Molecular defects in Moroccan patients with ataxia-telangiectasia

Clinical and genetic spectrum of Ataxia Telangiectasia Tunisian patients: Bioinformatic analysis unveil mechanisms of ATM variants pathogenicity

Ataxia Telangiectasia (AT) is a rare multisystemic neurodegenerative disease caused by biallelic mutations in the ATM gene. Few clinical studies on AT disease have been conducted in Tunisia, however, the mutational landscape is still undefined. Our aim is to determine the clinical and genetic spectrum of AT Tunisian patients and to explore the potential underlying mechanism of variant pathogenicity. Sanger sequencing was performed for nine AT patients. A comprehensive computational analysis was conducted to evaluate the possible pathogenic effect of ATM identified variants. Genetic screening of ATM gene has identified nine different variants from which six have not been previously reported. In silico analysis have predicted a pathogenic effect of identified mutations. This was corroborated by a structural bioinformatics study based on molecular modeling and docking for novel missense mutations. Our findings suggest a profound impact of identified mutations not only on the ATM protein stability, but also on the ATM-ligand interactions. Our study characterizes the mutational landscape of AT Tunisian patients which will allow to set up genetic counseling and prenatal diagnosis for families at risk and expand the spectrum of ATM variants worldwide. Furthermore, understanding the mechanism that underpin variant pathogenicity could provide further insights into disease pathogenesis.

Novel ATM Gene c.5644 C > T (p.Arg1882*) Variant Detected in a Patient with Pancreatic Adenocarcinoma and Two Primary Non-Small Cell Lung Adenocarcinomas: A Case Report

Ataxia-telangiectasia is an autosomal recessive disorder that usually manifests in childhood due to mutations in the Ataxia-Telangiectasia Mutated (ATM) gene. It is believed that there is an association between this gene mutation/polymorphism and cancer risk, including breast, lung, and pancreatic cancers. We report a rare case of a 69-year-old woman who developed three different primary cancers, including non-small cell lung cancer (NSCLC) in both lungs and pancreatic adenocarcinoma, and was later found to have a rarely reported variant mutation in the ATM gene, namely Exon 39, c.5644 C > T. We hypothesize that the ATM gene, c.5644 C > T mutation could be a plausible contributor in the pathogenesis of these three cancers. This hypothesis has yet to be validated by larger studies that focus on a mechanistic approach involving DNA repair genes such as the ATM. More importantly, this paves the way to developing new patient-specific targeted therapies and inaugurating precision medicine as a cornerstone in cancer therapeutics.

Consensus Recommendations for the Clinical Management of Hematological Malignancies in Patients with DNA Double Stranded Break Disorders

Patients with double stranded DNA repair disorders (DNARDs) (Ataxia Telangiectasia (AT) and Nijmegen Breakage syndrome (NBS)) are at a very high risk for developing hematological malignancies in the first two decades of life. The most common neoplasms are T-cell lymphoblastic malignancies (T-cell ALL and T-cell LBL) and diffuse large B cell lymphoma (DLBCL). Treatment of these patients is challenging due to severe complications of the repair disorder itself (e.g., congenital defects, progressive movement disorders, immunological disturbances and progressive lung disease) and excessive toxicity resulting from chemotherapeutic treatment. Frequent complications during treatment for malignancies are deterioration of pre-existing lung disease, neurological complications, severe mucositis, life threating infections and feeding difficulties leading to significant malnutrition. These complications make modifications to commonly used treatment protocols necessary in almost all patients. Considering the rarity of DNARDs it is difficult for individual physicians to obtain sufficient experience in treating these vulnerable patients. Therefore, a team of experts assembled all available knowledge and translated this information into best available evidence-based treatment recommendations.

The natural history of ataxia-telangiectasia (A-T): A systematic review

BACKGROUND

Ataxia-telangiectasia is an autosomal recessive, multi-system, and life-shortening disease caused by mutations in the ataxia-telangiectasia mutated gene. Although widely reported, there are no studies that give a comprehensive picture of this intriguing condition.

OBJECTIVES

Understand the natural history of ataxia-telangiectasia (A-T), as reported in scientific literature.

SEARCH METHODS

107 search terms were identified and divided into 17 searches. Each search was performed in PubMed, Ovid SP (MEDLINE) 1946-present, OVID EMBASE 1980 -present, Web of Science core collection, Elsevier Scopus, and Cochrane Library.

SELECTION CRITERIA

All human studies that report any aspect of A-T.

DATA COLLECTION AND ANALYSIS

Search results were de-duplicated, data extracted (including author, publication year, country of origin, study design, population, participant characteristics, and clinical features). Quality of case-control and cohort studies was assessed by the Newcastle-Ottawa tool. Findings are reported descriptively and where possible data collated to report median (interquartile range, range) of outcomes of interest.

MAIN RESULTS

1314 cases reported 2134 presenting symptoms. The most common presenting symptom was abnormal gait (1160 cases; 188 studies) followed by recurrent infections in classical ataxia-telangiectasia and movement disorders in variant ataxia-telangiectasia. 687 cases reported 752 causes of death among which malignancy was the most frequently reported cause. Median (IQR, range) age of death (n = 294) was 14 years 0 months (10 years 0 months to 23 years 3 months, 1 year 3 months to 76 years 0 months).

CONCLUSIONS

This review demonstrates the multi-system involvement in A-T, confirms that neurological symptoms are the most frequent presenting features in classical A-T but variants have diverse manifestations. We found that most individuals with A-T have life limited to teenage or early adulthood. Predominance of case reports, and case series demonstrate the lack of robust evidence to determine the natural history of A-T. We recommend population-based studies to fill this evidence gap.

Ataxia-telangiectasia with a novel ATM gene mutation and Burkitt leukemia: A case report

Ataxia-telangiectasia (A-T) is an infrequent autosomal recessive disorder that involves multiple systems and is characterized by progressive cerebellar ataxia, oculocutaneous telangiectasias, radiosensitivity, immune deficiency with recurrent respiratory infections, and a tendency to develop lymphoid malignancies. A-T is caused by mutations in the ATM gene, with >1,000 mutations reported to date and gradually increasing in number. Patients with A-T have an increased incidence of cancers. The aim of the present study was to retrospectively review the case of a patient who presented at the age of 5 years with cerebellar ataxia without telangiectasia, and was diagnosed with Burkitt leukemia by bone marrow biopsy and molecular testing at the age of 7 years at the Xiangya Hospital of Central South University (Changsha, China). The patient received chemotherapy with the pediatric CCCG-BNHL-2015 regimen (R4 group) and achieved a complete remission after 2 courses. However, recurrent respiratory infections and thrombosis occurred during chemotherapy. The diagnosis of A-T was confirmed by uncovering two variants of the ATM gene, including c.742C>T (p.R248X; rs730881336) in exon 7 and c.6067-c.6068 ins GAGGGAAGAT in exon 41 by whole-exome sequencing. Unfortunately, the patient's parents refused follow-up treatment and he succumbed to recurrent severe infections 4 months after the diagnosis of Burkitt leukemia. The diagnosis of A-T may be challenging, as its phenotype can be incomplete early in the course of the disease. Detailed medical history, characteristic clinical manifestations and increasingly developed exome sequencing techniques may be helpful in diagnosing this rare disease. Management should be based on multidisciplinary guidance and other treatment options must be investigated in the future.

A portrait of germline mutation in Brazilian at-risk for hereditary breast cancer

PURPOSE

Knowledge about the germline mutational spectrum among Brazilian with hereditary breast and ovarian cancer (HBOC) is limited. Only five studies have performed comprehensive BRCA sequencing, corresponding to 1041 individuals among a Brazilian population of over 207 million people. Herein we aimed to determine the clinical and molecular characteristics of Brazilian patients who underwent oncogenetic counseling and genetic testing of a panel of high-risk and moderate-risk genes from 2009 to 2017.

METHODS

Massively parallel sequencing was applied in 157 individuals (132 breast cancer-affected and 25 breast cancer-unaffected individuals) selected according NCCN criteria for hereditary breast cancer. Analysis of mutation segregation in family members was performed by capillary bidirectional sequencing, clinical response after treament and survival analysis was estimated by Kaplan-Meier.

RESULTS

Nineteen germline variants were identified,15 pathogenic and 4 VUS (Variants of Uncertain Significance) in 27 individuals (27/157; 17% P < 0.0001) distributed among 7 genes. Sixty-eight percent of patients (13/19) harbor mutation in BRCA genes and 32% (6/19) in moderate risk genes. This is the first study reporting ATR deleterious germline mutation in association with hereditary breast cancer. Cancer-affected patients with moderate- risk mutation present a more aggressive phenotype, with bilateral cancer (25% vs. 13%, P = 0.0305), high-grade tumors (79.2% vs. 46.3%, P = 0.0001) and triple-negative (50% vs. 22.4%, P < 0.0001). However, no difference in the 5 years overall survival was observed between BRCA and moderate risk groups.

CONCLUSIONS

This work highlights the benefits of large-scale sequencing for oncogenetic counseling and extends our understanding about the genetics of hereditary breast cancer in the multi-ethnic Brazilian population.

Neurogenomics in Africa: Perspectives, progress, possibilities and priorities

The understanding of the genetic basis of neurological disorders has grown rapidly in the last two decades. Despite the genomic heterogeneity within African populations, large-scale candidate gene or linkage and exome studies are lacking. However, current knowledge on neurogenetics in African populations is limited and geographically very uneven. Isolated reports indicate the existence of autosomal dominant or recessive conditions incorporating cerebrovascular, movement, neuromuscular, seizure and motor neuron disorders in Africans. In addition, few African families with neurodegenerative disorders associated with dementia have been characterized in North, West and South Africa. The current insurgency in genomic research triggered by among others the Human Health and Heredity (H3) Africa Initiative indicates that there are unique opportunities to advance our knowledge and understanding of the influence of genomic variation on the pattern, presentations and prognosis of neurological disorders in Africa. These have enormous potential to unmask novel genes and molecular pathways germane to the neurobiology of brain disorders. It would facilitate the development of novel diagnostics, preventative and targeted treatments in the new paradigm of precision medicine. Nevertheless, it is crucial to strike a balance between effective traditional public health strategies and personalized genome based care. The translational barriers can be overcome through robust stakeholder engagement and sustainable multilevel, multigenerational and multidisciplinary capacity building and infrastructural development for genomic medicine in Africa.

First report on the Moroccan registry of primary immunodeficiencies: 15 years of experience (1998-2012)

PURPOSE

Primary immunodeficiencies (PIDs) are a large group of diseases characterized by susceptibility to infections. We provide the first comprehensive report on PIDs in Morocco, the epidemiological, clinical, etiological and outcome features which have never before been described.

METHODS

A national registry was established in 2008, grouping together data for PID patients diagnosed since 1998.

RESULTS

In total, 421 patients were diagnosed between 1998 and 2012. Parental consanguinity was common (recorded for 43.2 % of patients) and the median time to diagnosis was 2.0 years. Overall, 27.4 % of patients were considered to have well defined syndromes with immunodeficiency (48 cases of hyper-IgE syndrome and 40 of ataxia-telangiectasia); 22.7 % had predominantly antibody deficiencies (29 cases of agammaglobulinemia and 24 of CVID); 20.6 % had combined immunodeficiencies (37 cases of SCID and 26 of MHC II deficiencies) and 17.5 % had phagocyte disorders (14 cases of SCN and 10 of CGD). The principal clinical signs were lower respiratory tract infections (60.8 %), skin infections (33.5 %) and candidiasis (26.1 %). Mortality reached 28.8 %, and only ten patients underwent bone marrow transplantation. We analyzed the impact on mortality of residence, family history, parental consanguinity, date of diagnosis and time to diagnosis, but only date of diagnosis had a significant effect.

CONCLUSIONS

The observed prevalence of PID was 0.81/100,000 inhabitants, suggesting considerable underdiagnosis and a need to increase awareness of these conditions in Morocco. The distribution of PIDs was different from that reported in Western countries, with a particularly high proportion of SCID, MHC II deficiencies, hyper-IgE syndrome and autosomal recessive agammaglobulinemia. However, we have now organized a national network, which should improve diagnosis rates in remote regions.