Lynch syndrome (LS), which is the most common hereditary colorectal cancer, accounts for about 3% of all colorectal cancers. However, due to its various clinical manifestations, it is difficult to be diagnosed. The diagnosis of LS requires comprehensive application of various screening criteria (such as the Amsterdam criteria, Bethesda criteria), predictive models, risk factors, immunohistochemistry test of mismatch repair (MMR) protein, microsatellite instability (MSI) detection, MLH1 methylation detection, BRAF gene mutation detection, germline gene mutation detection, and so on. LS can be diagnosed only after the identification of pathogenic germline mutation of MMR gene. The first-degree and second-degree relatives of LS patients are recommended to be tested for the identified mutant gene. For LS patients and gene mutation carriers, LS associated cancer can be detected early or even prevented by monitoring and preventive surgery. Reproductive techniques can be used to prevent this disease from being passed down to the next generation.
林奇综合征约占所有结直肠癌的3%，是最常见的遗传性结直肠癌，但是由于其临床表现多样，诊断困难。其筛查需要综合应用阿姆斯特丹（Amsterdam）、贝塞斯达（Bethesda）等各种筛查标准、预测模型、警示表现、免疫组织化学检测错配修复缺陷（dMMR）、微卫星不稳定性（MSI）、MLH1甲基化、BRAF基因突变和胚系基因突变检测等各种方法。只有找到了错配修复基因的致病性胚系突变后，才能确诊为林奇综合征。建议患者的一级亲属和二级亲属均检测该突变基因。通过对患者和基因突变携带者进行随访监测和预防性手术，可以早期发现、甚至预防癌症，还可以通过生殖医学的手段，阻止该疾病遗传给下一代。.
Keywords: Deficient mismatch repair (dMMR); Hereditary colorectal cancer; Lynch syndrome; Microsatellite instability (MSI); Screening criteria.