Hunting+for+Answers

Hunting+for+Answers - T he cups fell to the floor with a...

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Unformatted text preview: T he cups fell to the floor with a crash. Was this the alarm signal? Or was it forgetting his sisters phone number the other day, even though he calls her often? Was the telling event last weekend, when he burst into a string of curse words and tailgated the driver who had just cut him off? Incidents that to other people may seem like simple clumsiness, forgetfulness or an overreac- tion brought on by stress could mean disaster for Martin, a 48-year-old shipping agent. For years, he had been observing himself and his siblings with a sharp eye. Any little slip could constitute a somber omen. But after this latest string of mis- haps, he could not bear the uncertainty any lon- ger. He went in for the blood test. Three days later what Martin had feared since childhood was conrmed as the terrible truth: he was suf- fering from the genetic mutation that had killed his mother, his uncle and his grandfather. Huntingtons disease was recognized as an inherited disorder more than 100 years ago, yet the mutation that causes it was not discovered until 1993. A DNA test on a blood sample was quickly devised to reveal whether a person car- ried the abnormal form of the gene, which leads to progressive destruction of the brain, crippling muscles and mental function. Since then, every man or woman who has had a parent or other relative with the disease has faced a vexing choice: Should he or she take the test? A positive verdict is a damnationthe disease leads to cer- tain death, given that there is no cure. Not know- ing can be easier; most people do not begin to exhibit symptoms until they are middle-aged, and the progression can be very gradual. Yet nag- ging suspicion can creep into every corner of life, as it did for Martin. Of course, a cure, or even treatment that could slow the disease, would ease the tension greatly and extend life for the 30,000 Americans who have been diagnosed with Huntingtons. Re- searchers are pinning down just how the genetic mutation ruins cellular mechanisms inside neu- rons, knowledge that might help point the way to therapies that have thus far proved elusive. A SINGLE MUTATION CASTS THE DEATH SENTENCE OF HUNTINGTONS DISEASE. RESEARCHERS ARE PINNING DOWN HOW THAT MUTATION RUINS NEURONSKNOWLEDGE THAT MAY SUGGEST THERAPIES BY JUERGEN ANDRICH AND JOERG T. EPPLEN 70 SCIENTIFIC AMERICAN MIND April/May 2006 JUAN SILVA Getty Images HUNTING for Answers COPYRIGHT 2006 SCIENTIFIC AMERICAN, INC. COPYRIGHT 2006 SCIENTIFIC AMERICAN, INC. 72 SCIENTIFIC AMERICAN MIND April/May 2006 Lethal Knowledge The Huntingtons test is so certain because the disease is caused by a single genethe huntingtin gene on chromosome 4 (the name of the gene is spelled differently than that of the illness). Typi- cally this gene contains several occurrences of a set of DNA building blocks: cytosine, adenine and guanine, abbreviated as CAG. This set drives the production of the huntingtin protein. The more often the CAG sequence comes up in the...
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This note was uploaded on 02/03/2011 for the course BIO 80H taught by Professor Rothwel during the Spring '09 term at UCSC.

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Hunting+for+Answers - T he cups fell to the floor with a...

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