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  • 案例研究 -- -- 我们的相似性和差异

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    Case Study: Your Genes May Help You Save a Life
    ::案例研究:你的基因可以帮助你拯救生命

    Like the little girl shown above, seven-year-old Tyler is battling leukemia, a type of cancer that affects blood cells. Leukemia usually starts in the bone marrow — where blood cells are produced — and it causes the production of abnormal blood cells, most commonly white blood cells. D epending on the type of leukemia, i t can also affect other types of blood cells. The abnormal blood cells replace the patient’s normal blood cells over time, which can lead to symptoms of fatigue, frequent infections, and easy bruising or bleeding. Leukemia can be fatal, but fortunately, there are some treatment options available that can prolong life — and may even cure the disease.
    ::与上面提到的小女孩一样,七岁的泰勒正在对抗白血病,这种癌症会影响血细胞。 白血病通常始于骨髓 — — 产生血细胞的地方 — — 并导致产生异常的血细胞,最常见的是白色血细胞。 根据白血病的类型,它也可以影响其他类型的血细胞。 异常的血细胞会随着时间的推移取代病人正常的血细胞,这可能导致疲劳、频繁感染、容易瘀伤或流血等症状。 白血病可能是致命的,但幸运的是,有些治疗方法可以延长生命,甚至可以治愈这一疾病。

    Tyler has undergone chemotherapy to kill the cancerous cells, but his doctors have told his parents that it is not enough. Tyler needs a bone marrow transplant in order to replace his abnormal bone marrow with healthy bone marrow. His family members are eager to donate bone marrow to him, but first they must be tested to see if they are a compatible match.
    ::泰勒接受了化疗以杀死癌症细胞,但他的医生告诉他的父母说这还不够。 泰勒需要骨髓移植,以健康骨髓取代不正常的骨髓。 他的家人渴望向他捐献骨髓,但首先必须测试他们是否匹配。

    For  blood transfusions, it is relatively easy to find a compatible blood donor, but bone marrow transplants require much more specific matching between donor and recipient. They must share several of the same type of proteins — called human leukocyte antigens (HLAs) — on the surface of their cells. One type of HLA protein is illustrated . Different people have different types of HLA proteins (or markers) depending on their specific genes. Typically, eight to ten HLA markers are tested and compared in the potential bone marrow donor and recipient. At least six or seven of these HLA markers must  be identical between them in order for a match to be made.  
    ::对于输血而言,相对容易找到兼容的献血者,但骨髓移植需要捐赠者和接受者之间更具体的匹配。它们必须在其细胞表面分享几种同类蛋白质 — — 叫做人类白血球抗原(HLAs ) 。 一种HLA蛋白可以说明其中一种。 不同的人有不同种类的HLA蛋白(或标记 ) , 取决于他们的具体基因。 通常会测试8到10个HLA标记,并将潜在骨髓捐献者和接受者进行比较。 这些HLA标记中至少有6到7个是相同的, 以便匹配。

    lesson content

    An illustration of a human leukocyte antigen protein, HLA-DQ, attached to the surface of a cell, showing its α (pink) and β (blue) chains
    ::人体白氧抗原蛋白,HLA-DQ,附于细胞表面,显示其α(粉)和β(蓝色)链

    If the match is not good, the patient’s body could reject the bone marrow transplant. Conversely, the transplanted bone marrow could produce immune cells that attack the patient’s body. A good match between donor and recipient is critical for bone marrow donation to be safe and effective.
    ::如果配对不妙,病人的身体可以拒绝骨髓移植。 相反,移植骨髓可以产生攻击病人身体的免疫细胞。 捐赠者和接受者之间的良好匹配对于骨髓捐赠的安全有效至关重要。

    A full sibling frequently provides the best match for bone marrow donation because they share many of the same genes from their parents. Tyler’s sister is tested, but unfortunately, she is not a match for him. This is not all that surprising since there is only about a 25 percent chance that a sibling will be an identical HLA match. His parents and other family members are also tested, but none of them are a match, either. Tyler must join the 70 percent of patients that need to look outside of their families for a bone marrow donor.
    ::完全的兄弟姐妹经常为骨髓捐赠提供最佳匹配,因为他们与父母拥有许多相同的基因。 Tyler的妹妹接受了测试,但不幸的是,她并不配他。 这并不奇怪,因为兄弟姐妹只有大约25%的几率是相同的HLA匹配。 他的父母和其他家庭成员也接受了测试,但都没有匹配。 Tyler必须和70%的病人一起寻找家人以外的骨髓捐献者。

    How do you find a bone marrow match outside of your family? Fortunately, people from all over the world have signed up to be potential bone marrow donors, usually by providing a simple swab of the inside of their cheek. DNA from the cells collected on the swab is then tested for HLA type. The potential donor’s HLA information is put into a donor registry, and doctors can then search national and international registries for compatible matches for their patients.
    ::幸运的是,来自世界各地的人已经报名成为潜在的骨髓捐献者,通常通过提供他们脸颊内部的简单的擦拭。 从擦拭上采集的细胞DNA随后会用HLA类型测试。 潜在捐献者HLA信息被输入捐赠者登记册,然后医生可以搜索国家和国际登记簿,为病人寻找匹配匹配的匹配对象。

    Patients are much more likely to be a match with a bone marrow donor of their same race or ethnic background. People with more similar ancestry are more likely to share similar HLA genes. In Tyler’s case, his mother is African American, and his father is Japanese and Caucasian. His relatively rare combination of ethnic backgrounds may make it harder for him to find a match in the donor registries, as is the case for many multiethnic patients.
    ::病人更有可能与同一种族或族裔背景的骨髓捐献者相匹配。 具有类似血统的人更有可能分享类似的HLA基因。 在泰勒的案例中,他的母亲是非裔美国人,他的父亲是日本人和高加索人。 他相对罕见的种族背景组合可能使他更难在捐赠者登记册中找到匹配,许多多种族患者的情况就是这样。

    Read the rest of this chapter to learn more about the genetic and phenotypic variations that exist in humans, and how some of these differences came about, due to differing natural selection pressures in different areas of the world. A t the end of the chapter, learn more about Tyler’s quest for a bone marrow donor, the need for bone marrow donors from diverse ethnic backgrounds, and how you may be able to save someone’s life based on your genetic makeup!
    ::阅读本章的其余部分是为了更多地了解人类中存在的遗传和口腔差异,以及由于世界不同地区不同的自然选择压力,这些差异是如何产生的。 在本章的结尾,更多地了解泰勒寻找骨髓捐献者、不同种族背景的骨髓捐献者的需求,以及你如何根据你的基因构成挽救某人的生命!

    Chapter Overview: Human Variation
    ::章次概览:人类变化

    In this chapter, you will learn about:
    ::在本章中,你们将了解:

    • The extent, types, and patterns of human genetic variation — both within and between populations
      ::人类基因变异的程度、类型和模式——包括人口内部和人口之间的基因变异
    • How knowledge about human genetic variation can give insight into human origins and history, and how it may lead to treatments for diseases
      ::人类基因变异知识如何能使人们深入了解人类起源和历史,以及人类基因变异如何可能导致疾病治疗
    • The ways human variation has been classified, and how some classification methods contribute to racism
      ::人类差异被分类的方式,以及某些分类方法如何助长种族主义
    • How gene flow and natural selection can result in a gradual change in the frequency of a trait over a geographic area
      ::基因流动和自然选择如何导致某一地理区域特性的频率逐渐改变?
    • The ways in which humans can adapt to environmental stresses — genetically, physiologically, and culturally
      ::人类在基因、生理和文化方面适应环境压力的方式
    • How differences in human skin color are generated, and how they likely came about evolutionarily
      ::人类肤色差异是如何产生的,它们是如何演变成进化的
    • Differences in human blood types (including the ABO and Rhesus groups), how they may have evolved, and their relationships to diseases
      ::人类血型差异(包括ABO和Rhesus群体)、它们如何演变及其与疾病的关系
    • How malaria has caused humans to develop a variety of blood cell adaptations over the course of our evolution, including the trait that causes sickle cell anemia
      ::疟疾如何导致人类在进化过程中发展出各种血细胞适应,包括导致镰状细胞贫血的特性。
    • Adaptations humans have evolved to deal with the stress of living at high altitudes and in extreme climates, and the ways people can temporarily acclimate to these environmental conditions
      ::人类的适应已经演变,以应对在高高度和极端气候中生活的压力,以及人们能够临时适应这些环境条件的方式
    • Human adaptations to our food supply, including lactose tolerance, and weight and blood sugar regulation
      ::人类对粮食供应的适应,包括乳糖耐受性、重量和血糖管制

    As you read the chapter, think about the following questions:
    ::当你读到该章时,请考虑以下问题:

    1. How similar are any two people genetically? Based on your answer, why do you think it is not easy to find an HLA match for bone marrow donation between people?
    ::1. 两个人的遗传基因有多相似?根据你的回答,你为什么认为很难找到一种HLA匹配的人与人之间骨髓捐赠?

    2. What is the concept of race? What are its limitations? How does race or ethnicity relate to genetic variation?
    ::2. 种族概念是什么?其局限性是什么?种族或族裔与基因变异有何关系?

    3. What is an antigen, such as the human leukocyte antigen? On a cellular and molecular level, what happens when there is not a good match between a tissue donor and recipient?
    ::3. 什么是抗原,例如人类白血球抗原?在细胞和分子一级,如果组织捐献者和接受者之间没有良好的匹配,会发生什么情况?