Lynch syndrome (LS) is an autosomal dominant inherited disease caused by germline mutations in DNA mismatch repair (MMR) genes, including MLH1, MSH2, MSH6, and PMS2, which predisposes patients to various malignant neoplasms. Previous studies showed that MLH1, MSH2, MSH6, and PMS2 mutation in LS were associated with an elevated risk of colorectal, gastric, endometria, ovarian, and other cancers among family members. Patients of these kinds of cancers had high incidence of synchronous and metasynchronus. We describe the case of a 34-year-old female patient with 50 days of sudden dizziness and left limb weakness, whose head CT scan showed large infarction in the right frontal temporal parietal lobe and basal ganglia area. Imaging examinations and pathological biopsy indicated high-grade serous carcinoma (HGSC) IIIA1 of the right ovary. In addition, a novel frame-shift mutation in the MLH1 gene (c.1621dupG, p.A541Gfs*16) was found in the genetic panel sequence. It may render declining of MLH1 protein and also associate with the patient’s progressive clinical manifestations of multiple systems. Therefore, the timely use of prenatal diagnosis to prevent unnecessary new cases of this severe genetic disease is available.

Lynch综合征（LS）是由DNA错配修复（MMR）基因的种系突变引起的常染色体显性遗传疾病，包括MLH1，MSH2，MSH6和PMS2，这使患者容易患上各种恶性肿瘤。先前的研究表明，LS中的MLH1，MSH2，MSH6和PMS2突变与家庭成员中大肠癌，胃癌，子宫内膜癌，卵巢癌和其他癌症的风险升高相关。这类癌症患者的同步和后同步发生率很高。我们描述了一个患有50天突然头晕和左肢无力的34岁女性患者的情况，该患者的头部CT扫描显示右额颞叶顶叶和基底神经节区域有大面积梗塞。影像学检查和病理活检显示右卵巢高度浆液性癌（HGSC）IIIA1。此外，在基因组序列中发现了MLH1基因的一个新的移码突变（c.1621dupG，p.A541Gfs * 16）。它可能导致MLH1蛋白下降，并且还与患者多个系统的进行性临床表现相关。因此，可以及时使用产前诊断来预防这种严重遗传病的不必要的新病例。