Word: dna
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Dates: during 1990-1999
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...discovery of the CF gene has revolutionized the diagnosis of CF. Some public health experts believe that since doctors can identify the defective DNA (which occurs in 1 out of 25 Americans) they should screen all prospective parents. Men and women who find that they are both carriers might then choose to adopt or conceive with donor sperm or eggs. Last November the National Institutes of Health financed a handful of pilot projects to help it decide whether a massive screening program would be worth the considerable cost...
Many doctors are not so sure. "Just because we technically know how to test for the DNA, doesn't mean we are ready to do this on a large scale," asserts Collins. The test is imperfect, he notes; it picks up just 85% of carriers. A positive result, moreover, means only that the couple has a 1 in 4 chance of having a baby with the disease. Without proper counseling, Collins says, people might feel needlessly alarmed...
Assistant Professor of Medicine Dr. Mehmet Ozturk and his associates at the Massachusetts General Hospital (MGH) have isolated the poison, known as aflatoxin B[1], which causes a DNA sequence mutation common to many cancers...
Strong evidence for aflatoxin's role in liver cancer appeared when researchers found that in four out of five DNA sequences examined, one amino acid, guanine, was converted to anther, thymine. The poison had previously been demonstrated to cause guanine to mutate to thymine in the liver. Hepatitis B, which is another cause of liver cancer, does not cause this same mutation...
...myotonic dystrophy, the most common form of muscular dystrophy, the change can be far from negligible: a fragment of DNA on chromosome 19 appears to repeat itself more frequently with every generation. Just what triggers the repetition is a mystery. Researchers surmise that a hitch occurs while DNA is being copied in the cell, much as the same bar of music repeats on a scratched record. The DNA repeat gets worse with each generation, just as with each playing of a flawed record, the music stutters for a longer period. "Presumably the replication error occurs in the sperm...