ATM

Description

Ataxia-telangiectasia (A-T) is a recessive disorder resulting from germline mutation of the A-T mutated (ATM) gene on chromosome 11q. Upon sensing double-stranded breaks (DSB), the wild-type kinase encoded by ATM initiates the DNA-damage response by phosphorylating histone H2AX and, subsequently, various other proteins, such as BRCA1 and the MRE11–RAD50–NBS1 (MRN) complex, which are recruited to the damaged site. Additionally, ATM phosphorylates p53, resulting in expression of the cyclin-dependent kinase inhibitor p21 and leading to senescence or apoptosis. Somatic variants can result in inhibition or loss of these functions and can cause resistance to therapies that rely on inducing apoptosis via DSBs. Germline variants in A-T patients result in a predisposition to cancer, most frequently hematologic or breast. PARP inhibition has been studied for its potential in treating ATM mutated breast cancer patients.