Late-onset ataxia telangiectasia

Atypical Ataxia Presentation in Variant Ataxia Telangiectasia: Iranian Case-Series and Review of the Literature

Ataxia-telangiectasia (AT) is a rare autosomal recessive neurodegenerative multisystem disorder. A minority of AT patients can present late-onset atypical presentations due to unknown mechanisms. The demographic, clinical, immunological and genetic data were collected by direct interview and examining the Iranian AT patients with late-onset manifestations. We also conducted a systematic literature review for reported atypical AT patients. We identified three Iranian AT patients (3/249, 1.2% of total registry) with later age at ataxia onset and slower neurologic progression despite elevated alpha-fetoprotein levels, history of respiratory infections, and immunological features of the syndrome. Of note, all patients developed autoimmunity in which a decrease of naïve T cells and regulatory T cells were observed. The literature searches also summarized data from 73 variant AT patients with atypical presentation indicating biallelic mild mutations mainly lead to an atypical phenotype with an increased risk of cancer. Variant AT patients present with milder phenotype or atypical form of classical symptoms causing under- or mis- diagnosis. Although missense mutations are more frequent, an atypical presentation can be associated with deleterious mutations due to unknown modifying factors.

TREC/KREC levels in children with ataxia-telangiectasia

The aim of the study was to determine the TREC/KREC levels in the patients diagnosed with ataxia-telangiectasia (AT) and to establish their informative value for early diagnosis of this pathology. TRECs and KREC assay was performed using real-time polymerase chain reaction on the DNA of 25 patients diagnosed with AT aged 3 to 14 years and of 173 healthy individuals of the control group aged 1 to 12 years. Clinical and laboratory characteristics of patients were ascertained using their medical records. In the patients with AT, the mean level of TRECs was 542.84 per 10⁶ cells, ranging from 4 to 4720, while mean level of KRECs was 1317.64 per 10⁶ cells, ranging from 146 to 9300. In 84% of the patients, TREC levels were less than 1000, which was significantly lower than in the control group, while KREC levels were reduced in 48% of the patients. A correlation was found between the levels of TREC and the absolute values of CD4 (r = 0.5455). Measurement of TREC/KREC levels opens new opportunities for early AT detection in children as a part of the newborn screening. Reduced time to diagnosis will allow to carry out timely in-depth immunological and genetic testing, prevent the development of severe infections, and improve quality of life.

Genetic predisposition to lymphomas: Overview of rare syndromes and inherited familial variants

Approximately 10 % of malignancies occur in carriers of germline mutations predisposing to cancer. A high risk of developing lymphomas has been noted in many primary immunodeficiencies, including DNA repair disorders. Moreover, implementation of next-generation sequencing has recently enabled to uncover rare genetic variants predisposing patients to lymphoid neoplasms. Some patients harboring inherited predisposition to lymphomas require dedicated clinical management, which will contribute to effective cancer treatment and to the prevention of potential severe toxicities and secondary malignancies. In line with that, our review summarizes the natural history of lymphoid tumors developing on different germline genetic backgrounds and discusses the progress that has been made toward successfully treating these malignancies.

Trajectories of motor abnormalities in milder phenotypes of ataxia telangiectasia

OBJECTIVE

To describe and classify the neurologic trajectories in patients with mild neurologic forms of ataxia telangiectasia (A-T) from the Dutch A-T cohort, combined with patients reported in the literature.

METHODS

Clinical, genetic, and laboratory data of 14 patients with mild neurologic phenotypes of A-T from the Dutch cohort were analyzed and combined with corresponding data from the literature. A mild neurologic phenotype was defined by a later onset, nonataxia presenting or dominant feature, or slower progression compared to the classic A-T phenotype. Neurologic trajectories were classified based on age at onset, presenting feature, and follow-up data.

RESULTS

One hundred five patients were included in the study. Neurologic trajectories were categorized into 6 groups: patients with childhood-onset extrapyramidal (EP) features with cerebellar symptoms developing later (group 1; 18 patients), childhood-onset cerebellar symptoms, with EP features developing later (group 2; 35 patients), childhood- to adolescence-onset dystonia, without cerebellar symptoms (group 3; 23 patients), childhood- to adolescence-onset isolated cerebellar symptoms (group 4; 22 patients), childhood- to adult-onset prominent muscle weakness (group 5; 2 patients), and patients with adult-onset EP features, with anterior horn cell disease arising subsequently (group 6; 5 patients).

CONCLUSIONS

This systematic study of the different motor abnormalities and their course over time in patients with mild phenotypes of A-T, enabled us to recognize 6 essentially different phenotypic patterns. Awareness of these different trajectories of motor abnormalities in milder forms of A-T will contribute to a reduction of diagnostic delay in this severe multisystem disorder.