[Ataxia-telangiectasia: a review]

Primary Immunodeficiency-Type Ataxia-Telangiectasia Revealed by Splenic Abscesses

Ataxia-telangiectasia (A-T) is a rare inherited autosomal recessive disease. It is associated with an alteration in the ATM gene, located on chromosome 11q22-23, which codes for a protein involved in a complex way in cell cycle regulation and cell protection. It is characterized by cerebellar ataxia, cutaneous and ocular telangiectasia, and an immune deficiency responsible for recurrent infections. Diagnosis is generally delayed due to the late onset of neurological symptoms and telangiectasia. People suffering from this condition are particularly sensitive to ionizing radiation, which considerably increases their risk of developing neoplasia. We report an observation of a primary immunodeficiency-type A-T revealed by recurrent fever and multiple splenic abscesses.

Two novel variants in the ATM gene causing ataxia-telangiectasia, including a duplication of 90 kb: Utility of targeted next-generation sequencing in detection of copy number variation

Ataxia-telangiectasia (A-T) is a rare autosomal recessive neurodegenerative disorder characterized by progressive cerebellar ataxia, ocular apraxia, immunodeficiency, telangiectasia, elevated serum α-fetoprotein concentration, radiosensitivity and cancer predisposition. Classical A-T is caused by biallelic variants on ATM (ataxia telangiectasia mutated) gene, leading to a loss of function of the protein kinase ATM, involved in DNA damage repair. Atypical presentations can be found in A-T-like disease or in Nijmegen breakage syndrome, caused by deficiency of mre11 or nibrin proteins, respectively. In this report, we present the genetic characterization of a 4-year-old female with clinical diagnosis of A-T. Next-generation sequencing (NGS) revealed two novel heterozygous mutations in the ATM gene: a single-nucleotide variant (SNV) at exon 47 (NM_000051.3:c.6899G > C; p.Trp2300Ser) and ∼90 kb genomic duplication spanning exons 17-61, NG_009830.1:g.(41245_49339)_(137044_147250)dup. These findings were validated by Sanger sequencing and MLPA (multiplex ligation-dependent probe amplification) analysis respectively. Familial segregation study confirmed that the two variants are inherited, and the infant is a compound heterozygote. Thus, our study expands the spectrum of ATM pathogenic variants and demonstrates the utility of targeted NGS in the detection of copy number variation.

B-cell subsets imbalance and reduced expression of CD40 in ataxia-telangiectasia patients

BACKGROUND

Ataxia-telangiectasia (AT) is a well-known primary immunodeficiency with recurrent sinopulmonary infections and variable abnormalities in both the humoral and cellular immune system. Dysfunctions in immunoglobulin production, reduced number of B cells, and B-cell receptor excision circles copies have been reported. We aimed to understand the immunological mechanisms involving the humoral compartment in AT patients by analysing peripheral blood B cells subsets, B-T lymphocyte cooperation through the expression of CD40 and CD40 ligand (CD40L), and cytokines involved in class-switch recombination production.

METHODS

We compared the proportion of B-cell subsets, the expression of CD40/CD40L, and the plasma levels of IL-6 and IFN-γ of 18 AT patients and 15 healthy age-sex-matched controls using flow cytometry.

RESULTS

We found that some steps in peripheral B cell development were altered in AT with a pronounced reduction of cell-surface CD40 expression. The proportions of transitional and naïve-mature B cells were reduced, whereas CD21-low, natural effector memory, IgM-only memory, and IgG atypical memory B cells were present in a higher proportion.

CONCLUSIONS

These findings revealed a disturbed B-cell homeostasis with unconventional maturation of B lymphocyte memory cells, which can explain the consequent impairment of humoral immunity.

Ataxia-telangiectasia - A historical review and a proposal for a new designation: ATM syndrome

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.

Ataxia-telangiectasia and wilms tumor: reduced treatment but early relapse

Ataxia-telangiectasia (A-T) is an autosomal recessive disease characterized by progressive cerebellar ataxia, oculocutaneous telangiectasia, immunodeficiency, a high incidence of lymphoreticular tumors, and an increased sensitivity to chemoradiotherapy-induced DNA damage. The appropriate cancer therapy remains unknown because of high toxicity rates with full-dose conventional protocols. We present a patient with A-T and nephroblastoma, who received an adapted treatment regimen. To our knowledge this is the second report on nephroblastoma in a patient with A-T but the first with confirmed premortem studies. Although the patient tolerated the chemotherapy regimen well, the patient relapsed and died a year after initial diagnosis.

Peripheral nerve involvement in hereditary cerebellar and multisystem degenerative disorders

Hereditary ataxias (HA) encompass an increasing number of degenerative disorders characterized by progressive cerebellar ataxia usually accompanied by extracerebellar semeiology including peripheral nerve involvement. Classically, HA were classified according to their pathological hallmark comprising three main forms: (1) spinal form predominantly with degeneration of spinocerebellar tracts, posterior columns, and pyramidal tracts (Friedreich's ataxia, FA); (2) olivopontocerebellar atrophy (OPCA); and (3) cortical cerebellar atrophy (CCA). In the 1980s Harding proposed a clinico-genetic classification based upon age of onset, modality of transmission, and clinical semeiology. The main categories in this classification were as follows: (1) early onset cerebellar ataxia (EOCA) with age of onset below 25 years and usually with autosomal recessive (AR) transmission (this group encompasses FA and syndromes different from FA); (2) autosomal dominant cerebellar ataxia (ADCA) with adult onset and with either cerebellar-plus syndrome or pure cerebellar semeiology; and (3) idiopathic late onset onset cerebellar ataxia (ILOCA). With the advent of molecular genetics, the nosology of HA has been in a state of constant flux. At present EOCA comprises at least 17 genotypes (designated with the acronym of ARCA derived from AR cerebellar ataxia), whereas under the umbrella of ADCA 30 genotypes have been reported. In this chapter we will review peripheral nerve involvement in classical pathological entities (OPCA and CCA), ARCA, ADCA, and ILOCA paying special attention to the most prevalent syndromes in each category. As a general rule, nerve involvement is relatively common in any form of ataxia except ILOCA, the most common pattern being either sensory or sensorimotor neuronopathy with a dying-back process. An exception to this rule is AR spastic ataxia of Charlevoix-Saguenay where nerve conduction studies show the characteristic pattern of intermediate neuropathy implying that sacsin mutation causes both axonal and Schwann cell dysfunction.

Neurocutaneous syndrome: a prospective study

BACKGROUND

Neurocutaneous syndromes (NCS) are a group of genetic disorders that produce a variety of developmental abnormalities of the skin along with an increased risk of neurological complications. Cutaneous manifestations usually appear early in life and progress with time, but neurological features generally present at a later age. There is a paucity of data regarding the evolution of skin lesions and their correlation with the central nervous system involvement in children.

AIM

The primary objective was to track the course of skin lesions in various forms of NCS in the pediatric age group. Our secondary aim was to assess whether there was any predictive value of the lesions in relation to the neurological manifestations.

MATERIALS AND METHODS

This prospective longitudinal study was conducted at a tertiary care pediatric dermatology referral clinic of the Institute of Child Health, Kolkata, West Bengal. Children between the age group 0 and 12 years were included in the study on the basis of standard diagnostic criteria for different NCS, during the period from March, 2000 to February, 2004, and each of the enrolled cases were followed up for a duration of six years.

RESULTS

The study population comprised of 67 children (35 boys, 32 girls).The mean age of presentation was 33.8±27.8 months (range 10 days to 111 months). The various forms of NCS observed was neurofibromatosis 1(NF1) (n=33), tuberous sclerosis complex (TSC) (n=23), Sturge Weber syndrome (n=6), ataxia telangiectasia (n=2), PHACE syndrome (n=1), incontinentia pigmenti (n=1), and hypomelanosis of Ito (n=1). The presentations were varied, ranging from predominantly cutaneous to primarily neurological, depending on the disease entity and age group concerned. There was a significant increase in the number of café au lait macules (CALMs) with time (P=0.0002) in NF1, unlike that of hypopigmented macules of TSC (P=0.15). Statistically, no relation was documented between the evolution of skin lesions and neurological manifestations in the major groups.

CONCLUSION

As NCS is not an uncommon disease in children, it is always necessary to find out the subtle neurological signs, whenever we observe any case with cutaneous markers suggestive of NCS. In addition, it is a must to do a detailed dermatological examination in a child with central nervous system involvement, in the pediatric population. However, the neurological course cannot be predicted from skin lesions.

[Anesthetic considerations in primary immunodeficiencies]

Primary immunodeficiencies are a group of mostly hereditary, or congenital, disorders. Some cases, however, show no hereditary pattern despite an evident familial distribution. The incidence of these cases is variable and the most frequent of them is immunoglobulin A deficiency. Many are pediatric disorders that are occasionally so serious that the patient does not survive the first year of life due to the development of systemic infections. In other cases, survival is much longer and it is possible to find adult carriers in routine clinical practice. These are less aggressive cases that form part of specific clinical syndromes that must be recognized so that appropriate anesthetic management can be planned. We review the clinical characteristics of primary immunodeficiencies that may be relevant to anesthetic management in these patients.

LKB1 and AMPK in cell polarity and division

LKB1 and AMP-activated protein kinase (AMPK) are serine-threonine kinases implicated in key cellular pathways, including polarity establishment and energy sensing, respectively. Recent in vivo analyses in Drosophila have demonstrated vital roles for both AMPK and LKB1--in part through the myosin regulatory light chain--in cell polarity and cell division. Evidence from mammalian experiments also supports non-metabolic functions for LKB1 and AMPK. This review examines unanticipated AMPK functions for initiating and maintaining cell polarity and completing normal cell division. The ability of AMPK to sense energy status might be coupled with fundamental cell biological functions.

T-cell acute lymphoblastic leukemia in a child with ataxia-telangiectasia: case report

We present a patient with acute lymphoblastic leukemia and ataxia-telangiectasia (A-T). The 4-year-old girl is the first child of young nonconsanguineous parents of Serbian origin. Gait problems appearing in the second year of life were treated by physiotherapy. At the age of 4 she was diagnosed with T-cell acute lymphoblastic leukemia and treated according to Berlin-Frankfurt-Munster strategy. Owing to typhlitis developing after 15 days of cytotoxic treatment, frequent radiologic examinations were performed causing profound aplasia. Typhlitis did not respond to conservative treatment but necessitated extensive bowel resection. At that time the A-T was suspected by our team and confirmed by increased chromosomal radiosensitivity and markedly reduced level of A-T mutated protein. Chemotherapy was continued without alkylating agents and further radiologic imaging ran an uncomplicated course. At present, the patient is in first remission and 2.5 years since the beginning of the treatment. We stress the importance of careful initial neurologic evaluation of children with malignancy.

Lung disease in ataxia-telangiectasia

Ataxia-telangiectasia (AT) is a multi-systemic disease caused by mutational inactivation of the ATM gene. We report a retrospective study of lung disease in 15 patients.

PATIENTS AND METHODS

A diagnosis of AT was made if the patient met the following criteria: neurological features and at least one the following: oculo-cutaneous telangiectasia, elevated serum alpha-feto-protein level.

RESULTS

Recurrent sino-pulmonary infections were usually present in 11 of the cases and occurred during the first 2 years of life. Other lung injuries noted were bronchiectasis, obstruction and restriction of the airways, fibrosis, pneumothorax and haemoptysis. Eleven children had immunodeficiencies.

DISCUSSION

Recurrent sino-pulmonary manifestations precede neurological complications, but the severity of neuro-degeneration and pulmonary disease were not correlated. Pulmonary status was a prognosis factor. Immunodeficiency was the main, but not the only, aetiology for lung disease in AT.

CONCLUSION

There is little dispute over the role of ATM in lung and respiratory epithelium. To reduce the morbidity associated with AT, there needs to be greater awareness of respiratory complications. Early management and monitoring lung function is necessary to minimize lung damage.