Mean age of tumor onset in hereditary nonpolyposis colorectal cancer (HNPCC) families correlates with the presence of mutations in DNA mismatch repair genes.
Fourteen Italian families affected with hereditary nonpolyposis colorectal cancer (HNPCC) were screened for germline mutations at three DNA mismatch repair (MMR) genes, MSH2, MLHI, and GTBP, by using a combination of different methods that included an in vitro synthesized protein assay, single-strand conformation polymorphism analysis, and direct sequencing. DNA alterations were observed in six instances, including a single base deletion in MSH2 exon 14, an A-to-G transition in the splice donor site of MLHI exon 6, and two missense mutations in MLHI exons 5 and 9. A previously reported common mutation affecting the splice donor site of MSH2 exon 5 was identified in two families. No mutations were detected in the GTBP gene. In total, eight of 16 Italian HNPCC families (50%), including two previously reported kindreds, were found to carry a mutation in MMR genes. We compared the mean age of colorectal cancer onset in the index cases (three patients for each family) between the two groups of kindreds, those with identified mutation vs. those without, and found that the first had a significantly lower value (43.0 vs. 53.7 years, P = 0.014). This finding suggests that HNPCC families with a more advanced age of tumor onset are less likely to be associated with known MMR genes.
Pensotti
V
V
Division of Experimental Oncology A, Istituto Nazionale Tumori, Milano, Italy.
Radice
P
P
Presciuttini
S
S
Calistri
D
D
Gazzoli
I
I
Grimalt Perez
A
A
Mondini
P
P
Buonsanti
G
G
Sala
P
P
Rossetti
C
C
Ranzani
G N
GN
Bertario
L
L
Pierotti
M A
MA
D048868:Adaptor Proteins, Signal Transducing; D000328:Adult; D017668:Age of Onset; D000368:Aged; D002352:Carrier Proteins; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000453:epidemiology / Q000235:genetics*; D004252:DNA Mutational Analysis; D004260:DNA Repair / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D005260:Female; D018095:Germ-Line Mutation; D006801:Humans; D008297:Male; D008875:Middle Aged; D000070957:MutL Protein Homolog 1; D051718:MutS Homolog 2 Protein; D009363:Neoplasm Proteins / Q000235:genetics*; D009687:Nuclear Proteins; D010375:Pedigree; D010641:Phenotype; D016133:Polymerase Chain Reaction; D018807:Polymorphism, Single-Stranded Conformational; D011518:Proto-Oncogene Proteins / Q000235:genetics*
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C094443:G-T mismatch-binding protein; 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