A Chinese family affected by lynch syndrome caused by MLH1 mutation

BMC Med Genet. 2018 Jun 22;19(1):106. doi: 10.1186/s12881-018-0605-x.


Background: Lynch syndrome (LS) is caused by mutations in DNA mismatch repair (MMR) genes, which accounts for 3-5% of colorectal cancer. The risks of several types of cancer are greatly increased among individuals with LS. In this study, 4 members of a Chinese family with a MLH1 pathogenic variant, resulting in colonic carcinoma, was reported.

Case presentation: A 52-year-old colon cancer female was brought to us with a family history of colon cancer. Genetic counseling traced 4 members in her family with colon cancer (mother and 3 siblings including the proband) as well as other cancer types. Next generation sequencing (NGS) with a multiple gene panel including MMR genes showed a germline mutation in MLH1 (c.1852_1854delAAG, p.K618del) in all 3 affected family members and confirmed the diagnosis of Lynch syndrome. In addition, this mutation was also identified in a asymptomatic offspring, who was then recommended to a prophylactic measure against cancer. A personalized health care plan was implemented for monitoring the condition and progression of the affected individuals.

Conclusion: Based on public database searching followed by pedigree verification, p.K618del variant in MLH1 is a pathogenic mutation, which supported the diagnosis of LS. This case highlights the importance of diagnosis and management in patients with hereditary cancer syndromes, particularly for asymptomatic family members.

Keywords: Case report; Colorectal carcinoma; Genetic counseling; Hereditary; Lynch syndrome.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Asian Continental Ancestry Group / genetics*
  • Colorectal Neoplasms / genetics
  • Colorectal Neoplasms, Hereditary Nonpolyposis / genetics*
  • Female
  • Genetic Predisposition to Disease / genetics*
  • Germ-Line Mutation / genetics*
  • Humans
  • Male
  • Middle Aged
  • MutL Protein Homolog 1 / genetics*


  • MLH1 protein, human
  • MutL Protein Homolog 1