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Query: UMLS:C0004135 (ATM)
 13,001 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Trisomy 21 (Down's syndrome, DS) is the most frequent chromosomal aberration. Triplication of a small region of chromosome 21, the fragment 21q22 is sufficient to cause the DS phenotype including immunodeficiency, premature aging, neurodegenerations, mental retardation and an increased risk of leukemia. Chromosomal aberrations caused by X-ray irradiation were observed in DS lymphocytes and DS fibroblasts, but the correlation to cell death or repair deficiency was not clear. We approached this problem and report here on a profound X-ray repair deficiency of DS cells. With a colorimetric viability assay we observed an UV sensitivity of DS fibroblasts at doses beyond 14 Jm-2 but no significant X-ray sensitivity. By the nucleoid sedimentation technique, a deficient restoration of nucleoids in DS cells after X-ray irradiation was demonstrated. The same features apply for cells, which contain an overexpressed Cu/Zn-superoxide dismutase (SOD-1) gene. Radiation sensitivity of DS cells and SOD-1 overexpressing cells resemble those of ataxia telangiectasia (AT) fibroblasts. Additionally, DS and AT cells exert lack of inhibition of DNA synthesis after X-ray irradiation.
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PMID:Radiation sensitivity of Down's syndrome fibroblasts might be due to overexpressed Cu/Zn-superoxide dismutase (EC 1.15.1.1). 252 18

It is most unlikely that there is a single 'pre-eclampsia (PE) gene'. We are probably looking for a cluster of polymorphisms which, possibly in conjunction with environmental factors, predispose to the development of the condition. Accurate phenotyping is vital for any genetic studies of PE, and since the disease is only clinically-detectable in the second half of pregnancy, is particularly difficult. It is increasingly likely that there is a fetal genetic contribution which can only be examined after birth. Candidate genes examined on the basis of displayed or hypothetical pathophysiological effects, but for which no evidence of association or linkage has been found have included HLA-DRbeta, HLA-G, and tumour necrosis factor alpha (chromosome 6), angiotensin-converting enzyme (chromosome 17) and CuZn superoxide dismutase (chromosome 21). Chromosomal exclusion mapping and a pedigree study suggest a role for genes on chromosomes 1, 3, 4, 9 or 18. Two genes concerned with clotting, those for factor 5 and methylenetetrahydrofolate reductase, lie on chromosome 1. Both have polymorphisms present in significantly higher frequency in women with PE, as well as showing functional abnormality. They probably predispose to the development of the condition, without being necessary for it. The angiotensinogen (Aogen) gene also lies on chromosome 1. The renin-angiotensin system may be activated during the early stages of PE and subsequently suppressed. In some populations, a relatively common polymorphism is present in raised frequency in women with PE, but it is also raised in non-pregnant hypertensive subjects. However, it is in partial linkage disequilibrium with another polymorphism which shows significantly distorted transmission from mother to fetus in PE pregnancies. Furthermore, its expression is significantly raised in the decidual spiral arteries; abnormal placentation is a feature of PE. We have also shown that a relatively common polymorphism in the angiotensin AT1 receptor gene (chromosome 3) is associated with raised density of the receptor. Thus far, studies of candidate genes have been on a small scale and have very much reflected the pathophysiological research interests of the investigators. The multifaceted nature of PE and the difficulties of accurate phenotyping require the accumulation of a large, very carefully phenotyped, database. It is hoped that funding will become available this year in the UK to allow the collection of such a database. The introduction of chip technology should allow genome scanning of the resource.
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PMID:What is the place of genetics in the pathogenesis of pre-eclampsia? 1056 60

Among the causes of premature ovarian failure (POF) two groups of factors are reported: factors which lead to decrease of follicular number and factors which stimulate follicular atresia. In the first group genetic factors are the most important whereas in the second: enzymatic autoimmunological, iatrogenic, toxins and infections are reported. In 1986 familiar POF on the background of long arm of chromosome X deletion was reported. Other chromosomes which are important for normal ovarian function are: chromosome 21 (AIRE gene), chromosome 11 (gene of beta FSH, ATM gene), chromosome 3 (gene responsible for BEPS syndrome) and chromosome 2 (genes of FSH and LH receptors). In this review the role of these genes and results of several epidemiological studies are reported.
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PMID:[Genetic aspects of premature ovarian failure]. 1635 Jul 32

Recently it has been suggested that the human brain contains aneuploid cells; however the nature and magnitude of neural aneuploidy in health and disease remain obscure. Here, we have monitored aneuploidy in the cerebral cortex of the normal, Alzheimer's disease (AD) and ataxia telangiectasia (AT) brain by molecular cytogenetic approaches scoring more than 480,000 neural cells. Using arbitrarily selected set of DNA probes for chromosomes 1, 7, 11, 13, 14, 17, 18, 21, X and Y we have determined the mean rate of stochastic aneuploidy per chromosome as 0.5% in the normal human brain (95%CI 0.2-0.7%; SD 0.2%). The overall proportion of aneuploid cells in the normal brain has been estimated at approximately 10%. In the AT brain, we observed a 2-to-5 fold increase of stochastic aneuploidy randomly affecting different chromosomes (mean 2.1%; 95%CI - 1.5-2.6%; SD 0.8%). The overall proportion of aneuploid cells in the brain of AT individuals was estimated at approximately 20-50%. Compared with sex- and age-matched controls, the level of stochastic aneuploidy in the AD brain was not significantly increased. However, a dramatic 10-fold increase of chromosome 21-specific aneuploidy (both hypoploidy and hyperploidy) was detected in the AD cerebral cortex (6-15% versus 0.8-1.8% in control). We conclude that somatic mosaic aneuploidy differentially contributes to intercellular genomic variation in the normal, AD and AT brain. Neural aneuploidy leading to altered cellular physiology may significantly contribute to the pathogenesis of neurodegenerative diseases. These data indicate neural aneuploidy to be a newly identified feature of neurodegenerative diseases, similar to other devastative disorders hallmarked by aneuploidy such as chromosome syndromes and cancer.
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PMID:Aneuploidy in the normal, Alzheimer's disease and ataxia-telangiectasia brain: differential expression and pathological meaning. 1934 45

It is assumed that the genetic mechanism of pathogenesis of such widely spread neural and mental diseases as schizophrenia (SZ), autism, ataxia-telangiectasia (AT), and Alzheimer's disease (AD) is associated with structural and functional genomi? instaility in brain cells. Aneuploidy is one of the most important biological markers of genomic instability. The currently available methods of molecular cytogenetics (I-mFISH, QFISH, and ICS-MCB) facilitate the solution of numerous fundamental biological problems, including analysis ofgenomic variations in brain cells. Using these methods, we have studied for the first time aneuploidy in human embryo and adult brain cells (normal and with AT, AD, and SZ) as well as in blood cells of children with autism. The level of aneuploidy was increased two- to threefold in the embryo brain with a subsequent reduction of the number of abnormal cells in the adult brain. In the case of SZ, mosaic aneuploidy for chromosomes 1, 18, and X was found. The study of blood cells from children with autism showed chromosomal mosaicism for chromosomes X, 9, and 15. In the case of AT, we observed a global expression of aneuploidy in up to 20-50% of cortex and cerebellum neurons. In addition, a local instability of chromosome 14 was revealed in the degenerating cerebellum in the form of breaks in the 14q12 region. In the case of AD, a tenfold increase was observed in the level ofaneuploidy for chromosome 21 in brain sections subjected to neurodegeneration. These data indicate that mosaic genomic instability in nerve cells is one of the mechanism of neurodegenerative and mental diseases.
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PMID:[Instability of chromosomes in human nerve cells (normal and with neuromental diseases)]. 2125 54