北里大學で2014年に出題された問題です。月曜日と金曜日に、パラグラフ毎に解説して參ります。
次の英文を読み、下記の設問に答えなさい。
Scientists have long known that specific genes are associated with a number of serious diseases and birth defects. Scientists have used this knowledge to develop tests to identify defective genes, which are the result of mutation: a natural process that alters genetic material. Researchers have identified a large number of genes that are responsible for life-threatening conditions, such as cystic fibrosis*1 and Huntington’s disease*2. ( 1 ) these genes are identified, genetic tests for many such diseases become available. These tests can indicate if a person has a specific defective gene. By 2011, researchers had developed more than 2,000 genetic tests, which allow doctors to inform patients if they have inherited these genes and if they risk passing them on to their children.
This testing is a significant milestone in genetic research, because these tests provide people who have genetic defects ( 2 ) important information. However, the tests also introduce complex ethical issues. If patients find out that they have a dangerous genetic defect, they may not know what to do. Their decision will depend on several factors. First, in some cases, identification of the gene only suggests the likelihood that the patient will develop the disease associated with that gene. For example, women who have inherited the harmful BRCA gene mutation*3 have a much higher chance of developing breast cancer than other women do. ( 3 ), it is likely that women with the genetic mutation will develop cancer, but it is not certain. A second important factor in the decision is whether there is a treatment, and if so, what kind of treatment. In the case of BRCA gene mutation, a frequent treatment is major surgery before the cancer develops. Women who test positive for the mutation must decide between this treatment and the possibility of dying of cancer.
Unfortunately, for some genetic diseases, there is no treatment, which (6)gives rise to even more complex ethical issues. Would patients want to know that they are going to die young or become very sick if there is no treatment? Some may want to know so that they can prepare themselves. If there is a chance they could pass the disease to their future children, they may decide not to have children. For others, however, the news could ruin their lives. They might prefer not to know about their condition and enjoy their lives while they are healthy. So, they may decide not to get genetic tests at all.
Most researchers expect that the next step will be gene therapy that repairs or replaces the defective gene. This would mean, for example, that BRCA patients could receive a treatment that actually changes their genetic material. If that came true, most people would probably decide to take genetic tests.
At the end of the 20th century, researchers began to develop treatments for a variety of life-threatening genetic diseases. The early results seemed very (7)encouraging, and, consequently, people with genetic diseases became hopeful that they would soon see a cure. In 2000, for example, French doctors treated babies with a rare genetic disorder, commonly (8)referred to as “bubble boy disease*4,” that affected their immune systems. They injected the babies with a healthy replacement gene. Ten months later, the children’s immune systems appeared completely normal.
To these early achievements, however, considerable problems and limitations were attached. Results were ( 4 ); success occurred in only a small number of patients with rare conditions. Sometimes the therapy caused more problems than it solved. For example, in the French case, several of the children developed leukemia*5, one of whom died. In addition, enthusiastic researchers sometimes (9)underestimated the time it would take for discoveries in the laboratory to become practical therapies, a difficulty that persists today, often leading to disappointment and a lack of confidence in the field of gene therapy.
In spite of these ( 5 ), many scientists pursued their research in gene therapy. They believed this form of treatment still held great potential. However, three basic technical challenges (10)stood in the way of their progress. First, gene therapy is not like other kinds of treatments in which a patient can take a pill that sends medicine throughout the body. It must be introduced into specific genes. Second, scientists need a way to deliver the therapy directly into a cell. In many cases, they have used a virus to do this, but they have to be sure that the virus will not harm the patient. Finally, they have to be sure that the new or repaired gene will not “turn off” after it is introduced into the cell.
After years of research and trials, scientists had made considerable progress in solving these problems. In the first years of the 21st century, positive results began to emerge, arousing renewed interest in the field. In a small clinical trial in 2007, patients with Parkinson’s disease*6 received genes for production of an important protein that they lacked. All 12 patients experienced an improvement in their condition with no negative effects. In 2011, researchers successfully treated patients with hemophilia*7, a disease that impairs the body’s ability to clot blood, by injecting them with the healthy form of a defective gene. These were major achievements, but they are particularly exciting because the treatments are for major diseases that affect large numbers of people.
All of these positive results have revived the public’s interest in gene therapy. Many researchers and scientists have renewed their belief in the prospect of its enormous potential to treat killer diseases like cancer, diabetes, cystic fibrosis, etc. However, they are now more careful to caution patients and society that many effective genetic therapies may still be years, or decades, in the future. [933 words]
出典： Making Connections 3: Skills and Strategies for Academic Reading, 3rd Edition by Kenneth J. Pakenham, Jo McEntire and Jessica Williams, pp. 27-29 © Cambridge University Press 2013.
注：
*1cystic fibrosis 「嚢胞性纖維症」肺、膵臓、消化管、汗腺などの外分泌腺の機能が損なわれる遺伝性疾患
*2Huntington’s disease 「ハンチントン病」常染色体優性遺伝によって発病する神経変性疾患
*3BRCA gene mutation「がん抑制遺伝子変異」BRCA gene = breast cancer (susceptibility) gene
*4bubble boy disease「バブルボーイ症候群、重症複合免疫不全症」アデノシンデアミナーゼという酵素の欠損に起因する免疫不全疾患
*5leukemia「白血病」血球を作る細胞（幹細胞）が、骨髄中でがん化して無制限に増殖し続ける病気
*6Parkinson’s disease 「パーキンソン病」中脳黒質にあるドーパミン神経細胞が脱落することによる中枢神経系疾患
*7hemophilia 「血友病」止血に必要な凝固因子が不足するため、いったん出血すると血が止まりにくい病気
問１ 本文中の(1)～(5)の空欄に入る最も適切なものを、それぞれ①～⑤の中から一つずつ選びなさい。
(1) ① Hence ② In order that ③ Once ④ Unless ⑤ Whereas
(2) ① against ② for ③ into ④ off ⑤ with
(3) ① Besides ② Instead ③ Nevertheless ④ Otherwise ⑤ Thus
(4) ① cost-effective ② mixed ③ punctual ④ reflective ⑤ reluctant
(5) ① advances ② emissions ③ praises ④ setbacks ⑤ utilities
問２ 本文中の下線部(6)～(10)の語(句)に最も近い意味のものを、それぞれ①～⑤の中から一つずつ選びなさい。
(6) give rise to
① brings about ② cuts down ③ speeds up ④ takes the place of ⑤ turns away
(7) encouraging
① absurd ② constant ③ depressing ④ promising ⑤ unfavorable
(8) referred to as
① called ② prejudiced ③ regulated ④ unpredictable ⑤ worsened
(9) underestimated
① held high ② incorrectly judged ③ put emphasis on ④ took pride in ⑤ thought twice about
(10) stood in the way of
① turned from ② ensured ③ paralleled ④ relied on ⑤ blocked
問３ 下記の(11)～(15)の各問に対する答えとして最も適切なものを、それぞれ①～⑤の中から一つずつ選びなさい。
(11) According to the reading, what is the final target of developing gene therapies?
① Permanent repair or replacement of defective genes.
② Identification of defective genes.
③ Development of genetic tests to identify people with defective genes.
④ Development of a delivery system in which no viruses are used.
⑤ Development of a pill that sends medicine throughout the body.
(12) According to the reading, which is an example of how genetic tests can be helpful?
① By enhancing people’s immune systems.
② By protecting normal genes.
③ By causing complex ethical problems.
④ By preventing people from knowing whether or not they will have genetic diseases.
⑤ By helping people make informed decisions about having children.
(13) Which of the following (A) to (E) are described in the reading as the practical challenges that genetic researchers face in developing therapies? Choose all of the three options which apply.
(A) They have to find a good way to introduce the therapy into the cell.
(B) They have to make sure that the new or repaired genes remain active.
(C) They have to make sure that the patient’s blood is able to clot after injuries.
(D) They have to be sure that the viruses to be used for the therapy are not harmful.
(E) They have to convince more medical practitioners to take part in the therapy.
① (A), (B), and (C) ② (A), (B), and (D) ③ (A), (B), and (E) ④ (B), (C), and (D) ⑤ (B), (D), and (E)
(14) Which of the following is in accordance with the reading?
① Women who have inherited the BRCA gene mutation are less likely to develop breast cancer than those who haven’t.
② Several French children suffering from a rare genetic disease were injected with a healthy replacement gene in 2000 but none of them survived the treatment.
③ Neither side effects nor unexpected fatal accidents have happened as the results of gene therapy.
④ The time associated with developing practical gene therapies is a problem that has not yet been completely overcome.
⑤ It was proven that patients with hemophilia would not benefit from gene therapy because the disease has no relation to their genes.
(15) According to the reading, which statement best summarizes the state of gene therapy today?
① It has been so successful that any kind of gene therapy has become available anywhere on Earth.
② It is likely that only patients with rare genetic diseases will ever benefit from genetic research.
③ Recent success has allowed people to expect increased availability of genetic treatments in the years to come.
④ There have been enough failures to cause serious doubts about the overall value of gene therapy.
⑤ The age when BRCA patients were forced to decide between major surgery and the possibilities of dying of cancer has already ended.
