Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004134 (ataxia)
 15,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ataxia-telangiectasia (A-T) is caused by mutations of the ATM gene, the product of which is involved in the regulation of cellular responses to radiation damage. Ataxia usually starts in early childhood but a delayed age at onset and slower rate of neurological deterioration has been found for some patients with variant A-T. Only few patients have been documented to survive into the 4th decade. We report on a patient with an attenuated form of A-T who was diagnosed as having A-T by the age of 52 years and died by the age of 60 years. He was found to be a compound heterozygote for a double missense mutation (D2625E and A2626P) and a novel splicing mutation (496 + 5G --> A) of the ATM gene. Cytogenetic studies of the patient's lymphoblastoid cells revealed modest levels of bleomycin-induced chromosomal instability. Residual ATM protein was found at a level of 10-20% of wildtype. Low residual ATM kinase activity could be demonstrated towards p53, whereas it was poorly detectable towards nibrin. Our results corroborate the view that the clinical variability of A-T is partly determined by the mutation type and indicate that A-T can extend to late adulthood disease.
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PMID:Slow progression of ataxia-telangiectasia with double missense and in frame splice mutations. 1505 41

Ataxia-telangiectasia (A-T) is a progressive neurodegenerative disorder, with onset in early childhood and a frequency of approximately 1 in 40,000 births in the United States. A-T is seen among all races and is most prominent among ethnic groups with a high frequency of consanguinity. The syndrome includes: progressive cerebellar ataxia, dysarthric speech, oculomotor apraxia, choreoathetosis and, later, oculocutaneous telangiectasia. Immunodeficiency with sinopulmonary infections, cancer susceptibility (usually lymphoid), and sensitivity to ionizing radiation are also characteristic. Laboratory findings include: (1) elevated alphafetoprotein (AFP), (2) cerebellar atrophy on magnetic resonance imaging, (3) reciprocal translocations between chromosomes 7 and 14 in lymphocytes, (4) absence or dysfunction of the ATM protein, (5) radiosensitivity, as demonstrated by colony survival assay (CSA), and (6) mutations in the ATM gene. The latter are usually truncating or splicing mutations; approximately 10% are missense mutations. Mutations are found across the entire gene. Almost all recurring mutations are found on unique haplotypes that represent founder effects and ancestral relationships between patients. In addition to radiosensitivity and sensitivity to radiomimetic chemicals, the phenotype of A-T cells includes defective damage-induced activation of the cell cycle checkpoints at G1, S and G2/M. With the aid of molecular testing, A-T can now be distinguished from other autosomal recessive cerebellar ataxias (ARCAs) such as Friedreich ataxia, Mre11 deficiency (AT-like disease), and the oculomotor apraxias 1 (aprataxin deficiency) and 2 (senataxin deficiency). Other "A-T variants" include: (1) Nijmegen breakage syndrome (NBS) or nibrin/Nbs1 deficiency, with microcephaly and mental retardation but without ataxia, apraxia, or telangiectasia, and 2) A-T(Fresno), a phenotype that combines features of both NBS and A-T, with mutations in the ATM gene. The term "A-T variant" has a diminishing usefulness.
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PMID:Ataxia-telangiectasia, an evolving phenotype. 1527 7