The discovery of ATM should enhance understanding of AT and related syndromes and may allow the identification of AT heterozygotes, who are at increased risk of cancer.
Experimental evidence supporting the Damage Surveillance Network model is summarized, followed by a discussion of how defects in the ATM-dependent signal transduction network might account for the A-T phenotype and what insights this new understanding of A-T can offer regarding DNA damage response networks, genomic instability, and cancer.
ATM, the gene product mutated in the cancer susceptibility syndrome ataxia-telangiectasia, is related to proteins involved in DNA repair and cell-cycle control, perhaps explaining how ATM prevents carcinogenesis.
The ATM gene is responsible for the autosomal recessive disorder ataxia-telangiectasia (A-T), characterized by cerebellar degeneration, immunodeficiency and cancer predisposition.
The development of DNA-based methods for detection of unknown mutations and further characterization of ATM mutation pattern will facilitate identification of A-T carriers and assessment of their cancer risk.
Ataxia telangiectasia (AT) is a recessive syndrome, including cerebellar degeneration, immunologic defects and cancer predisposition, attributed to mutations in the recently isolated ATM (ataxia telangiectasia, mutated) gene.
Sixteen HR breast cancer patients showing mainly acute reactions (and seven HR patients with other cancers) were tested for ATM mutations using the restriction endonuclease fingerprinting assay.
Breast and gastric cancers appear to be the most frequent malignancies in A-T carriers and one ATM germ-line mutation has been described in a breast/gastric cancer family.
The ATM gene deficient in ataxia-telangiectasia, a recessive multisystem disease associated with a high risk of lymphomas and leukemias, was found previously to be inactivated in a rare sporadic malignancy, T-cell prolymphocytic leukemia (T-PLL), which is often associated with cytogenetic aberrations of chromosome 14.
They will also enable the Costa Rican population to be used as a model for analyzing the role of ATM heterozygosity in cancer development and other disorders.
ATM knockout mice have been created by several groups, and recapitulate the immunodeficiency, radiosensitivity, cancer risk, and fertility defects of A-T, although the effect on the cerebellum is slight.
Mutations in the ATM gene located on the long arm of chromosome 11 at 11q22-23 cause ataxia-telangiectasia, an autosomal recessive disorder that is associated with increased incidence of malignancy and, particularly, lymphoid tumors.
The results presented here strongly suggest the possibility that a tissue RAS may also be present in the breast, closely coupled to the provision of angiotensin II to the AT1 receptors in ductal epithelial cells.This mechanism is disrupted in cancer.
Because of its role in maintaining genomic stability, and the high risk of cancer to homozygotes, ATM is a candidate gene for inactivation in the evolution of chromosomal instability in tumor cells.
For example, the gene ataxia telangiectasia mutated (ATM) has recently been shown to be a tumour suppressor gene in T-cell prolymphocytic leukaemia, and there is increasing evidence that individuals with one mutated ATM or Nijmegen breakage syndrome (NBS1) allele have an increased predisposition to cancer.
Thus, although it is still controversial whether ATM mutation carriers are at higher risk for cancer during adulthood, our findings based on in vitro biological indicators support the notion that at least some of such carriers are at a higher risk for cancer development than those without ATM mutation.
MEC1 is a homolog of ATM, mutations in which cause ataxia telangiectasia (A-T), a disease characterized by various neurologic and immunologic abnormalities, a predisposition for cancer, and a cellular defect in repair of DSBs.
Cancer-specific survival was significantly reduced in patients whose tumors exhibited LOH of markers D11S2179 (within the ATM gene), D11S1778, D11S1294, and D11S1818.
The minimal consensus deletion comprises a segment, which contains the ATM gene presenting an interesting candidate gene, as mutations in ATM predispose A-T patients to lymphoid malignancies.
Analyses of ATM mutations in A-T patients and in sporadic tumors suggest the existence of two classes of ATM mutation: null mutations that lead to A-T and dominant negative missense mutations that may predispose to cancer in the heterozygous state.