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Ataxia-telangiectasia (A-T) is an autosomal recessive neurodegenerative disorder characterized by radiosensitivity, genomic instability, and predisposition to cancer. A-T is caused by biallelic mutations in the ataxia-telangiectasia mutated (ATM) gene, but [...]

The frequency of splicing mutations was studied in an independent population of people with ataxia telangiectasia (AT). Sixty-two mutations were found, of which 30 (48%) affected splicing accuracy. Ten of the 30 mutations involved canonical splice sites. Novel splice sites were created by three of the mutations. In addition, nonsense and missense mutations were identified that indirectly affected splicing. There were also cases of variant splicing in which no underlying mutation was found.

Ataxia-telangiectasia (A-T) has ATM as the underlying gene. It encodes a large protein kinase with a phosphatidylinositol 3-kinase-like domain. ATM protein levels have been measured in six A-T variants and the ATM genes searched for mutations. Findings show there is a larger range of phenotypes associated with ATM mutations than had been known and show that some A-T variant phenotypes come from ATM mutations. Some of those are without telangiectasia. A-T is a complex multisystem autosomal recessive disorder.

Ten ethnic populations have been studied to determine common mutations in the ATM gene associated with ataxia-telangiectasia (A-T). Ninety-two truncating mutations were found by screening 140 mutant alleles. Founder-effect mutations were found in Costa Rican, Norwegian, Polish, Italian and Amish/Mennonite populations. Genomic mutations and effects on cDNA were examined to enable assessment of ATM heterozygotes in relation to susceptibility to other diseases.

A gene, ATM, that is mutated in the autosomal recessive disorder ataxia telangiectasia (AT) was identified by positional cloning on chromosome 11q22-23. AT is characterized by cerebellar degeneration, immunodeficiency, chromosomal instability, cancer predisposition, radiation sensitivity, and cell cycle abnormalities. The disease is genetically heterogeneous, with four complementation groups that have been suspected to represent different genes. ATM, which has a transcript of 12 kilobases, was found to be mutated in AT patients from all complementation groups, indicating that it is probably the sole gene responsible for this disorder. A partial ATM complementary DNA clone of 5.9 kilobases encoded a putative protein that is similar to several yeast and mammalian phosphati-dylinositol-3' kinases that are involved in mitogenic signal transduction, meiotic recombination, and cell cycle control. 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., Ataxia telangiectasia is inherited in a monogenic, autosomal recessive manner, with a worldwide incidence of 1 in 40,000 to 1 in 100,000 [1]. Ataxia telangiectasia is usually first noticed in [...]

Abstract Ataxia-telangiectasia (A-T) is a complex multisystem disorder characterized by progressive neurological impairment, variable immunodeficiency and oculo-cutaneous telangiectasia. A-T is a member of chromosomal breakage syndromes and it is caused by a mutation in the ataxia-telangiectasia mutated (ATM) gene. Because of a wide clinical heterogeneity, A-T is often difficult to diagnose in children. We report an unusual case of a 3-year-old boy affected by A-T who presented exclusively with extensive cutaneous granulomatosis and severe combined immunodeficiency, without neurological abnormalities, at the time of diagnosis. This case clearly emphasizes the variable presentation of A-T syndrome and highlights the difficulties in the early diagnosis of A-T. A-T should be considered in children with evidence of combined humoral and cellular immunodeficiency associated with unexplained skin granulomatous lesions, even in the absence of the classic features of this syndrome.

Oxidative stress has been shown to play a crucial role in the pathophysiology of the neurodegenerative disease Ataxia Telangiectasia. We have recently demonstrated that Dexamethasone treatment is able to counteract the oxidative state by promoting nuclear factor erythroid 2-related factor 2 (NRF2) nuclear accumulation. However, substantial gaps remain in our knowledge of the underlying molecular mechanism(s) according to which Dexamethasone acts as an NRF2 inducer. Herein we investigate the possible effects of the drug on the main NRF2 activation pathways by initially focusing on key kinases known to differently affect NRF2 activation. Neither AKT nor ERK1/2, known to be NRF2-activating kinases, were found to be activated upon Dexamethasone treatment, thus excluding their involvement in the transcription factor nuclear shift. Likewise, GSK3 inactivating kinase was not inhibited, thus ruling out its role in NRF2 activation. On the other hand, p38 MAPK, another NRF2-inhibitory kinase, was indeed switched-off in Ataxia Telangiectasia cells by Dexamethasone-mediated induction of DUSP1 phosphatase, and therefore it appeared that it might account for NRF2 triggering. However, this mechanism was excluded by the use of a selective p38 inhibitor, which failed to cause a significant NRF2 nuclear shift and target gene induction. Finally, dexamethasone effects on the classical oxidative pathway orchestrated by KEAP1 were addressed. Dexamethasone was found to decrease the expression of the inhibitor KEAP1 at both mRNA and protein levels and to induce the shift from the reduced to the oxidized form of KEAP1, thus favouring NRF2 translocation into the nucleus. Furthermore, preliminary data revealed very low levels of the negative regulator Fyn in Ataxia Telangiectasia cells, which might account for the prolonged NRF2-activated gene expression. [ABSTRACT FROM AUTHOR]

Background A taxia telangiectasia (A-T) is a neurodegenerative disorder. While patients with classic A-T generally die in their 20s, some patients with variant A-T, who have residual ataxia-telangiectasia mutated (AT M) kinase activity, have a milder phenotype. We noticed two commonly occurring ATM mutations that appeared to be associated with prolonged survival and decided to study patients carrying one of these mutations. Methods Data were retrospectively collected from the Dutch, Italian, German and French A-T cohorts. To supplement these data, we searched the literature for patients with identical genotypes. Results T his study included 35 patients who were homozygous or compound heterozygous for the ATM c.3576G>A; p.(Ser1135_Lys1192del58) mutation and 24 patients who were compound heterozygous for the ATM c.8147T>C; p.(Val2716Ala) mutation. Compared with 51 patients with classic A-T from the Dutch cohort, patients with ATM c.3576G>A had a longer survival and were less likely to develop cancer, respiratory disease or immunodeficiency. This was also true for patients with ATM c.8147T>C, who additionally became wheelchair users later in life and had fewer telangiectasias. The oldest patient with A-T reported so far was a 78-year-old patient who was compound heterozygous for ATM c.8147T>C. AT M kinase activity was demonstrated in cells from all patients tested with the ATM c.8147T>Cmutant protein and only at a low level in some patients with ATM c.3576G>A. Conclusion C ompared with classic A-T, the presence of ATM c.3576G>A results in a milder classic phenotype. Patients with ATM c.8147T>C have a variant phenotype with prolonged survival, which in exceptional cases may approach a near-normal lifespan. [ABSTRACT FROM AUTHOR]

Ataxia telangiectasia (A-T) is an incurable and rare hereditary syndrome. In recent times, treatment with glucocorticoid analogues has been shown to improve the neurological symptoms that characterize this condition, but the molecular mechanism of action of these analogues remains unknown. Hence, the aim of this study was to gain insight into the molecular mechanism of action of glucocorticoid analogues in the treatment of A-T by investigating the role of Dexamethasone (Dexa) in A-T lymphoblastoid cell lines. We used 2DE and tandem MS to identify proteins that were influenced by the drug in A-T cells but not in healthy cells. Thirty-four proteins were defined out of a total of 746±63. Transcriptome analysis was performed by microarray and showed the differential expression of 599 A-T and 362 wild type (WT) genes and a healthy un-matching between protein abundance and the corresponding gene expression variation. The proteomic and transcriptomic profiles allowed the network pathway analysis to pinpoint the biological and molecular functions affected by Dexamethasone in Dexa-treated cells. The present integrated study provides evidence of the molecular mechanism of action of Dexamethasone in an A-T cellular model but also the broader effects of the drug in other tested cell lines. [ABSTRACT FROM AUTHOR]

Ataxia telangiectasia (AT) is a rare incurable genetic disease caused by biallelic mutations in the Ataxia telangiectasia-mutated gene. Intra-erythrocyte infusion of dexamethasone improves clinical outcomes in AT patients; however, the molecular mechanisms that lead to this improvement remain unknown. Hence, to gain a better understanding of these mechanisms, we assessed the effects of glucocorticoid administration on gene expression in the blood of AT patients. Whole blood was obtained from nine children enrolled in a phase two clinical trial, who were being treated with dexamethasone (AT Dexa), from six untreated AT patients (AT) and from six healthy volunteers (WT). CodeLink Whole Genome Bioarrays were used to assess transcript expression. The reliability of the differentially expressed genes (DEGs) was verified by qRT-PCR analysis. The enriched Gene Ontology (GO) terms and the pathways of the Kyoto Encyclopedia of Genes and Genomes (KEGG) of DEGs obtained by group comparisons were achieved using the Database for Annotation, Visualization and Integrated Discovery (DAVID). Functional network analyses were computed by Reactome FI. The likely involved transcription factors were revealed by iRegulon. Among the identified DEGs influenced by the pathology and restored by dexamethasone, we detected 522 upregulated probes coding for known proteins, while 22 probes were downregulated, as they were in healthy subjects. These results provide useful information and represent a first step towards gaining a better understanding of the underlying mechanisms of the effects of dexamethasone on AT patients. [ABSTRACT FROM AUTHOR]

Background: Ataxia Telangiectasia (AT) is a rare incurable genetic disease, caused by biallelic mutations in the Ataxia Telangiectasia-Mutated (ATM) gene. Treatment with glucocorticoid analogues has been shown to improve the neurological symptoms that characterize this syndrome. Nevertheless, the molecular mechanism underlying the glucocorticoid action in AT patients is not yet understood. Recently, we have demonstrated that Dexamethasone treatment may partly restore ATM activity in AT lymphoblastoid cells by a new ATM transcript, namely ATMdexa1.Results: In the present study, the new ATMdexa1 transcript was also identified in vivo, specifically in the PMBCs of AT patients treated with intra-erythrocyte Dexamethasone (EryDex). In these patients it was also possible to isolate new "ATMdexa1 variants" originating from canonical and non-canonical splicing, each containing the coding sequence for the ATM kinase domain. The expression of the ATMdexa1 transcript family was directly related to treatment and higher expression levels of the transcript in patients' blood correlated with a positive response to Dexamethasone therapy. Neither untreated AT patients nor untreated healthy volunteers possessed detectable levels of the transcripts. ATMdexa1 transcript expression was found to be elevated 8 days after the drug infusion, while it decreased 21 days after treatment.Conclusions: For the first time, the expression of ATM splicing variants, similar to those previously observed in vitro, has been found in the PBMCs of patients treated with EryDex. These findings show a correlation between the expression of ATMdexa1 transcripts and the clinical response to low dose dexamethasone administration. [ABSTRACT FROM AUTHOR]

Ataxia telangiectasia (A-T) is a rare incurable neurodegenerative disease caused by biallelic mutations in the gene for ataxia-telangiectasia mutated ( ATM). The lack of a functional ATM kinase leads to a pleiotropic phenotype, and oxidative stress is considered to have a crucial role in the complex physiopathology. Recently, steroids have been shown to reduce the neurological symptoms of the disease, although the molecular mechanism of this effect is largely unknown. In the present study, we have demonstrated that dexamethasone treatment of A-T lymphoblastoid cells increases the content of two of the most abundant antioxidants [glutathione ( GSH) and NADPH] by up to 30%. Dexamethasone promoted the nuclear accumulation of the transcription factor nuclear factor (erythroid-derived 2)-like 2 to drive expression of antioxidant pathways involved in GSH synthesis and NADPH production. The latter effect was via glucose 6-phosphate dehydrogenase activation, as confirmed by increased enzyme activity and enhancement of the pentose phosphate pathway rate. This evidence indicates that glucocorticoids are able to potentiate antioxidant defenses to counteract oxidative stress in ataxia telangiectasia, and also reveals an unexpected role for dexamethasone in redox homeostasis and cellular antioxidant activity. [ABSTRACT FROM AUTHOR]

Sequencing of sarcomere protein genes in patients fulfilling the clinical diagnostic criteria for hypertrophic cardiomyopathy (HCM) identifies a disease-causing mutation in 35% to 60% of cases. Age at diagnosis and family history may increase the yield of mutations screening. In order to assess whether Next-Generation Sequencing (NGS) may fulfil the molecular diagnostic needs in HCM, we included 17 HCM-related genes in a sequencing panel run on PGM IonTorrent. We selected 70 HCM patients, 35 with early (≼25 years) and 35 with late (≽65 years) diagnosis of disease onset. All samples had a 98.6% average of target regions, with coverage higher than 20x (mean coverage 620x). We identified 41 different mutations (seven of them novel) in nine genes: MYBPC3 (17/41 = 41%); MYH7 (10/41 = 24%); TNNT2, CAV3 and MYH6 (3/41 = 7.5% each); TNNI3 (2/41 = 5%); GLA, MYL2, and MYL3 (1/41=2.5% each). Mutation detection rate was 30/35 (85.7%) in early-onset and 8/35 (22.9%) in late-onset HCM patients, respectively (p < 0.0001). The overall detection rate for patients with positive family history was 84%, and 90.5% in patients with early disease onset. In our study NGS revealed higher mutations yield in patients with early onset and with a family history of HCM. Appropriate patient selection can increase the yield of genetic testing and make diagnostic testing cost-effective. [ABSTRACT FROM AUTHOR]

Ataxia-Telangiectasia is a rare multisystem autosomal recessive disorder [OMIM 208900], caused by mutations in Ataxia-Telangiectasia Mutated gene. It is characterized by neurological, immunological and cutaneous involvement. Granulomas have been previously reported in Ataxia-Telangiectasia patients, even if acne rosacea has not been described. We report a case of a young Ataxia-Telangiectasia patient with a severe immunological and neurological involvement, who developed granulomatous skin lesions diagnosed by skin biopsy as acne rosacea. Considering the severe clinical picture and the lack of improvement to multiple topic and systemic therapies, treatment with Isotretinoin was started and the skin lesions disappeared after five months. However the therapy was stopped due to drug-hepatotoxicity. Systemic treatment with Isotretinoin should be carefully considered in patient with Ataxia-Telangiectasia for the treatment of multi-drug resistant acne rosacea, however its toxicity may limit long-term use and the risk/benefit ratio of the treatment should be evaluated. [ABSTRACT FROM AUTHOR]

Background: PIK3CA-related overgrowth spectrum (PROS) include a group of disorders that affect only the terminal portion of a limb, such as type I macrodactyly, and conditions like fibroadipose overgrowth (FAO), megalencephaly-capillary malformation (MCAP) syndrome, congenital lipomatous asymmetric overgrowth of the trunk, lymphatic, capillary, venous, and combined-type vascular malformations, epidermal nevi, skeletal and spinal anomalies (CLOVES) syndrome and Hemihyperplasia Multiple Lipomatosis (HHML). Heterozygous postzygotic PIK3CA mutations are frequently identified in these syndromes, while timing and tissue specificity of the mutational event are likely responsible for the extreme phenotypic variability observed. Methods: We carried out a combination of Sanger sequencing and targeted deep sequencing of genes involved in the PI3K/AKT/mTOR pathway in three patients (1 MCAP and 2 FAO) to identify causative mutations, and performed immunoblot analyses to assay the phosphorylation status of AKT and P70S6K in affected dermal fibroblasts. In addition, we evaluated their ability to grow in the absence of serum and their response to the PI3K inhibitors wortmannin and LY294002 in vitro. Results and Conclusion: Our data indicate that patients’ cells showed constitutive activation of the PI3K/Akt pathway. Of note, PI3K pharmacological blockade resulted in a significant reduction of the proliferation rate in culture, suggesting that inhibition of PI3K might prove beneficial in future therapies for PROS patients. [ABSTRACT FROM AUTHOR]

Objective. The aim of this study was to evaluate the prevalence of most common mutations and intron 8 5T (IVS8-5T) polymorphism of CFTR gene in Italian: a) azoospermic males; b) non azoospermic subjects, male partners of infertile couples enrolled in assisted reproductive technology (ART) programs. Material and methods. We studied 242 subjects attending our Andrology Unit (44 azoospermic subjects and 198 non azoospermic subjects, male partners of infertile couples enrolled in ART programs). Semen analysis, molecular analysis for CFTR gene mutations and genomic variant of IVS8-5T polymorphic tract, karyotype and chromosome Y microdeletions, hormonal profile (LH, FSH, Testosterone) and seminal biochemical markers (fructose, citric acid and L-carnitine) were carried out. Results. The prevalence of the common CFTR mutations and/or the IVS8-5T polymorphism was 12.9% (4/31 cases) in secretory azoospermia, while in obstructive azoospermia was 84.6% (11/13 cases; in these, the most frequent mutations were the F508del, R117H and W1282X). Regarding the non azoospermic subjects, the prevalence of the CFTR and/or the IVS8-5T polymorphism was 11.1% (11/99 cases) in severe dyspermia, 8.1% (6/74 cases) in moderate dyspermia and finally 4.0% (1/25 cases) in normospermic subjects. Conclusions. This study confirms the highly significant prevalence of CFTR mutations in males with bilateral absence of the vas deferens or ejaculatory ducts obstruction compared with subjects with secretory azoospermia. Moreover, the significant prevalence of mutations in severely dyspermic subjects may suggest the possible involvement of CFTR even in the spermatogenic process. This could explain the unsatisfactory recovery of sperm from testicular fine needle aspiration in patients affected by genital tract blockage. [ABSTRACT FROM AUTHOR]

Background Ataxia Teleangiectasia [AT] is a rare neurodegenerative disease characterized by early onset ataxia, oculocutaneous teleangiectasias, immunodeficiency, recurrent infections, radiosensitivity and proneness to cancer. No therapies are available for this devastating disease. Recent observational studies in few patients showed beneficial effects of short term treatment with betamethasone. To avoid the characteristic side effects of long-term administration of steroids we developed a method for encapsulation of dexamethasone sodium phosphate (DSP) into autologous erythrocytes (EryDex) allowing slow release of dexamethasone for up to one month after dosing. Aims of the study were: the assessment of the effect of EryDex in improving neurological symptoms and adaptive behaviour of AT patients; the safety and tolerability of the therapy. Methods Twenty two patients (F:M = 1; mean age 11.2 ± 3.5) with a confirmed diagnosis of AT and a preserved or partially supported gait were enrolled for the study. The subjects underwent for six months a monthly infusion of EryDex. Ataxia was assessed by the International Cooperative Ataxia Rating Scale (ICARS) and the adaptive behavior by Vineland Adaptive Behavior Scales (VABS). Clinical evaluations were performed at baseline and 1, 3, and 6 months. Results An improvement in ICARS (reduction of the score) was detected in the intention-to-treat (ITT) population (n = 22; p = 0.02) as well as in patients completing the study (per protocol PP) (n = 18; p = 0.01), with a mean reduction of 4 points (ITT) or 5.2 points (PP). When compared to baseline, a significant improvement were also found in VABS (increase of the score) (p < 0.0001, ITT, RMANOVA), with statistically significant increases at 3 and 6 months (p < 0.0001). A large inter-patient variability in the incorporation of DSP into erythrocytes was observed, with an evident positive effect of higher infusion dose on ICARS score decline. Moreover a more marked improvement was found in less neurologically impaired patients. Finally, a 19 month-extension study involving a subgroup of patients suggested that Erydex treatment can possibly delay the natural progression of the disease. EryDex was well tolerated; the most frequent side effects were common AT pathologies. Conclusions EryDex treatment led to a significant improvement in neurological symptoms, without association with the typical steroid side effects. Trial registration Current Controlled Trial 2010-022315-19SpA [ABSTRACT FROM AUTHOR]

DNA damage can activate the oncosuppressor protein ataxia telangiectasia mutated (ATM), which phosphorylates the histone H2AX within characteristic DNA damage foci. Here, we show that ATM undergoes an activating phosphorylation in syncytia elicited by the envelope glycoprotein complex (Env) of human immunodeficiency virus-1 (HIV-1) in vitro. This was accompanied by aggregation of ATM in discrete nuclear foci that also contained phospho-histone H2AX. DNA damage foci containing phosphorylated ATM and H2AX were detectable in syncytia present in the brain or lymph nodes from patients with HIV-1 infection, as well as in a fraction of blood leukocytes, correlating with viral status. Knockdown of ATM or of its obligate activating factor NBS1 (Nijmegen breakage syndrome 1 protein), as well as pharmacological inhibition of ATM with KU-55933, inhibited H2AX phosphorylation and prevented Env-elicited syncytia from undergoing apoptosis. ATM was found indispensable for the activation of MAP kinase p38, which catalyzes the activating phosphorylation of p53 on serine 46, thereby causing p53 dependent apoptosis. Both wild type HIV-1 and an HIV-1 mutant lacking integrase activity induced syncytial apoptosis, which could be suppressed by inhibiting ATM. HIV-1-infected T lymphoblasts from patients with inactivating ATM or NBS1 mutations also exhibited reduced syncytial apoptosis. Altogether these results indicate that apoptosis induced by a fusogenic HIV-1 Env follows a pro-apoptotic pathway involving the sequential activation of ATM, p38MAPK and p53. [ABSTRACT FROM AUTHOR]

The gene for ataxia-telangiectasia (A-T:MIM: #208900), ATM, spans about 150~kb of genomic DNA and is composed of 62 coding exons. ATM mutations are found along the entire coding sequence of the gene, without evidence of mutational hot spots. Using DNA as the starting material, we used denaturing high performance liquid chromatography (DHPLC) technique to search for ATM gene mutations. Initially, DHPLC was validated in a retrospective study of 16 positive control samples that included 19 known mutations; 100% of mutations were detected. Subsequently, DHPLC was used to screen for mutations a cohort of 22 patients with the classical form of A-T. A total of 27 different mutations were identified on 38 of the 44 alleles, corresponding to a 86% detection rate. Fourteen of the mutations were novel. In addition, 15 different variants and polymorphisms of unknown functional significance were found. The high incidence of new and individual A-T mutations in our cohort of patients demonstrates marked mutational heterogeneity of A-T in Italy and corroborate the efficiency of DHPLC as a method for the mutation screening of A-T patients. [ABSTRACT FROM AUTHOR]