Germ-line mutations in MLH1 and MSH2 genes predispose to hereditary non-polyposis colorectal cancer (HNPCC) syndrome, but they do not predict a specific phenotype of the disease. We speculated that the ataxia-telangiectasia mutated gene (ATM) was a candidate gene to modulate the phenotypic expressio
High incidence of cancer in a family segregating a mutation of the ATM gene: Possible role of ATM heterozygosity in cancer
✍ Scribed by Jacques-Olivier Bay; Nancy Uhrhammer; David Pernin; Nadège Presneau; Andrei Tchirkov; Michèle Vuillaume; Valérie Laplace; Maria Grancho; Pierre Verrelle; Janet Hall; Yves-Jean Bignon
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 289 KB
- Volume
- 14
- Category
- Article
- ISSN
- 1059-7794
No coin nor oath required. For personal study only.
✦ Synopsis
Communicated by Anne-Lise Borresen-Dale
ATM mutations predispose cells to malignancy by promoting chromosomal instability. We have identified a family with multiple cancers that segregates a mutant allele of ATM, IVS61+2insTA, which causes skipping of exon 61 in the mRNA, as well as a previously undescribed polymorphism, IVS61+104C(54):T(46). The mutation was inherited by two sisters, one who developed breast cancer at age 39 and the second at age 44, from their mother, who developed kidney cancer at age 67. Molecular studies were undertaken to determine the role of the ATM gene in the development of cancer in this family. Studies of irradiated lymphocytes from both sisters revealed elevated numbers of chromatid breaks, typical of A-T heterozygotes. Studies on lymphoblastoid cell lines established from these individuals revealed abnormal p53 induction and apoptosis after DNA damage. Loss of heterozygosity (LOH) in the ATM region of chromosome 11q23.1 showed that the normal ATM allele was lost in the breast tumor of the older sister. LOH was not seen at the BRCA1 or BRCA2 loci. BRCA2 is not likely to be a cancer-predisposing gene in this family because each sister inherited different chromosomes 13 from each parent. The sisters share their maternal BRCA1 allele, although no mutation in this gene was detected in the family. Our findings suggest that haploinsufficiency at ATM may promote tumorigenesis, even though LOH at the locus supports a more classic two-hit tumor suppressor gene model.
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