Systematic analysis of hMSH2 and hMLH1 in young colon cancer patients and controls.
Germ-line mutations in DNA mismatch-repair genes impart a markedly elevated cancer risk, often presenting as autosomal dominant hereditary nonpolyposis colorectal cancer (HNPCC). However, there are no pathognomonic features of HNPCC, not all gene carriers have a family history of the disease, and families fulfilling the Amsterdam criteria are relatively uncommon. Genetic testing of probands with early-onset colorectal cancer, irrespective of family history, is one approach that would allow predictive genetic testing of at-risk relatives. We cloned and sequenced hMSH2 and hMLH1 introns, to optimize genomic sequencing. We then systematically analyzed the entire hMSH2 and hMLH1 genes, by genomic sequencing and in vitro synthesized-protein-truncation assay (IVSP), in 50 colorectal cancer patients <30 years of age at diagnosis. To determine polymorphic variants, 26 anonymous donors also were sequenced. All subjects analyzed had at least 1 of 37 different polymorphic or pathogenic variants. IVSP complemented genomic sequencing, by detection of mutations not identified by genomic analysis. Fourteen cancer patients (28%) had pathogenic mutations, and a number of other variants also may have had a pathogenic significance that remains to be elucidated. Tumor replication-error status was useful in targeting sequencing efforts for this cohort of young patients: sensitivity was 86%, specificity 73%, and positive and negative predictive values 63% and 90%, respectively. These data indicate that an appreciable proportion of young colon cancer probands carry a germ-line mutation in a DNA mismatch-repair gene.
Department of Surgery, University of Edinburgh, Western General Hospital, Edinburgh, United Kingdom.
S M
SM
Farrington
J
J
Lin-Goerke
J
J
Ling
Y
Y
Wang
J D
JD
Burczak
D J
DJ
Robbins
M G
MG
Dunlop
D048868:Adaptor Proteins, Signal Transducing; D000328:Adult; D000367:Age Factors; D002352:Carrier Proteins; D003110:Colonic Neoplasms / Q000235:genetics*; D015179:Colorectal Neoplasms / Q000235:genetics*; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000235:genetics; D004260:DNA Repair / Q000235:genetics; D004268:DNA-Binding Proteins; D005091:Exons; D005260:Female; D006801:Humans; D008297:Male; D018895:Microsatellite Repeats; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics*; D009687:Nuclear Proteins; D017354:Point Mutation; D016133:Polymerase Chain Reaction; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D012307:Risk Factors; D017384:Sequence Deletion
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C501486:MLH1 protein, human; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; C497172:MSH2 protein, human; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein