The errant gene that causes a hereditary form of breast cancer was an

The errant gene that causes a hereditary form of breast cancer was an especially elusive quarry. Scientists knew that the gene – dubbed BRCAI – was somewhere on Chromosome-17, but they couldn’t pinpoint an exact location or identify the culprit’s chemical makeup. Over the past four years, dozens of rival laboratories took up the search, and rumors circled the globe that one group or another had found the damaging strand of DNA. Last week, finally, researchers at the University of Utah and Myriad Genetics, a Salt Lake City company, confirmed that the often-fatal molecular flaw had been tracked down. As reports of the achievement flashed across TV screens and the front pages of newspapers, Science magazines made the unusual concession of releasing articles that described the discovery three weeks in advance of the planned publication date. “When I heard the news I cried,” says Judi Ellis of Richmond, Virginia. “It was the first time since my mother was diagnosed with breast cancer 30 years ago that anything so significant had happened.”

The discovery is indeed a major step toward understanding the origins of a disease that kills 46,000 women each year in the US alone. But it will not quickly reduce the death toll. The inheritance of a defective BRCAI gene is responsible for only about 5% of breast-cancer cases. Most apparently result from cellular changes that take place after birth. Myriad Genetics expects to devise a clinical test to detect the gene. But a foolproof test will take time to develop, because BRCAI turns out to be an unusually long, complex, gene that can be crippled by many different mutations.

Scientists don’t yet understand how the rogue gene causes breast cancer. The sequence of chemical components in this particular strand of DNA bears almost no resemblance to any other genetic message ever decoded. One section does contain a hint that BRCAI could spell out the recipe for making a particularly potent protein that may serve as a master switch in the nucleus of breast cells turning other genes on or off. Whatever BRCAI does, appears to be absolutely vital. When one copy of the gene is inactivated by a mutation and the backup copy is damaged or lost, a breast cell takes a giant step toward malignancy. So, more than 80% of all women who inherit one bad copy of BRCAI develop breast or ovarian cancer by the time they turn 70.

1. From the passage it can be safely inferred that

A. the chemical make-up of Chromosome-17 was unknown till now.
B. the location of Chromosome–17 was not known till recently.
C. the news that BRCAI had been finally located was a rumor.
D. BRCAI is a molecular flaw that often causes death.
E. normally science magazines take three weeks to publish a recent scientific discovery.


2. At the start of the second paragraph, it is mentioned that the discovery is indeed important. The author states which of the following to stress this point?

A. Normally, television programs do not flash news of science discoveries, but in this case, they were full of the reports about the latest discovery.
B. Every year about 46,000 women die due to breast cancer.
C. BRCAI code would give information about other genetic codes.
D. BRCAI is a very complex, unusually long, gene.
E. Science magazines published related articles three weeks in advance of the publishing date of the next issue.


3. BRCAI is completely different from all other known genetic codes in terms of

A. the sequence of its chemical components.
B. its location on a chromosome.
C. the action it has on the nucleus of other breast cells.
D. its complexity.
E. the effect different mutations have on it.


4. Who would stand to gain the most out of the clinic test to detect BRCAI?

A. Centres that would be allowed to administer the test.
B. Women whose families have a history of breast cancer.
C. Genetic experts who would gain more knowledge about BRCAI.
D. All the women who develop ovarian cancer by the age of 70.
E. Women who are about to die due to breast cancer.


5. From the passage it can be inferred that BRCAI is more dangerous than many other genes because

A. it serves a vital function in triggering off mutations.
B. it causes more deaths among women than any other gene.
C. all but five percent of breast cancer cases are due to BRCAI.
D. it is very different from any other known gene in its chemical components.
E. it has the capacity to turn other genes malignant even if it itself is lost or damaged.


6. What is the primary purpose of the passage?

A. To highlight a discovery and its importance, and discuss its possible future implications.
B. To highlight the hard work of the scientists in discovering BRCAI.
C. To emphasize how science is able to help in treating even those diseases about which little is known.
D. To cite reasons for celebrations over the discovery.
E. To stress that discovery of BRCAI is not as important as it has been made out to be.