Parkinson's disease gene mutation found.After announcing last November that they were closing in on a mutant gene mutant gene n. A gene that has lost, gained, or exchanged some of the material it received from its parent, resulting in a permanent transmissible change in its function. that causes Parkinson's disease Parkinson's disease or Parkinsonism, degenerative brain disorder first described by the English surgeon James Parkinson in 1817. When there is no known cause, the disease usually appears after age 40 and is referred to as Parkinson's disease. (SN: 11/30/96, p. 348), scientists have captured their quarry. Unexpectedly, the normal form of the gene encodes a protein implicated im·pli·cate tr.v. im·pli·cat·ed, im·pli·cat·ing, im·pli·cates 1. To involve or connect intimately or incriminatingly: evidence that implicates others in the plot. 2. in Alzheimer's disease Alzheimer's disease (ăls`hī'mərz, ôls–), degenerative disease of nerve cells in the cerebral cortex that leads to atrophy of the brain and senile dementia. , another neurodegenerative disorder neurodegenerative disorder Neurology A chronic progressive neuropathy characterized by selective and generally symmetrical loss of neurons in motor, sensory, or cognitive systems Types by area Cerebral cortex–Alzheimer's disease, Pick's disease, Lewy body . While only a small percentage of the millions of people worldwide with Parkinson's disease may have the mutant gene, researchers hope its discovery will provide a clue to the origins of the remaining cases. "This is a great step forward for Parkinson's disease research that will really unlock the disorder's pathogenesis in the same way that finding [Alzheimer's] mutations unlocked the pathogenesis of that disease," predicts John Hardy of the Mayo Clinic in Jacksonville, Fla. Parkinson's disease results from the gradual death of brain cells, particularly those that produce the neurotransmitter dopamine dopamine (dōp`əmēn), one of the intermediate substances in the biosynthesis of epinephrine and norepinephrine. See catecholamine. dopamine One of the catecholamines, widely distributed in the central nervous system. . Such cells often control movement, which explains why tremors are a typical symptom of the disease. Scientists have had few clues to what causes Parkinson's disease, although the brain cells of patients contain mysterious lumps called Lewy bodies. Some investigators believe Lewy bodies trigger cell death, while others suspect they are a by-product by·prod·uct or by-prod·uct n. 1. Something produced in the making of something else. 2. A secondary result; a side effect. by-product Noun 1. of that destruction. In one Italian and three Greek families plagued by Parkinson's disease, researchers have now traced the origin of the illness to a mutation in the gene for a protein called alpha-synuclein. Mihael H. Polymeropoulos of the National Human Genome Research Institute in Bethesda, Md., and his colleagues report their finding in the June 27 Science. "The next step is to figure out what the normal function of alpha-synuclein is and whether it aggregates in the Lewy bodies," says study coauthor Lawrence I. Golbe of the Robert Wood Johnson Medical School Robert Wood Johnson Medical School (often abbreviated RWJMS) is one of eight schools that comprise the University of Medicine and Dentistry of New Jersey (UMDNJ). RWJMS operates three campuses in New Jersey, in Piscataway, New Brunswick and Camden. in Piscataway, N.J. Alpha-synuclein may play a role in synapses, connections that allow brain cells to communicate with one another. The researchers suggest that mutant forms of alpha-synuclein may aggregate abnormally and thus kill cells or cause other proteins to do so. If so, Parkinson's disease could resemble Alzheimer's, which many investigators now attribute to the accumulation in the brain of a protein fragment called beta-amyloid. "There are all these nebulous connections [between the two diseases]," says Hardy. For example, relatives of people with Alzheimer's have a higher than average risk of Parkinson's and vice versa VICE VERSA. On the contrary; on opposite sides. . Moreover, the brains of Alzheimer's patients often exhibit Lewy bodies. Finally, researchers discovered several years ago that alpha-synuclein is a major component of the amyloid plaques that develop in Alzheimer's disease. Investigators note that current therapies for Parkinson's disease address only symptoms. The finding of a mutant gene now "sets the stage to develop research ideas aimed at the cause and not just the symptoms," says Polymeropoulos. |
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