Article Abstract:
The fragile-X syndrome is an inherited form of mental retardation. With an incidence of 1 in 1,500 males, it occurs more frequently than any other form of inherited mental retardation. The location of the gene(s) involved in the disease is next to a fragile site (where the chromosome is easily broken by experimental procedures) on the X chromosome, known as q27.3. Fragile-X syndrome has an unusual pattern of inheritance for a trait linked to the X-chromosome. It can be passed by normal men to their daughters who become asymptomatic carriers of the disease and whose children, of either sex, can exhibit the genetic defect. Theories have been proposed to account for the abnormal inheritance of the mutation, including genetic rearrangements and reactivation of an inactive X chromosome. Using a process known as pulse-field gel electrophoresis, which allows analysis of large pieces of DNA, abnormalities have been seen in the gene sequence near the fragile-X locus in patients with fragile-X syndrome, and not in normal controls, nor in males who were carriers but did not show symptoms of the disease. These abnormalities showed an increase in methylation of that portion of the chromosome that was not due to rearrangement of a large portion of the chromosome, indicating inactivity in that part of the chromosome. The presence of these genetic alterations can perhaps be used in the genetic analysis to diagnose fragile-X syndrome. (Consumer Summary produced by Reliance Medical Information, Inc.)
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Article Abstract:
A gene that may be involved in X-linked adrenoleukodystrophy (ALD) has been identified using positional cloning techniques. ALD is a degenerative neurological disease having diverse phenotypical manifestations which may involve numerous factors such as immune response and helper genes. ALD involves impaired beta-oxidation of very-long-chain fatty acids (VLCFA). The newly discovered gene is not directly involved in the oxidation of VLCFA, but it may be involved in the transport of VLCFA-CoA synthetase into the peroxisomal membrane or functionally associated with it in the membrane.
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Article Abstract:
Analysis of a polyglutamine expansion in particular proteins and its link to Huntington's disease and four other brain disorders is undertaken. In particular, the existence of a monoclonal antibody that is capable of selectively identifying polyglutamine expansion is discussed. An inverse correlation was found for two variables, namely, the length of the polyglutamine expansion and the start of clinical manifestations of the disorder.
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