Ataxia telangiectasia

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	Ataxia telangiectasia;
ICD-10	G11.3
ICD-9	334.8
OMIM	208900
DiseasesDB	1025
MedlinePlus	001394
MeSH	D001260

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Seyed Arash Javadmoosavi, MD [2] Zaida Obeidat, M.D. For patient information, click here

Synonyms and keywords: Louis-bar syndrome, Boder-sedgwick syndrome.

Overview

Ataxia telangiectasia (A-T)is an autosomal recessive disorder caused by mutations in the gene ATM (ataxia-telangiectasia mutated)(11q22.3). This gene is expressed commonly and encodes a protein kinase (ATM kinase) which plays a key role in the control of double-strand-break DNA repair. A-T is a progressive, multisystem disease that has a large number of complex and diverse manifestations that vary with age. The clinical picture of this condition can be very variable and the severity of the pulmonary, immunological and neurological manifestations varies widely between patients and is related to the severity of the underlying mutations and any residual ATM kinase activity. It has been recently suggested that the name A-T should be replaced by ATM syndrome. ATM syndrome represents a neurodegenerative disorder with multisystem involvement due to the absence or reduced levels of ATM protein and kinase activity. The syndrome is characterised by the presence of movement disorders, such as cerebellar ataxia, dystonia, chorea and myoclonus, in association with systemic abnormalities such as immunodeficiency, malignancies, oculocutaneous telangiectasias and an increase in α-fetoprotein levels. The disease most commonly presents with ataxia during the third or fourth year of life. The important first step in the evaluation of young children presenting with ataxia should be α-fetoprotein testing. The diagnosis should then be confirmed by genetic testing to identify the mutations and measure the product of the ATM gene, the protein kinase ATM. This diagnostic test is likely to be available in specialised laboratories only. Patients with A-T die prematurely, the leading causes of death being respiratory diseases and cancer. A minimally estimated annual mortality rate for white patients is 19.5/1000 for ages 15–19 years and reportedly three-fold higher for African-American patients.

Historical Perspective

The term Ataxia-Telangiectasia was initially advanced by Boder and Sedgwick in 1957,in which described eight patients with classical A-T, while in 1958 Centerwall and Miller entitled it Louis-Bar syndrome which relates to Madame Louis-Bar, a Belgian neurologist who published a case report of a 9 year-old boy with cutaneous telangiectasia and progressive cerebellar ataxia. She initially classified this new disease in the group of phacomatosis PPV. In 1993, a case report was published about a 17 year-old boy with cerebellar ataxia concomitant dystonia, myoclonus, pyramidal signs, pulmonary infection, persistent lymphopenia, immunoglobulin deficiency and rising alpha-fetoprotein, termed as ataxia with immune deficiency.^[1] In 1995, the responsible gene for A-T(ATM) was identified by Savitsky et al. In 2001, Stewart found a correlation with ATM kinase activity levels in cells and the degree of neurological symptoms in A-T patients.^[2]