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)

Ionizing radiation blocks DNA chain elongation in normal diploid fibroblasts but not in fibroblasts from patients with ataxia-telangiectasia, even though there are no differences in the damage induced between the two cell types. This difference suggests that radiation-induced lesions in DNA are not themselves blocks to chain elongation in ataxia cells and raises the possibility that in normal cells a mediator exists between DNA damage and chain termination.
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PMID:Are lesions induced by ionizing radiation direct blocks to DNA chain elongation? 661 58

Analysis of protein production in various strains of ataxia--telangiectasia (A--T) fibroblasts demonstrated the overproduction of a group of secreted proteins and variations in the protein characteristics of the extracellular matrix. The most prominent differences involved fibronectin, which was identified by immunochemical analysis. One- and two-dimensional gel electrophoresis demonstrated differences in the production, accumulation, and molecular weight of fibronectin on the cell surface and in the culture medium as compared to normal human fibroblasts. Three other secreted proteins with molecular weights of 185 000, 150 000, and 70 000 were also observed to be produced in excess amounts in some strains of A-T. The finding that extracellular matrix alterations are involved in the abnormal DNA synthesis and reduced cell survival in A-T cells in response to X radiation would be additional evidence for a close association between the extracellular and nuclear architecture.
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PMID:Altered protein synthesis in ataxia--telangiectasia fibroblasts. 683 49

A 10-year-old boy with ataxia-telangiectasia had severe progressive dystonic posturing that masked the ataxia until treatment relieved the dystonia. A younger sister had mor classical neurologic manifestations of the disease. However, both children had telangiectasia, immunologic abnormalities, and other features of ataxia-telangiectasia. The pathologic changes that have been found in the basal ganglia at autopsy and the occurrence of choreoathetosis, oculomotor disturbances, and now dystonia indicate that the function of the basal ganglia in patients with ataxia-telangiectasia is abnormal. Children who have basal ganglial abnormalities should be studied for ataxia-telangiectasia.
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PMID:Progressive dystonia masking ataxia in ataxia-telangiectasia. 738 99

Ataxia-telangiectasia is a complex syndrome that includes a very high cancer risk in children with a progressive cerebellar ataxia, the onset of which occurs in early infancy. Ocular telangiectasiae often do not appear until several years after the ataxia. The most common type of malignancy is lymphoma, usually of the B-cell type. Leukemias also occur. Failure to diagnose ataxia-telangiectasia in an infant with lymphoma or leukemia may result in radiation therapy with conventional dosages, which is contraindicated in ataxia-telangiectasia patients.
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PMID:Ataxia-telangiectasia. 771 35

We report a family of 4 siblings from a non-consanguineous marriage, presenting with an early onset recessive cerebellar ataxia and progressive distal limb wasting. Ocular or other telangiectasias were absent. There were neither frequent infections nor immunodeficiencies. The two youngest patients exhibited an incapacitating myoclonus which abated markedly after 20 years. Late onset diabetes was demonstrated in 3 patients. Hypogonadism was not a feature and there was a prolonged survival in the 4 patients. The oldest sibling died of a pancreatic adenocarcinoma. alpha-Fetoprotein was elevated with normal carcinoembryonic antigen values in three patients. Cytogenetic analysis and radioresistant DNA synthesis was compatible with the diagnosis of ataxia-telagiectasia. This family probably represents a rare variant of ataxia-telangiectasia.
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PMID:An early-onset recessive cerebellar disorder with distal amyotrophy and, in two patients, gross myoclonia: a probable ataxia telangiectasia variant. 778 63

There are several variants of ataxia-telangiectasia (A-T): classical A-T with marked radiation sensitivity; classical A-T with intermediate levels of radiation sensitivity; mild A-T with intermediate levels of radiation sensitivity; A-T without telangiectasia; A-T without oculomotor apraxia; and A-T with microcephaly. These disorders are probably caused by different allelic mutations, because affected sibs resemble the index patients, and because there is an association of certain haplotypes of 11q22-23 with specific phenotypes. The Nijmegen Breakage Syndrome, with its lack of ataxia, seems on clinical grounds to be a different disorder. Although A-T is almost always inherited as an autosomal recessive, there are some unusual features; an unexpectedly low parental consanguinity rate, an incidence in sibs that is < 0.25, and occurrence of disease in many different races and in the offspring of mixed race unions. Moreover, looking at haplotypes from 63 UK patients, there is a remarkably low incidence of homozygosity. An autosomal recessive condition that is deficient in parental consanguinity, and in homozygosity for the region around the gene, can be explained by J. H. Edwards' hypothesis that homozygosity for alleles at a neighbouring locus are lethal early in embryogenesis. Other possible mechanisms to explain the unusual genetic features are discussed.
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PMID:Clinical and genetic features of ataxia-telangiectasia. 783 49

Ataxia telangiectasia is a recessive disorder in which patients show a progressive cerebellar degeneration leading to ataxia, abnormal eye movements and deterioration of speech. Other features include ocular telangiectasia, high serum AFP levels, immunodeficiency, growth retardation and an increased predisposition to some tumours, particularly T cell leukaemia and lymphoma. We report the 1348 amino acid sequence of the N-terminal half of the A-T gene product which, together with the previously published C-terminal half, completes the sequence of the A-T protein. No homologies with other genes have been found within the N-terminal half of the A-T protein. We have also identified six mutations affecting the N-terminal half of the protein. One of these mutations was found to be associated with a haplotype that is common to four apparently unrelated families of Irish descent. All the patients so far examined for both A-T alleles were shown to be compound heterozygotes. None of these mutations affected a putative promoter region which may direct divergent transcription of both the A-T gene and a novel gene E14. The ability to recognise mutations across the entire coding sequence of the A-T gene provides a practical advantage to A-T families since a DNA based prenatal diagnosis will be possible in families where the mutations are identified irrespective of the level of radiosensitivity in these families.
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PMID:Mutations revealed by sequencing the 5' half of the gene for ataxia telangiectasia. 878 52

Ataxia-telangiectasia is a human autosomal recessive disease characterized by neurodegeneration, cancer predisposition and sensitivity to ionizing radiation. One of the earliest features of this disease is ataxia, which is thought to be attributable to a progressive cerebellar degeneration associated with a disruption of Purkinje cell cytoarchitecture and positioning. To investigate the neuropathology of ataxia-telangiectasia, we used in situ hybridization to map Atm (the gene mutated in ataxia-telangiectasia) expression during mouse development. Atm expression was highest in the embryonic mouse nervous system, where it was predominantly associated with regions undergoing mitosis. During the period of Purkinje cell neurogenesis, Atm was highly expressed in the area containing Purkinje cell precursors (the ventricular zone of the fourth ventricle). However, in the postnatal cerebellum, Atm expression in Purkinje cells was very low, while expression in proliferating granule neurons was high. The only region of the adult nervous system that exhibited elevated Atm expression were the postmitotic sensory neurons of the dorsal root ganglia. The data suggest an early developmental requirement for ATM in the cerebellum, and other regions of the central nervous system, and a potential contribution of the dorsal root ganglia/sensory input pathway to the ataxic phenotype of ataxia-telangiectasia.
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PMID:Atm expression patterns suggest a contribution from the peripheral nervous system to the phenotype of ataxia-telangiectasia. 969 12

ATM (ataxia-telangiectasia mutated) gene plays a central role in the DNA-damage response pathway. We characterized the ATM protein expression in immortalized cells from AT and AT-variant patients, and heterozygotes and correlated it with two ATM-dependent radiation responses, G1 checkpoint arrest and p53-Ser 15 phosphorylation. On Western blots, the full-length ATM protein was detected in eight of 18 AT cases, albeit at 1-32% of the normal levels, whereas a truncated ATM protein was detected in a single case, despite the prevalence among cases of truncation mutations. Of two ataxia without telangiectasia [A-(T)] cases, one expressed 20% and the other approximately 70% of the normal ATM levels. Noteworthy, among ten asymptomatic heterozygous carriers for AT, normal amounts of ATM protein were found in one and reduced by 40-50% in the remaining cases. The radiation-induced phosphorylation of p53 protein at serine 15, largely mediated by ATM kinase, was defective in AT, A(-T) and in 2/4 heterozygous carriers, while the G1 cell cycle checkpoint was disrupted in all AT and A(-T) cases, and in 3/10 AT heterozygotes. Altogether, our study shows that AT and A(-T) cases bearing truncation mutations of the ATM gene can produce modest amounts of full-length (and only rarely truncated) ATM protein. However, this limited expression of ATM protein provides no benefit regarding the ATM-dependent responses related to G1 arrest and p53-ser15 phosphorylation. Our study additionally shows that the majority of AT heterozygotes express almost halved levels of ATM protein, sufficient in most cases to normally regulate the ATM-dependent DNA damage-response pathway.
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PMID:ATM protein and p53-serine 15 phosphorylation in ataxia-telangiectasia (AT) patients and at heterozygotes. 1086 1

Ataxia with oculomotor apraxia (ataxia-telangiectasia-like syndrome [AOA]; MIM 208920) is an autosomal recessive disorder characterized by ataxia, oculomotor apraxia, and choreoathetosis. These neurological features resemble those of ataxia-telangiectasia (AT), but in AOA there are none of the extraneurological features of AT, such as immunodeficiency, neoplasia, chromosomal instability, or sensitivity to ionizing radiation. It is unclear whether these patients have a true disorder of chromosomal instability or a primary neurodegenerative syndrome, and it has not been possible to identify the defective gene in AOA, since the families have been too small for linkage analysis. We have identified a new family with AOA, and we show that the patients have no evidence of chromosomal instability or sensitivity to ionizing radiation, suggesting that AOA in this family is a true primary cerebellar ataxia. We have localized the disease gene, by linkage analysis and homozygosity mapping, to a 15.9-cM interval on chromosome 9q34. This work will ultimately allow the disease gene to be identified and its relevance to other types of autosomal recessive cerebellar ataxias to be determined.
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PMID:Autosomal recessive cerebellar ataxia with oculomotor apraxia (ataxia-telangiectasia-like syndrome) is linked to chromosome 9q34. 1102 12


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