [17, 18]. The gene discussed is MLH1; the disease is gastric cancer.