Functional characterization of MLH1 missense variants identified in Lynch syndrome patients

Hum Mutat. 2012 Dec;33(12):1647-55. doi: 10.1002/humu.22153. Epub 2012 Jul 23.


Germline mutations in the human DNA mismatch repair (MMR) genes MSH2 and MLH1 are associated with the inherited cancer disorder Lynch syndrome (LS), also known as hereditary nonpolyposis colorectal cancer or HNPCC. A proportion of MSH2 and MLH1 mutations found in suspected LS patients give rise to single amino acid substitutions. The functional consequences in regard to pathogenicity of many of these variants are unclear. We have examined the functionality of a panel of MLH1 missense mutations found in LS families, by testing the variant proteins in functional assays, addressing subcellular localization, and protein-protein interaction with the dimer partner PMS2 and the MMR-associated exonuclease 1. We show that a significant proportion of examined variant proteins have functional defects in either subcellular localization or protein-protein interactions, which is suspected to lead to the cancer phenotype observed in patients. Moreover, the obtained results correlate well with reported MMR activity and with in silico analysis for a majority of the variants.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing / chemistry
  • Adaptor Proteins, Signal Transducing / genetics*
  • Adaptor Proteins, Signal Transducing / metabolism
  • Adenosine Triphosphatases / chemistry
  • Animals
  • Colorectal Neoplasms, Hereditary Nonpolyposis / genetics*
  • DNA Repair Enzymes / chemistry
  • DNA-Binding Proteins / chemistry
  • Escherichia coli Proteins / chemistry
  • HeLa Cells
  • Humans
  • Mice
  • Mismatch Repair Endonuclease PMS2
  • Models, Molecular
  • MutL Protein Homolog 1
  • MutL Proteins
  • Mutagenesis, Site-Directed
  • Mutation, Missense*
  • NIH 3T3 Cells
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / genetics*
  • Nuclear Proteins / metabolism
  • Polymorphism, Single Nucleotide
  • Protein Binding
  • Protein Structure, Tertiary
  • Protein Transport
  • Structural Homology, Protein


  • Adaptor Proteins, Signal Transducing
  • DNA-Binding Proteins
  • Escherichia coli Proteins
  • MLH1 protein, human
  • MutL protein, E coli
  • Nuclear Proteins
  • Adenosine Triphosphatases
  • PMS2 protein, human
  • Mismatch Repair Endonuclease PMS2
  • MutL Protein Homolog 1
  • MutL Proteins
  • DNA Repair Enzymes