Mapping a gene for familial hypertrophic cardiomyopathy to chromosome 14q1

Article Abstract:

Familial hypertrophic cardiomyopathy is a disease in which the heart muscle becomes enlarged for no apparent reason. The disease often affects the left ventricle, the heart's main pumping chamber, in an asymmetric or regional manner. The actual appearance of the anatomic features of the condition is variable and the severity may also vary greatly. It is known that the condition is inherited as an autosomal dominant condition, meaning that a child receiving the gene from either parent will develop the condition. This study used DNA probes, genetic marker compounds, to identify the area of a chromosome that is responsible for this inherited abnormality. A large French Canadian family was examined by electrocardiogram (EKG), a recording of the heart's electrical activity, and by noninvasive means for visualizing both the anatomic and physiologic features of their hearts (ultrasound echocardiography). These tests were done to diagnose hypertrophic cardiomyopathy. Blood cells taken from family members were evaluated by genetic mapping techniques for cardiomyopathy. In this family, the defective gene was most likely located on chromosome 14; the odds were 2 billion to one that it was located there.

Research, Evaluation, DNA probes, Chromosome mapping, Genetic disorders, Chromosome abnormalities, Cardiomyopathy, Myocardial diseases

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Mutations in the genes for cardiac troponin T and alpha-tropomyosin in hypertrophic cardiomyopathy

Article Abstract:

People with newly-discovered mutations in the gene for cardiac troponin T may have few symptoms of hypertrophic cardiomyopathy but nevertheless have a high risk of sudden death. Hypertrophic cardiomyopathy is a type of heart disease. Researchers used DNA analysis to detect mutations in the genes for the heart muscle proteins alpha tropomyosin and cardiac troponin T in 27 families and 126 people with a family history of hypertrophic cardiomyopathy. Five families and six people had a mutation in the gene for cardiac troponin T. Only one person had a mutation in the gene for alpha tropomyosin. Eight mutations in the cardiac troponin T gene could be linked to hypertrophic cardiomyopathy and five have never been described before. Death rates were higher in young patients with a mutation in cardiac troponin T, and more died suddenly, compared to patients with the more common mutation in the heavy chain of beta cardiac myosin. However, many of the patients with the cardiac troponin T mutation had no clinical signs of heart disease.

Health aspects, Cardiomyopathy, Hypertrophic, Hypertrophic cardiomyopathy, Mutation (Biology), Mutation, Muscle proteins

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Calcium-ion-sensing cell surface receptors

Article Abstract:

Calcium ion levels in the body may be regulated by a receptor on the surface of cells in the parathyroid gland, the kidneys, and possibly other tissues. Changes in extracellular calcium levels are detected by the parathyroid and thyroid glands, which release hormones that affect calcium absorption in the intestines, kidneys, and bones. Various evidence suggests the existence of calcium receptors. Cow parathyroid cells respond similarly to extracellular calcium and to hormones that attach to receptors. Calcium ion receptors on cow parathyroid cells and rat kidney cells have been isolated and analyzed. Two genetic diseases humans, hypocalciuric hypercalcemia and neonatal severe hyperparathyroidism, involve the inability of the kidneys and parathyroid to sense calcium levels. The mutations that cause some cases of these diseases rendered the cow calcium receptor inactive. There is also evidence suggesting that the kidneys respond not only to parathyroid hormone, but to calcium directly.

Physiological aspects, Calcium in the body, Calcium (Nutrient)

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