Word: dna
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Dates: during 1990-1999
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Composed of long chains of DNA containing perhaps 100,000 genes, the human genome is far too vast to analyze all at once. So scientists use special enzymes to chop the chromosomes into small manageable pieces and pick out small identifiable stretches -- called markers -- on each segment. When researchers are searching for a disease gene, they look for a marker that is common to all people who suffer from that ailment. If one is found, then the defective gene is probably located somewhere near that marker. The problem is that although the gene hunters know where the marker is located...
That's why Cohen's new map will come in handy. To produce it, his group sliced many sets of chromosomes into thousands of segments and put each piece into a yeast cell. The cells then made thousands of copies of every piece of the human DNA. By studying different possible arrangements, Cohen's computerized machines were able to figure out the positions of a whole list of common markers as well as the proper order of the pieces...
Cohen's laboratory now has in storage multiple copies, or clones, of about 33,000 chromosome segments. So if gene hunters want to search the area around a particular marker, they can request copies of the relevant DNA segments. Says Cohen: "You can call and say, 'I need this and this clone,' and you'll get it in two days...
...Yeshorim runs five test centers in the New York area. Each participant receives a six-digit identification number and gives a blood sample; test workers analyze his or her DNA to determine whether it contains certain disease-carrying genes. Before two members of the community begin dating or decide to get married, they can call a hot line which tells them whether or not they risk passing any of the diseases to their children...
Most people are somewhat comfortable with the idea of testing for Tay-Sachs, a fatal, degenerative neurological condition that strikes young children. However, many question the utility of DNA screening for other conditions like Gaucher's disease. The symptoms of this painful degenerative disease almost never appear before a person's mid-40s, and Gaucher's is treatable. Should the distant prospects of non-fatal disease prevent a marriage between two people who love each other? Inevitably, the more diseases added to the list, the more marriages prevented...