Classic ataxia-telangiectasia: the phenotype of long-term survivors

Nerve Ultrasound Detects Nerve Atrophy in Patients With Ataxia-Telangiectasia: A Pilot Study

INTRODUCTION/AIMS

Ataxia-telangiectasia (A-T) is a genetic multisystem neurodegenerative disorder characterized by cerebellar ataxia, oculocutaneous telangiectasia, extrapyramidal involvement, peripheral sensorimotor neuropathy, immunodeficiency, pulmonary disease, and an increased risk of malignancy that ultimately determines the shortened lifespan in many patients. A-T nerve ultrasonographic characteristics remain underexplored. This pilot study aimed to characterize the ultrasonographic morphology of peripheral nerves in patients with A-T.

METHODS

Ultrasound cross-sectional areas (CSAs) of the median, ulnar, sural, and tibial nerves were obtained from three A-T patients and were compared to reference values. Nerve conduction studies and electromyography were also performed. Given the small sample size and the exploratory nature of this study, formal statistical analyses were not performed, and descriptive statistics were presented for the data.

RESULTS

Nerve CSAs in A-T patients were smaller than in healthy controls at all measurement sites.

DISCUSSION

Nerve ultrasound revealed atrophy in the peripheral nerves of A-T patients. This reduction in nerve size may distinguish A-T and highlights the utility of nerve ultrasound as a non-invasive diagnostic tool for peripheral sensorimotor neuropathy. These findings may have important implications for early detection in clinical practice.

Autosomal Recessive Ataxias in Northeast Brazil: A Regional Multicenter Case Series

Hereditary cerebellar ataxias are a diverse group of neurodegenerative disorders characterized by progressive cerebellar dysfunction and possible multisystemic involvement. While significant advancements have been made in understanding autosomal dominant cerebellar ataxias (ADCAs), autosomal recessive cerebellar ataxias (ARCAs) remain less extensively investigated than autosomal dominant ataxias, particularly in regions with high consanguinity. This study aimed to characterize 57 patients with ARCAs in Ceará, northeast Brazil. We analyzed 57 patients diagnosed with ARCAs caused by biallelic variants in ARCA-associated genes. Patients underwent clinical evaluations, including neurological examinations and functional assessments.

RESULTS

Friedreich's ataxia (FRDA) was the most prevalent diagnosis, accounting for 12 cases (21%), followed by Ataxia-Telangiectasia (A-T) with (N = 9; 15.8%) and Niemann-Pick Disease Type C (NPC) (N = 9; 15.8%). Metabolic disorders, including Cerebrotendinous Xanthomatosis (N = 6;10.5%) were also common causes. The cohort demonstrated a broad age distribution, with childhood-onset conditions such as A-T predominantly affecting younger patients. In contrast, adult-onset conditions like FRDA and NPC were more common in those aged 18 years and older.

DISCUSSION

This study highlights the heterogeneity of ARCAs in a region with high consanguinity, reflecting these disorders' diverse genetic and clinical spectrum.

CONCLUSION

The clinical and genetic characterization of ARCAs presented in this case series emphasizes the importance of early diagnosis, genetic confirmation, and targeted management strategies. Our findings highlight the need for continued research and expanded diagnostic programs, particularly in regions with high consanguinity, to improve patient outcomes and advance therapeutic development.

Ataxia telangiectasia

Ataxia telangiectasia (AT) is a rare neurocutaneous syndrome that results from biallelic pathogenic variants in the ataxia telangiectasia mutated (ATM) gene, named for its characteristic cerebellar ataxia in the early toddler years and variable oculocutaneous telangiectasias in the school age years. While its name only hints at neurologic and cutaneous manifestations, this multisystemic disorder also has important immunologic, oncologic, respiratory, and endocrinologic implications. This article will review the function of the ATM gene, the neurologic manifestations of AT, non-neurologic complications, mimickers of AT (including other disorders of defective DNA repair), and the realm of therapeutic research for AT.

Genetic Characteristics of a Large Pediatric Cohort of Patients with Inborn Errors of Immunity: Single-Center Experience

More than 450 genetic defects result in inborn errors of immunity (IEI). Their individual prevalence in specific cohorts is influenced by national characteristics and other factors. We present results of genetic testing conducted in 1809 Russian children with IEI. Genetic defects confirming IEI were found in 1112 out of 1809 (61.5%) probands. These defects included variants in 118 single genes (87.9% of patients) and aberrations in 6 chromosomes (11.8%). Notably, three patients harbored pathogenic variants in more than one IEI gene. Large deletions constituted 5% of all defects. Out of the 799 original variants, 350 (44%) have not been described previously. Rare genetic defects (10 or fewer patients per gene) were identified in 20% of the patients. Among 967 probands with germline variants, defects were inherited in an autosomal dominant manner in 29%, X-linked in 34%, and autosomal recessive in 37%. Four females with non-random X-inactivation exhibited symptoms of X-linked diseases (BTK, WAS, CYBB, IKBKG gene defects). Despite a relatively low rate of consanguinity in Russia, 47.9% of autosomal recessive gene defects were found in a homozygous state. Notably, 28% of these cases carried "Slavic" mutation of the NBN gene or known hot-spot mutations in other genes. The diversity of IEI genetic forms and the high frequency of newly described variants underscore the genetic heterogeneity within the Russian IEI group. The new variants identified in this extensive cohort will enrich genetic databases.

Neurocutaneous Diseases: Diagnosis, Management, and Treatment

Neurocutaneous disorders, also known as phakomatoses, are congenital and acquired syndromes resulting in simultaneous neurologic and cutaneous involvement. In several of these conditions, the genetic phenomenon is understood, providing a pivotal role in the development of therapeutic options. This review encompasses the discussion of the genetic and clinical involvement of neurocutaneous disorders, and examines clinical management and treatment options. With the current advances in genetics, the role of precision medicine and targeted therapy play a substantial role in addressing the management of these conditions. The interconnectedness between therapeutic options highlights the importance of precision medicine in treating each disorder's unique molecular pathway. This review provides an extensive synthesis of ongoing and current therapeutics in the management of such clinically unique and challenging conditions.

Patient-Reported Outcomes and Medical Provider Satisfaction Among Adult and Pediatric Ataxia-Telangiectasia Patients

PURPOSE

Ataxia-telangiectasia (A-T) is a rare genetic condition with malfunctioning DNA repair processes resulting in significant clinical findings, including progressive neurologic decline, elevated malignancy risk, immunodeficiency, oculocutaneous telangiectasias, and severe pulmonary disease. Research has been limited into the quality of life of such patients and yet to be completed are studies quantitatively analyzing psychosocial, physical, and cognitive patient-reported outcomes (PROs) within the A-T population.

METHODS

PRO evaluations of 90 international adult and pediatric A-T patients and their caregivers were completed via secure online administration of Patient-Reported Outcomes Measurement Information System (PROMIS) short forms evaluating anger, cognition, mood, social health, fatigue, pain, anxiety, and upper extremity function. The impact of age, gender, race/ethnicity, prior malignancy diagnosis, and current supportive treatment interventions on such PROs was additionally assessed. Finally, given the importance of medical providers in the care of A-T patients and the impact of patient satisfaction on healthcare outcomes, we further analyzed, via a novel survey, how patients and caregivers perceived their primary A-T healthcare provider's A-T expertise, trustworthiness, accessibility, and level of compassion.

RESULTS/CONCLUSION

It was found that a diagnosis of A-T complexly impacts patient PROs, but such data offers the potential for preventative and therapeutic interventions to improve the care of such patients. While most A-T patients and their caregivers feel their primary A-T medical provider has expertise and compassion in addition to being accessible and trustworthy, a significant percentage of study subjects did not agree that their provider was an expert in A-T or overall trustworthy.

New Views of the DNA Repair Protein Ataxia-Telangiectasia Mutated in Central Neurons: Contribution in Synaptic Dysfunctions of Neurodevelopmental and Neurodegenerative Diseases

Ataxia-Telangiectasia Mutated (ATM) is a serine/threonine protein kinase principally known to orchestrate DNA repair processes upon DNA double-strand breaks (DSBs). Mutations in the Atm gene lead to Ataxia-Telangiectasia (AT), a recessive disorder characterized by ataxic movements consequent to cerebellar atrophy or dysfunction, along with immune alterations, genomic instability, and predisposition to cancer. AT patients show variable phenotypes ranging from neurologic abnormalities and cognitive impairments to more recently described neuropsychiatric features pointing to symptoms hardly ascribable to the canonical functions of ATM in DNA damage response (DDR). Indeed, evidence suggests that cognitive abilities rely on the proper functioning of DSB machinery and specific synaptic changes in central neurons of ATM-deficient mice unveiled unexpected roles of ATM at the synapse. Thus, in the present review, upon a brief recall of DNA damage responses, we focus our attention on the role of ATM in neuronal physiology and pathology and we discuss recent findings showing structural and functional changes in hippocampal and cortical synapses of AT mouse models. Collectively, a deeper knowledge of ATM-dependent mechanisms in neurons is necessary not only for a better comprehension of AT neurological phenotypes, but also for a higher understanding of the pathological mechanisms in neurodevelopmental and degenerative disorders involving ATM dysfunctions.

Somatic and germline ATM variants in non-small-cell lung cancer: Therapeutic implications

ATM is an apical kinase of the DNA damage response involved in the repair of DNA double-strand breaks. Germline ATM variants (gATM) have been associated with an increased risk of developing lung adenocarcinoma (LUAD), and approximately 9% of LUAD tumors harbor somatic ATM mutations (sATM). Biallelic carriers of pathogenic gATM exhibit a plethora of immunological abnormalities, but few studies have evaluated the contribution of immune dysfunction to lung cancer susceptibility. Indeed, little is known about the clinicopathological characteristics of lung cancer patients with sATM or gATM alterations. The introduction of targeted therapies and immunotherapies, and the increasing number of clinical trials evaluating treatment combinations, warrants a careful reexamination of the benefits and harms that different therapeutic approaches have had in lung cancer patients with sATM or gATM. This review will discuss the role of ATM in the pathogenesis of lung cancer, highlighting potential therapeutic approaches to manage ATM-deficient lung cancers.

DNA Damage Response-Associated Cell Cycle Re-Entry and Neuronal Senescence in Brain Aging and Alzheimer's Disease

Chronological aging is by far the strongest risk factor for age-related dementia and Alzheimer's disease. Senescent cells accumulated in the aging and Alzheimer's disease brains are now recognized as the keys to describing such an association. Cellular senescence is a classic phenomenon characterized by stable cell arrest, which is thought to be applicable only to dividing cells. Emerging evidence indicates that fully differentiated post-mitotic neurons are also capable of becoming senescent, with roles in contributing to both brain aging and disease pathogenesis. The key question that arises is the identity of the upstream triggers and the molecular mechanisms that underly such changes. Here, we highlight the potential role of persistent DNA damage response as the major driver of senescent phenotypes and discuss the current evidence and molecular mechanisms that connect DNA repair infidelity, cell cycle re-entry and terminal fate decision in committing neuronal cell senescence.

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: epidemiology, pathogenesis, clinical phenotype, diagnosis, prognosis and management

INTRODUCTION

Ataxia-telangiectasia (A-T) is a rare autosomal recessive syndrome characterized by progressive cerebellar ataxia, oculocutaneous telangiectasia, variable immunodeficiency, radiosensitivity, and cancer predisposition. Mutations cause A-T in the ataxia telangiectasia mutated (ATM) gene encoding a serine/threonine-protein kinase.

AREAS COVERED

The authors reviewed the literature on PubMed, Web of Science, and Scopus databases to collect comprehensive data related to A-T. This review aims to discuss various update aspects of A-T, including epidemiology, pathogenesis, clinical manifestations, diagnosis, prognosis, and management.

EXPERT OPINION

A-T as a congenital disorder has phenotypic heterogeneity, and the severity of symptoms in different patients depends on the severity of mutations. This review provides a comprehensive overview of A-T, although some relevant questions about pathogenesis remain unanswered, probably owing to the phenotypic heterogeneity of this monogenic disorder. The presence of various clinical and immunologic manifestations in A-T indicates that the identification of the role of defective ATM in phenotype can be helpful in the better management and treatment of patients in the future.

Consensus of the Italian Primary Immunodeficiency Network on transition management from pediatric to adult care in patients affected with childhood-onset inborn errors of immunity

Medical advances have dramatically improved the long-term prognosis of children and adolescents with inborn errors of immunity (IEIs). Transfer of the medical care of individuals with pediatric IEIs to adult facilities is also a complex task because of the large number of distinct disorders, which requires involvement of patients and both pediatric and adult care providers. To date, there is no consensus on the optimal pathway of the transitional care process and no specific data are available in the literature regarding patients with IEIs. We aimed to develop a consensus statement on the transition process to adult health care services for patients with IEIs. Physicians from major Italian Primary Immunodeficiency Network centers formulated and answered questions after examining the currently published literature on the transition from childhood to adulthood. The authors voted on each recommendation. The most frequent IEIs sharing common main clinical problems requiring full attention during the transitional phase were categorized into different groups of clinically related disorders. For each group of clinically related disorders, physicians from major Italian Primary Immunodeficiency Network institutions focused on selected clinical issues representing the clinical hallmark during early adulthood.

Update on DNA-Double Strand Break Repair Defects in Combined Primary Immunodeficiency

PURPOSE OF REVIEW

The most serious DNA damage, DNA double strand breaks (DNA-dsb), leads to mutagenesis, carcinogenesis or apoptosis if left unrepaired. Non-homologous end joining (NHEJ) is the principle repair pathway employed by mammalian cells to repair DNA-dsb. Several proteins are involved in this pathway, defects in which can lead to human disease. This review updates on the most recent information available for the specific diseases associated with the pathway.

RECENT FINDINGS

A new member of the NHEJ pathway, PAXX, has been identified, although no human disease has been associated with it. The clinical phenotypes of Artemis, DNA ligase 4, Cernunnos-XLF and DNA-PKcs deficiency have been extended. The role of haematopoietic stem cell transplantation, following reduced intensity conditioning chemotherapy, for many of these diseases is being advanced. In the era of newborn screening, urgent genetic diagnosis is necessary to correctly target appropriate treatment for patients with DNA-dsb repair disorders.