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  3. The Gene Variation Causes an Autism Common genetic variations that can contribute to autism have been reliably identified fo

The Gene Variation Causes an Autism Common genetic variations that can contribute to autism have been reliably identified fo

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问题                  The Gene Variation Causes an Autism
    Common genetic variations that can contribute to autism have been reliably identified for the first time in research that promises to improve the diagnosis and understanding of the disorder. The DNA changes, which affect genes involved in early brain development, are together involved in up to 15 percent of autism cases, the most extensive study of its kind yet conducted has found. The findings significantly deepen scientific understanding of the genetic origins of autism, offering insights into the condition’s underlying biology that could eventually lead to new treatment.
    While it has long been established that autism has a strong inherited component, previous research has failed to reveal any common DNA variants that were involved. The new study has found a robust link between autism and six such variants. These do not invariably cause the condition, but they are about 20 percent more common in children with autism than they are in those who are unaffected. The results are especially significant because the variants lie between two genes, called CDH9 and CDH10, which are known to play an important role in forming nerve connections in the brain.
    Hakon Hakonarson, of the Children’s Hospital of Philadelphia in the United States, who led the research, said: " Because other autism researchers have made intriguing suggestions that autism arises from abnormal connections among brain cells during early development, it is very compelling to find evidence that mutations in genes involved in brain interconnections increase a child’s risk of autism". This comprehensive research opens the door to more focused investigations into the causes of autism disorders. It moves the field of autism research significantly ahead, similar to the way oncology research progressed a few decades ago with the discovery of specific genes that give rise to cancers.
    In the study, the research team compared the DNA of 3,100 individuals from 780 American families each with at least two autistic children. The scan was then repeated in a group of 1, 200 people with autism and nearly 6, 500 unaffected controls. This revealed six genetic variants that were significantly more common in the autistic group. All were on chromosome five, and appear to affect the CDH9 and CDH10 genes. The CDH9 and CDH10 genes affect the way that nerve cells in the brain communicate with one another, which is thought to be a problem in autistic spectrum disorders (ASD). Autism involves a characteristic triad of symptoms: impairments in social and communication skills, as well as repetitive behavior and/or narrowly restricted interests. It is estimated that as many as one in 150 people have a disorder on the autistic spectrum.
People with autism may suffer from all the following symptoms EXCEPT______.
选项 A、poor social skills
B、memory loss
C、limited interests
D、repeating similar behavior
答案B
解析 事实细节题。根据文章最后一段，可以看出患有自闭症的病人容易表现出的症状包括[A]选项“较差的社交能力”；[C]选项“兴趣狭窄”；[D]选项“刻板行为”，只有[B]选项“丧失记忆力”是原文没有提到的，因此是本题正确答案。
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