PURPOSE: Germline missense variants of unknown significance in cancer-related genes are increasingly being identified with the expanding use of next-generation sequencing. The ataxia telangiectasia-mutated (ATM) gene on chromosome 11 has more than 1,000 germline missense variants of unknown significance and is a tumor suppressor. We aimed to determine if rare germline ATM variants are more frequent in chronic lymphocytic leukemia (CLL) compared with other hematologic malignancies and if they influence the clinical characteristics of CLL. METHODS: We identified 3,128 patients (including 825 patients with CLL) in our hematologic malignancy clinic who had received clinical-grade sequencing of the entire coding region of ATM. We ascertained the comparative frequencies of germline ATM variants in categories of hematologic neoplasms, and, in patients with CLL, we determined whether these variants affected CLL-associated characteristics such as somatic 11q deletion. RESULTS: Rare germline ATM variants are present in 24% of patients with CLL, significantly greater than that in patients with other lymphoid malignancies (16% prevalence), myeloid disease (15%), or no hematologic neoplasm (14%). Patients with CLL with germline ATM variants are younger at diagnosis and twice as likely to have 11q deletion. The ATM variant p.L2307F is present in 3% of patients with CLL, is associated with a three-fold increase in rates of somatic 11q deletion, and is a hypomorph in cell-based assays. CONCLUSION: Germline ATM variants cluster within CLL and affect the phenotype of CLL that develops, implying that some of these variants (such as ATM p.L2307F) have functional significance and should not be ignored. Further studies are needed to determine whether these variants affect the response to therapy or account for some of the inherited risk of CLL.

• MeSH
• ATM protein * genetika   MeSH
• chronická lymfatická leukemie * farmakoterapie   MeSH
• lidé MeSH
• mutace MeSH
• nádorové supresorové proteiny genetika   MeSH
• protein-serin-threoninkinasy genetika   terapeutické užití   MeSH
• proteiny buněčného cyklu genetika   MeSH
• teleangiektatická ataxie MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• ATM protein, human MeSH Prohlížeč
• ATM protein * MeSH
• nádorové supresorové proteiny MeSH
• protein-serin-threoninkinasy MeSH
• proteiny buněčného cyklu MeSH

The ATM-p53 DNA-damage response (DDR) pathway has a crucial role in chemoresistance in CLL, as indicated by the adverse prognostic impact of genetic aberrations of TP53 and ATM. Identifying and distinguishing TP53 and ATM functional defects has become relevant as epigenetic and posttranscriptional dysregulation of the ATM/p53 axis is increasingly being recognized as the underlying cause of chemoresistance. Also, specific treatments sensitizing TP53- or ATM-deficient CLL cells are emerging. We therefore developed a new ATM-p53 functional assay with the aim to (i) identify and (ii) distinguish abnormalities of TP53 versus ATM and (iii) enable the identification of additional defects in the ATM-p53 pathway. Reversed transcriptase multiplex ligation-dependent probe amplification (RT-MLPA) was used to measure ATM and/or p53-dependent genes at the RNA level following DNA damage using irradiation. Here, we showed that this assay is able to identify and distinguish three subgroups of CLL tumors (i.e., TP53-defective, ATM-defective and WT) and is also able to detect additional samples with a defective DDR, without molecular aberrations in TP53 and/or ATM. These findings make the ATM-p53 RT-MLPA functional assay a promising prognostic tool for predicting treatment responses in CLL.

• MeSH
• ATM protein genetika   metabolismus   MeSH
• biotest MeSH
• chemorezistence genetika   MeSH
• chronická lymfatická leukemie farmakoterapie   genetika   metabolismus   patologie   MeSH
• doxorubicin farmakologie   MeSH
• epigeneze genetická MeSH
• lidé MeSH
• multiplexová polymerázová řetězová reakce metody   MeSH
• mutace * MeSH
• nádorový supresorový protein p53 genetika   metabolismus   MeSH
• polymerázová řetězová reakce s reverzní transkripcí metody   MeSH
• poškození DNA MeSH
• protinádorové látky farmakologie   MeSH
• regulace genové exprese u leukemie * MeSH
• RNA nádorová genetika   MeSH
• senzitivita a specificita MeSH
• vidarabin analogy a deriváty   farmakologie   MeSH
• záření gama MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• ATM protein, human MeSH Prohlížeč
• ATM protein MeSH
• doxorubicin MeSH
• fludarabine MeSH Prohlížeč
• nádorový supresorový protein p53 MeSH
• protinádorové látky MeSH
• RNA nádorová MeSH
• vidarabin MeSH

ATM abnormalities are frequent in chronic lymphocytic leukemia and represent an important prognostic factor. Sole 11q deletion does not result in ATM inactivation by contrast to biallelic defects involving mutations. Therefore, the analysis of ATM mutations and their functional impact is crucial. In this study, we analyzed ATM mutations in predominantly high-risk patients using: i) resequencing microarray and direct sequencing; ii) Western blot for total ATM level; iii) functional test based on p21 gene induction after parallel treatment of leukemic cells with fludarabine and doxorubicin. ATM dysfunction leads to impaired p21 induction after doxorubicin exposure. We detected ATM mutation in 16% (22 of 140) of patients, and all mutated samples manifested demonstrable ATM defect (impaired p21 upregulation after doxorubicin and/or null protein level). Loss of ATM function in mutated samples was also evidenced through defective p53 pathway activation after ionizing radiation exposure. ATM mutation frequency was 34% in patients with 11q deletion, 4% in the TP53-defected group, and 8% in wild-type patients. Our functional test, convenient for routine use, showed high sensitivity (80%) and specificity (97%) for ATM mutations prediction. Only cells with ATM mutation, but not those with sole 11q deletion, were resistant to doxorubicin. As far as fludarabine is concerned, this difference was not observed. Interestingly, patients from both these groups experienced nearly identical time to first treatment. In conclusion, ATM mutations either alone or in combination with 11q deletion uniformly led to demonstrable ATM dysfunction in patients with chronic lymphocytic leukemia and mutation presence can be predicted by the functional test using doxorubicin.

• MeSH
• ATM protein antagonisté a inhibitory   genetika   fyziologie   MeSH
• chromozomální delece MeSH
• chronická lymfatická leukemie diagnóza   genetika   patologie   MeSH
• dospělí MeSH
• doxorubicin farmakologie   MeSH
• kohortové studie MeSH
• leukocyty mononukleární účinky léků   patologie   MeSH
• lidé středního věku MeSH
• lidé MeSH
• lidské chromozomy, pár 11 genetika   MeSH
• mutace genetika   MeSH
• retrospektivní studie MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• viabilita buněk účinky léků   fyziologie   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři nad 80 let MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• ATM protein, human MeSH Prohlížeč
• ATM protein MeSH
• doxorubicin MeSH