题目内容
A woman suffering from cancer during pregnancy can pass the disease on to her unborn child, scientists have shown in a study that solves a puzzle that has confused doctors for a century.
The rare occurrence of a mother and child appearing to share the same cancer---of which there have been about 30 known cases---is a result of genetic mutation (基因突变) that allows the cancer to pass to the baby unnoticed.
There was previously no genetic evidence to explain why a child’s immune system would not recognize and destroy any invasive cancer cells that were of maternal---and therefore, foreign origin.
The new study, led by Mel Greaves, of the Institute of Cancer Research (ICR), and published in Proceedings of the National Academy of Sciences, used advanced genetic fingerprinting to prove that infant’s leukaemic cells (白血病细胞) were unquestionably of maternal origin.
The case, involving a Japanese mother aged 28 and her daughter, showed that both patients’ leulaemic cells carried the identical transformed cancer gene BCR-ABL even though the infant had not inherited (遗传的) this gene.
This meant that the child, who had cancer diagnosed at 11 months, old, could not have developed this type of leukaemia in isolation.
To investigate how the cells could have crossed the placental barrier (胎盘膜) and survived in the offspring (后代), the scientists looked for evidence of some form of immunological (免疫学的) acceptance of tolerance of the foreign cells by the foetus (胎儿).
Professor Greaves, who worked with colleagues in Japan with funding from Leukaemia Reasearch, said that it had bee assumed that cancer spread was impossible because of the placenta’s role in preserving materno-foetal (母体-胎儿) health.
61. What is the main idea of the passage?
A. An Unborn child can be infected by the mother with cancer.
B. Scientists have solved a confusing puzzle for a century.
C. A genetic mutation leads to the cancer of the unborn child.
D. Women can’t be cured during pregnancy.
62. Which of the following statements is true according to the passage?
A. There are many cases of a genetic mutation causing cancer.
B. No genetic evidence is known why the unborn child was infected.
C. Mel Greaves’s study indicates the infant’s leukaemic cells were of maternal origin.
D. Based on Mel Greaves’s study, mothers may know cancer’s transportation.
63. What was used to prove the infant’s leukeaemic cells were from the mother?
A. genetic mutation B. placental barrier
C. immune system D. genetic fingerprinting
64. What does the underlined phrase “in isolation” mean in the 6 paragraph?
A. in a hurry B. in no way C. on purpose D. on its own
65. What can we infer from the passage?
A. The placental barrier doesn’t prevent any disease.
B. Earlier theories supposed cancer couldn’t go across placenta.
C. Scientists have got evidence for some diseases.
D. Professor Greaves gets money from the government.
ACDDB
