Ataxia telangiectasia (A-T) is a rare autosomal recessive disease characterized by progressive neurodegeneration and cerebellar ataxia. A-T is causally linked to defects in ATM, a master regulator of the response to and repair of DNA double-strand breaks. The molecular basis of cerebellar atrophy and neurodegeneration in A-T patients is unclear. Here we report and examine the significance of increased PARylation, low NAD⁺, and mitochondrial dysfunction in ATM-deficient neurons, mice, and worms. Treatments that replenish intracellular NAD⁺ reduce the severity of A-T neuropathology, normalize neuromuscular function, delay memory loss, and extend lifespan in both animal models. Mechanistically, treatments that increase intracellular NAD⁺ also stimulate neuronal DNA repair and improve mitochondrial quality via mitophagy. This work links two major theories on aging, DNA damage accumulation, and mitochondrial dysfunction through nuclear DNA damage-induced nuclear-mitochondrial signaling, and demonstrates that they are important pathophysiological determinants in premature aging of A-T, pointing to therapeutic interventions.

BACKGROUND:

The nucleosomal histone protein H2AX is specifically phosphorylated (γ-H2AX) adjacent to DNA double-strand breaks (DSBs) and is used for quantifying DSBs. Many chemotherapies and ionizing radiation (IR) used in cancer treatment result in DSBs. Therefore, γ-H2AX has a significant potential as a biomarker in evaluating patient sensitivity and responsiveness to IR and chemotherapy.

METHODS:

Here, we report a flow cytometry-based quantification of γ-H2AX (FCM-γ-H2AX assay) customized for clinical practice.

RESULTS:

We validated that our method is able to detect DNA damage in peripheral blood mononuclear cells (PBMCs) treated with DSB inducing agents. The method also detected the DNA repair deficiency in PBMCs treated with DNA repair inhibitors, as well as the deficiency in DNA repair signaling in PBMCs from two ataxia telangiectasia patients.

CONCLUSIONS:

The FCM-γ-H2AX assay has sufficient analytical sensitivity and precision to measure levels of DNA damage and DNA repair for clinical purposes. © 2016 International Clinical Cytometry Society.

© 2016 International Clinical Cytometry Society.

The authors review ataxia telangiectasia, emphasizing historical aspects, genetic discoveries, and the clinical presentations of the classical and atypical forms. In fact, ataxia telangiectasia represents a multisystem entity with pleomorphic neurological and systemic manifestations. ATM syndrome is proposed as a more adequate designation for this entity.

RATIONALE:

Forced vital capacity (FVC) values decrease with progress of the disease in Ataxia telangiectasia (AT).

OBJECTIVE:

To study the effect of this process on airway obstruction determination and life span in AT.

METHODS:

Clinical data and yearly best spirometry maneuvers were collected retrospectively from 37 AT patients (196 spirometry tests) during 5.4 ± 1.8yrs (initial age 4-21 y). Twelve patients were walking (7 of them had recurrent respiratory system infections); 25 subjects were confined to wheelchair, of them 8 patients were towards end-stage lung disease. Spirometry indices included Forced Vital Capacity (FVC), mid-expiratory-flow (FEF25-75), and tidal volume (VT). We calculated FEF25-75/FVC and VT/FVC ratios.

RESULTS:

FVC declined from 67 ± 8 while walking to 19 ± 6 %predicted values. FEF25-75 values that were elevated (116 ± 23 %predicted) while walking, decreased to 69 ± 27 %predicted at end-stage where 7 patients responded to bronchodilators. VT/FVC ratio was 0.25 ± 0.06 while walking, increased to 0.35 once on wheelchairs, and further increased to 0.57 ± 0.19 at end-stage disease. FEF25-75/FVC ratio was 2.54 ± 0.70 above normal (∼1.0) increasing to 4.16 ± 0.75 at end stage. A sharp elevation was seen in FEF25-75/FVC ratio when FEV1 was still ∼45 %predicted and 2-years prior to death.

CONCLUSIONS:

Having a low baseline-FVC (60% predicted) artificially raises FEF25-75 values, so FEF25-75 of "mild obstruction" values may indicate severe airway obstruction in AT subjects. VT/FVC and FEF25-75/FVC ratios may therefore assist in revealing higher than normal breathing effort. The results further suggest adding VT/FVC and FEF25-75/FVC ratios to pulmonary function assessments in patients with AT.

Copyright © 2015 Elsevier Ltd. All rights reserved.

Genetic predisposition for childhood cancer is under diagnosed. Identifying these patients may lead to therapy adjustments in case of syndrome-related increased toxicity or resistant disease and syndrome-specific screening programs may lead to early detection of a further independent malignancy. Cancer surveillance might also be warranted for affected relatives and detection of a genetic mutation can allow for reproductive counseling. Here we present an easy-to-use selection tool, based on a systematic review of pediatric cancer predisposing syndromes, to identify patients who may benefit from genetic counseling. The selection tool involves five questions concerning family history, the type of malignancy, multiple primary malignancies, specific features and excessive toxicity, which results in the selection of those patientsthat may benefit from referral to a clinical geneticist.

ATM kinase modulates pathways implicated in premature ageing and ATM genotype predicts survival, yet immunodeficiency in ataxiatelangiectasia is regarded as mild and unrelated to age. We address this paradox in a molecularly characterised sequential adult cohort with classical and mild variant ataxia telangiectasia. Immunodeficiency has the characteristics of premature ageing across multiple cellular and molecular immune parameters. This immune ageing occurs without previous CMV infection. Age predicts immunodeficiency in genetically homogeneous ataxia telangiectasia, and in comparison with controls, calendar age is exceeded by immunological age defined by thymic naïve CD4+ T cell levels. Applying ataxia telangiectasia as a model of immune ageing, pneumococcal vaccine responses, characteristically deficient in physiological ageing, are predicted by thymic naïve CD4+ T cell levels. These data suggest inherited defects of DNA repair may provide valuable insight into physiological ageing. Thymic naïve CD4+ T cells may provide a biomarker for vaccine responsiveness in elderly cohorts.

Ataxia-telangiectasia (A-T) is a rare autosomal recessive disorder caused by mutations in the ATM gene, resulting in faulty repair of breakages in double-stranded DNA. The clinical phenotype is complex and is characterized by neurologic abnormalities, immunodeficiencies, susceptibility to malignancies, recurrent sinopulmonary infections, and cutaneous abnormalities. Lung disease is common in patients with A-T and often progresses with age and neurological decline. Diseases of the respiratory system cause significant morbidity and are a frequent cause of death in the A-T population. Lung disease in this population is thought to exhibit features of one or more of the following phenotypes: recurrent sinopulmonary infections with bronchiectasis, interstitial lung disease, and lung disease associated with neurological abnormalities. Here, we review available evidence and present expert opinion on the diagnosis, evaluation, and management of lung disease in A-T, as discussed in a recent multidisciplinary workshop. Although more data are emerging on this unique population, many recommendations are made based on similarities to other more well-studied diseases. Gaps in current knowledge and areas for future research in the field of pulmonary disease in A-T are also outlined.

Ataxia telangiectasia is a rare, multiorgan neurodegenerative disorder with enhanced vulnerability to cancer and infection. Median survival in two large cohorts of patients with this disease, one prospective and one retrospective, is 25 and 19 years, with a wide range. Life expectancy does not correlate well with severity of neurological impairment.

Ataxia telangiectasia (AT) is a rare autosomal recessive disorder characterized by progressive ataxia, neurodegeneration, immunodeficiency, and cancer predisposition. Pathoanatomical studies reported a degeneration of cerebellar Purkinje cells as the striking feature of the disease. Although recent studies suggested the involvement of extracerebellar structures such as the brainstem and basal ganglia, this has rarely been studied in human AT. Thus, we performed a detailed cliniconeuroradiological investigation of 11 AT patients, aged 8 to 26 years by collecting clinical neurological data, ataxia scores, growth status, body mass index (BMI), growth hormone (GH), and insulin-like-growth factor 1 (IGF-1) and correlated them to extracerebellar neuroimaging findings in human AT. Neuroimaging was done by cranial and spine magnetic resonance imaging (MRI) with T1- and T2-weighted spin-echo and fluid attenuated inversion recovery sequences. We compared clinical and neuroradiological findings of six patients with IGF-1 levels and BMI below the third percentile to five patients with normal IGF-1 serum levels and BMI above the third percentile. Three of the six first mentioned patients older than 20 years and two patients older than 12 years showed noticeable high Klockgether ataxia scores above 25 points. Three of these patients presented with marked hyperintense lesions in the cerebral white matter of T2-weighted MR images. Interestingly, all six patients suffered from marked spinal atrophy. Two of the patients presented with severe extra-pyramidal symptoms, but only one patient showed associated MRI abnormalities of the basal ganglia. MRI in patients with normal IGF-1 levels showed the expected cerebellar lesions in four patients, whereas spinal atrophy was found only in two patients. There was no affection of the cerebral white matter or basal ganglia in this group. We conclude that central cerebral white matter affection, spinal atrophy, and extrapyramidal symptoms are more often present in patients with pronounced deficiency of the GH/IGF-1 axis accompanied by markedly reduced body weight and high ataxia scores. This may point to a major role of IGF-1 and nutritional status in neuroprotective signaling.

Serum interleukin (IL)-8 levels were measured in 50 patients with ataxia telangiectasia (A-T) and 22 without A-T. In a cross-sectional study, the geometric mean of IL-8 level was significantly higher in the patients with A-T (P <.0001). Elevated serum IL-8 levels in patients with A-T suggest that systemic inflammation may contribute to the disease phenotype.

One prominent feature of patients with the autosomal recessive disease ataxia telangiectasia (AT) is somatic growth retardation. Due to their essential roles in development we examined levels of insulin-like growth factor-I (IGF-I) as well as its main binding protein (IGFBP-3) in a group of AT patients. Growth status of 19 patients was assessed by body mass index (BMI) and nutritional protocols. As suspected, BMI was low in AT patients despite adequate nutrition. Serum levels of IGF-I were found to be below the 3rd percentile in 9 (56%) out of 16 patientsand of IGFBP-3 in 13 (81%) out of 16 patients. Our observations demonstrate that IGF-I and IGFBP-3 levels reflect the impaired growthstatus in patients with AT.

Ataxia telangiectasia (AT) is an infrequent condition, which is difficult to diagnose in children. The objective was to describe the evolution of all affected patients controlled in our hospital and to highlight the keys for an early diagnosis considering the variability of immunological disorders. The present study is a retrospective review of all patients diagnosed and controlled of AT in our hospital. Twelve patients were found, including two couples of siblings. The most frequent reason for consultation was unstable gait. Seven patients suffered repeated infections, being pneumonia the most frequent cause of infection, followed by sinusitis. One of the patients developed Burkitt's lymphoma, and another patient, Hodgkin's lymphoma, which caused the death of the patient at the age of 11. A couple of siblings aged 17 and 22 years developed insulin-resistant diabetes mellitus. The most frequent immunity disorders were the IgG deficiency and the decrease of T lymphocytes. Seven patients were treated with non-specific gamma-globulin. By the end of the follow-up, 8 patients (ages ranged 7 to 12years) lost gait. Molecular genetic testing was conducted in patients who are still cared for in our hospital. Clinical suspicion of this entity will lead to an early diagnosis, the treatment of complications, and to provide genetic counselling for the families.

Ataxia-telangiectasia is a recessive genetic disorder (ATM is the mutated gene) of childhood with severe motor impairments and whereas homozygotes manifest the disorder, heterozygotes are asymptomatic. Structural brain imaging and post-mortem studies in individuals with ataxia-telangiectasia have reported cerebellar atrophy; but abnormalities of motor control characteristic of extrapyramidal dysfunction suggest impairment of broader motor networks. Here, we investigated possible dysfunction in other brain areas in individuals with ataxia-telangiectasia and tested for brain changes in asymptomatic relatives to assess if heterozygocity affects brain function. We used positron emission tomography and (18)F-fluorodeoxyglucose to measure brain glucose metabolism (quantified as µmol/100 g/min), which serves as a marker of brain function, in 10 adults with ataxia-telangiectasia, 19 non-affected adult relatives (12 siblings, seven parents) and 29 age-matched healthy controls. Statistical parametric mapping and region of interest analyses were used to compare individuals with ataxia-telangiectasia, asymptomatic relatives, and unrelated controls. We found that participants with ataxia-telangiectasia had lower metabolism in cerebellar hemispheres (14%, P < 0.001), anterior vermis (40%, P < 0.001) and fusiform gyrus (20%, P < 0.001) compared with controls or siblings, and lower metabolism in hippocampus (12%, P = 0.05) compared with controls, and showed significant intersubject variability (decreases in vermis ranged from 18% to 60%). Participants with ataxia-telangiectasia also had higher metabolism in globus pallidus (16%, P = 0.05), which correlated negatively with motor performance. Asymptomatic relatives had lower metabolism in anterior vermis (12%; P = 0.01) and hippocampus (19%; P = 0.002) than controls. Our results indicate that, in addition to the expected decrease in cerebellar metabolism, participants with ataxia-telangiectasia had widespread changes in metabolic rates including hyperactivity in globus pallidus indicative of basal ganglia involvement. Changes in basal ganglia metabolism offer potential insight into targeting strategies for therapeutic deep brain stimulation. Our finding of decreased metabolism in vermis and hippocampus of asymptomatic relatives suggests that heterozygocity influences the function of these brain regions.

Ataxia telangiectasia (A-T), also known as Louis-Bar Syndrome, is a rare genetic form of early-onset autosomal recessive ataxia. The clinical picture is characterized by a combination of neurological and systemic symptoms due to the mutation of the ataxia telangiectasia mutated (ATM) gene. In particular, the disease is characterized by cerebellar atrophy with progressive ataxia, cutaneous telangiectasias, higher incidence of malignancy (particularly lymphoid malignancy), radiosensitivity, immune deficiency, recurrent sinopulmonary infections, and high levels of alpha-fetoprotein in serum.

Copyright © 2018, StatPearls Publishing LLC.

We report a case of toxoplasmosis with bilateral maculopathy in a 7-year-old boy diagnosed with ataxia telangiectasia (AT) at age 6. AT manifests as ataxia, apraxia, telangiectasia, and dysarthria. Common ophthalmologic findings in AT include fine conjunctival telangiectasia. Patients also suffer from recurrent sinopulmonary infections; however, serious opportunistic infection is rarely diagnosed. At 8 years of age he developed disseminated Toxoplasma gondii (toxoplasmosis) infection and meningoencephalitis. This ophthalmologic finding and the subsequent toxoplasmosis meningoencephalitis have not been previously reported in AT.