Identification of mutations in the COL4A5 collagen gene in Alport syndrome

Article Abstract:

Alport syndrome (AS) is a hereditary condition characterized by impaired renal (kidney) function, mild or profound deafness, eye abnormalities, and changes in some types of blood cells. The pattern of symptoms, and other evidence, suggest that AS may be related to a defect in type IV collagen, the fibrous protein that is the main component of the glomerular basement membrane (GBM, a membrane important for urine filtration in the kidney.) Researchers have attempted to locate the gene responsible for manufacturing type IV collagen, and have recently identified a gene, COL4A5, that appears to code for one of the proteins contained in Type IV collagen; this protein is located in the GBM. Since COL4A5 lies in a position on the genome near the AS locus, it seems likely that the gene is important in the development of the syndrome. To investigate this possibility, genetic material from one or two affected males from each of 18 unrelated families afflicted with AS was examined to detect the presence of mutations in the COL4A5 gene. In three of the families, specific mutations appeared. The exact nature of these genetic alterations is described. When the effects of mutations at these loci are known, the role of type IV collagen in basement membranes may be better understood. In AS, basement membranes in both the kidney and the ear are apparently defective; the patient with the most severe hearing deficit also had a large genetic deletion in COL4A5. Such results could ultimately lead to therapeutic approaches aimed at correcting the fundamental defect in AS. (Consumer Summary produced by Reliance Medical Information, Inc.)

Glomerulonephritis, Collagen diseases, Alport's syndrome

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Inheritance of proliferative breast disease in breast cancer kindred

Article Abstract:

Certain types of breast cancer are inherited, and some individuals have up to 10 times the risk of developing breast cancer because of a genetic predisposition. This study shows that patients with proliferative breast disease (PBD) may also have an increased risk of developing breast cancer. PBD is characterized by noncancerous growth of epithelial cells of the ducts of the breasts. The association between PBD and breast cancer was studied in 103 women (among 20 different families) with two first-degree relatives with breast cancer, and in 31 control women without a family history of breast cancer. Physical examinations, mammography, and needle aspirates from breast tissue were performed on all subjects. Analysis of breast tissue showed that 35 percent of the women with a family history of breast cancer, but who were clinically normal, had PBD, while only 13 percent of the women without a family history of breast cancer had PBD. This study concluded that individuals could be genetically susceptible to PBD and breast cancer, and provides evidence for the current theory that several genetic changes are necessary for the progression to cancer. (Consumer Summary produced by Reliance Medical Information, Inc.)

Risk factors, Breast cancer, Breast diseases

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Progress in progressive hearing loss

Article Abstract:

More than one-third of people over 60 and 16% of adults have a hearing loss of at least 25 decibels. Nothing is known about progressive hearing loss, except that it is attributable to both genetic and environmental aspects. New research on autosomal dominant hearing loss is presented.

Hearing loss

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