Germline hMSH2 and hMLH1 gene mutations in incomplete HNPCC families.
Hereditary non-polyposis colon cancer (HNPCC) is a common hereditary disease characterized by a predisposition to an early onset of colorectal cancer. The majority of the HNPCC families carry germline mutations of either hMSH2 or hMLH1 genes, whereas germline mutations of hPMS1 and hPMS2 genes have rarely been observed. Almost all of the germline mutations reported so far concern typical HNPCC families. However, there are families that display aggregations of colon cancer even though they do not fulfil all HNPCC criteria (incomplete HNPCC families) as well as sporadic cases of early onset colon cancers that could be related to germline mutations of these genes. Therefore, we screened germline mutations of hMSH2 and hMLH1 genes in 3 groups of patients from France and Turkey: typical HNPCC (n = 3), incomplete HNPCC (n = 9) and young patients without apparent familial history (n = 7). By in vitro synthesis of protein assay, heteroduplex analysis and direct genomic sequencing, we identified 1 family with hMSH2 mutation and 5 families with hMLH1 mutations. Two of the 3 HNPCC families (66%) displayed hMLH1 germline mutations. Interestingly, 4 of 9 families with incomplete HNPCC (44%) also displayed mutations of hMSH2 or hMLH1 genes. In contrast, no germline mutation of these genes was found in 7 young patients. Our results show that germline mutations of hMSH2 and hMLH1 genes contribute to a significant fraction of familial predisposition to colon cancer cases that do not fulfil all diagnostic criteria of HNPCC.
Wang
Q
Q
Laboratoire d'Oncologie Moléculaire, Unité INSERM 453, Centre Léon Bérard, Lyon, France.
Desseigne
F
F
Lasset
C
C
Saurin
J C
JC
Navarro
C
C
Yagci
T
T
Keser
I
I
Bagci
H
H
Luleci
G
G
Gelen
T
T
Chayvialle
J A
JA
Puisieux
A
A
Ozturk
M
M
D048868:Adaptor Proteins, Signal Transducing; D000328:Adult; D000368:Aged; D015153:Blotting, Western; D002352:Carrier Proteins; D003110:Colonic Neoplasms / Q000235:genetics*; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000235:genetics*; D004273:DNA, Neoplasm / Q000032:analysis; D004268:DNA-Binding Proteins; 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* / Q000378:metabolism; D009687:Nuclear Proteins; D010375:Pedigree; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D017421:Sequence Analysis
D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D004273:DNA, Neoplasm; 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