基因突變產生的十大特異功能(下)

nity To A Brain Disease

5.對腦疾病擁有免疫力

In case we needed another reason to avoid cannibalism, eating our own kind is not a particularly healthy choice. The Fore people of Papua New Guinea showed us as much in the mid–20th century when their tribe suffered through an epidemic of Kuru—a degenerative and fatal brain disease spread by eating other humans.

如果我們要給避免同類相食增加一個理由的話，從健康的角度來看，這不是一個好的選擇。巴布亞新幾內亞" Fore"族人在20世紀中期流行的庫魯病很好地說明了這一點，他們因同類相食，產生了退化性和致命性的腦疾病。

Kuru is a prion disease related to Creutzfeldt-Jakob Disease (CJD) in humans and bovine spongiform encephalopathy (mad cow disease). Like all prion diseases, kuru decimates the brain, filling it with sponge-like holes. The infected suffers through a decline in memory and intellect, personality changes, and seizures. Sometimes, people can live with a prion disease for years, but in the case of kuru, the afflicted usually die within a year of showing symptoms. It's important to note that, although very rare, a person can inherit a prion disease. However, the illness is most commonly spread by eating an infected person or ially, anthropologists and medical doctors didn't know why kuru was spreading across the Fore tribe. Finally, in the late 1950s, it was discovered that the infection was being transmitted at mortuary feasts, where tribe members would consume their deceased relatives out of respect. Mostly women and young children participated in the cannibalistic ritual. Consequently, they were the ones predominantly affected. Before the funerary practice was banned, some Fore villages had virtually no young women not all who were exposed to kuru died from it. Survivors had a novel variation in a gene called G127V that made them immune to the brain disease. Now, the gene is widespread among the Fore and surrounding people, which is surprising because kuru only popped up in the area around 1900. This incident is one of the strongest and most recent examples of natural selection in humans.

庫魯病是一種與庫茲菲德-雅各氏症和瘋牛病有關的朊病毒疾病。和所有朊病毒疾病一樣，庫魯病殺死大量腦細胞，使其產生空洞、海綿化。患者會記憶衰退，智力下降，性格改變，產生癲癇等。通常，患有朊病毒疾病的人可以繼續生活數年，但是患有庫魯病，則一般在產生症狀之後一年內便會死亡。需要注意的是（儘管非常罕見），朊病毒能夠遺傳。不過，絕大多數患者是因爲食用了產生感染的人或動物。最初，人類學家和醫生們都不知道爲什麼庫魯病會在Fore族人中大肆傳播。直到20世紀50年代末才發現這類疾病是在太平間盛宴時傳染的。因爲出於對死去親人的尊敬，Fore族人會將屍體吃掉。婦女、孩子都參加此種儀式，高峯時該病在女性和兒童中的發病率是在男性中的8至9倍。因爲該族人吞食已逝親屬的肉以完成後者的"生命循環"時，由男性先選擇所食部分，然後再由女性和兒童打掃剩下的包括腦部在內的人肉，而腦部正是致病朊毒體含量較高的部分。在這種食人習俗被禁止之前， Fore族人的一些村莊幾乎連一個年輕婦人都沒有。並不是所有患此病的人都會死亡，這些存活下來的倖存者們的G127V基因有了新變化，這使得他們對大腦疾病產生了免疫能力。現在，這種基因遍佈Fore族和周圍的人。這是令人十分驚奇的現象，因爲庫魯病是在1900年纔開始爆發的。這個例子是自然在人類身上做出選擇的最強和最近的例子。

en Blood

4.黃金血

Although we're often told that type O blood is a universal blood type that anyone can receive, that's not the case. In fact, the whole system is a bit more complicated than many of us realize.

我們都知道O型血是所有人都可以接納的血液，然而這並不是事實。事實上，血液分類的系統比我們所知道的要複雜得多。

While most of us are aware of the eight basic blood types (A, AB, B, and O—each of which can be positive or negative), there are currently 35 known blood group systems, with millions of variations in each system. Blood that doesn't fall into the ABO system is considered rare, and those who have such blood may find it challenging to locate a compatible donor when in need of a l, there's rare blood, and then there's really rare blood. Presently, the most unusual kind of blood is known as "Rh-null." As its name suggests, it doesn't contain any antigens in the Rh system. It's not that uncommon for a person to lack some Rh antigens. For instance, people who don't have the Rh D antigen have "negative" blood (e.g. A-, B-, or O-). Still, it's extremely extraordinary for someone to not have a single Rh antigen. It's so extraordinary, in fact, that researchers have only come across 40 or so individuals on the planet who have Rh-null makes this blood even more interesting is that it totally beats O blood in terms of being a universal donor, since even O-negative blood isn't always compatible with other types of rare negative blood. Rh-null, however, works with nearly any type of blood. This is because, when receiving a transfusion, our bodies will likely reject any blood that contains antigens we don't possess. And since Rh-null blood has zero Rh, A, or B antigens, it can be given to practically everyone. Unfortunately, there are only about nine donors of this blood in the world, so it's only used in extreme situations. Because of its limited supply and enormous value as a potential lifesaver, some doctors have referred to Rh-null as "golden" blood. In some cases, they've even tracked down anonymous donors (a big no-no) to request a e who have the Rh-null type undoubtedly have a bittersweet existence. They know that their blood is literally a lifesaver for others with rare blood, yet if they themselves need blood, their options are limited to the donations of only nine people.

我們都非常瞭解8種基本的血型（A、B、AB、O，每一血型有正負之分），事實是，現在已經發現的血型系統一共有35個，每一個系統又有上百萬種變體。不包括在ABO血型系統的血型被認爲是稀有血型，稀有血型的人會發現當他們需要輸血的時候，要找到一個適配的血型非常困難。在稀有血型之中，還有極其稀有的血型。比如說，Rhnull血型。正如它的名字所顯示的，它在Rh血型中不會產生任何的抗原。某人缺少一些Rh抗原並不奇怪，例如，缺少Rh D抗原的人就是負的血型（A-、B-、O-等）。然而，一個完全沒有Rh抗原的人是特別難以找到的。研究者們在整個地球上都僅僅發現40個左右的人擁有Rh-null血型。Rhnull血型之所以如此吸引人們好奇心的是：它比O型血適配血型還廣，因爲O型血和稀有血型中的負血型並不適配，Rhnull血型卻幾乎能跟所有血型適配。Rhnull血型之所以如此廣泛地適配是有原因的。當接收到輸入的血液時，人體會自動排斥它原本不具有的抗原。Rhnull血型沒有Rh、A、B型抗原，因此它可以被輸送給任何人。不幸的是，整個世界上Rhnull血型的獻血者只有9個人，他們的血液因此也只有在極端情況下才會用到。由於Rhnull血型血液的廣泛適配性以及它可能被作爲拯救生命之血的這種極大潛質，它被某些醫生稱作"黃金血液"。某些時候醫生們甚至會跟蹤匿名的Rhnull血型獻血者以求能採集到一份樣本（當然，這是絕對不可以做的事情）。擁有Rhnull血型的人對於他們自己的血液的感受可以說是喜憂參半。一方面，他們知道自己的血對於別人來說可能是救命神血，但另一方面，如果他們自己病了需要輸血的話，他們能夠指望的也就只有世界上僅存的那九個Rhnull血型的捐獻者。

tal-Clear Underwater Vision

3.在水下擁有水晶般透明的視力

Most animals' eyes are designed for seeing things underwater or in air—not both. The human eye, of course, is adept at seeing things in air. When we try to open our eyes underwater, things look blurry. This is because the water has a similar density to the fluids in our eyes, which limits the amount of refracted light that can pass into the eye. Low refraction equals fuzzy vision.

很多動物的眼睛是被設計來看清在水底或者空氣中的事物的——不能夠兼顧。人類的眼睛擅長於看清空氣中的東西。當我們身處水下，試着睜開眼睛，我們便會發現，眼前模糊不清。這是因爲水的密度與我們眼睛裏液體的密度相當，這限制了眼睛折射光線的數量，從而導致視線模糊不清。

That knowledge makes it all the more surprising that a group of people, known as the Moken, have the ability to see clearly underwater, even at depths up to 22 meters (75 ft). The Moken spend eight months of the year on boats or stilt houses. They only return to land to get essential items, which they acquire by bartering foods or shells collected from the ocean. They gather resources from the sea using traditional methods, which means no modern fishing poles, masks, or diving gear. Children are responsible for collecting food, such as clams or sea cucumbers, from the sea floor. Through this repetitive and consistent task, their eyes are now capable of changing shape when underwater to increase light refraction. Thus, they can easily distinguish between edible clams and ordinary rocks even when many meters below tested, the Moken children had underwater vision twice as sharp as European children. However, it seems that this is an adaptation that we might all possess if our environment demanded it, since researchers have trained European children to perform underwater tasks as successfully as the Moken.

這就使得當我們得知莫肯人能夠在水下（甚至是22米深的水下）將事物看得一清二楚時感到吃驚不已。莫肯人一年中有8個月的時間在船上度過。除了獲取一些必備生活用品之外，他們很少返岸。他們用傳統的方法在海上捕撈。這意味着他們不使用包括釣竿、面具、潛水裝置等一切現代捕魚工具。孩子們負責從海底收集蛤和海蔘等食物。這種工作每日不斷重複，最終使得他們的眼睛在水下具備了可以改變形狀從而增加光反射的能力。因此，他們能夠輕易分別出水下的蛤和石塊，獲取食物。經過試驗，莫肯人孩童的水下視力是歐洲孩童的兩倍。不過，這似乎是每個人都能夠擁有的能力，只要我們改變環境，同樣也會產生相應的變化。研究者們訓練歐洲孩童向莫肯人孩童一樣在水底不停地作業，最終成功地證明了這點。

r-Dense Bones

2.高密度骨骼

Getting old comes with a host of physical problems. A common such issue is osteoporosis, a loss of bone mass and density. This leads to inevitable bone fractures, broken hips, and hunched spines—not a pleasant fate for anyone. Still, it's not all bad news, as a group of people have a unique gene that may hold the secret to curing osteoporosis.

變老伴隨着一系列身體問題。一個常見的問題就是骨質疏鬆症，骨質流失和空隙增大。這將會導致骨折、髖部損壞、駝背等。不過，也不全然是壞消息，因爲有人擁有特殊的基因能夠將其治癒。

The gene is found in the Afrikaner population, and it causes people to gain bone mass throughout their lives instead of losing it. More specifically, it's a mutation in the SOST gene, which controls a protein (sclerostin) that regulates bone growth. If an Afrikaner inherits two copies of the mutated gene, they develop the disorder sclerosteosis, which leads to severe bone overgrowth, gigantism, facial distortion, deafness, and early death. Obviously, that disorder is far worse than osteoporosis. However, if they only inherit one copy of the gene, they don't get sclerosteosis and simply have especially dense bones throughout their ough heterozygous carriers of the gene are currently the only ones enjoying the benefits, researchers are studying the DNA of Afrikaners with hopes of finding ways to reverse osteoporosis and other skeletal disorders in the general population. Based on what they've learned so far, they've already started clinical studies on a sclerostin inhibitor that's capable of stimulating bone formation.

這種基因在阿非利卡人上發現，它使人們在一生中增加骨量而不是失去。確切地說，它是SOST基因變異，這種基因控制着管理骨頭增長的蛋白質。如果阿非利卡人遺傳了兩對突變基因，那麼他們會患上障礙性的硬化性骨化病，這會導致嚴重的骨質增生、巨人症、口眼歪斜、失聰和早逝。很明顯，這個障礙遠比骨質疏鬆症要嚴重。然而，如果他們只是遺傳了一對突變基因，那麼他們不會患上骨質疏鬆症且他們在一生中僅有密質骨。雖然目前僅有該基因的雜合子攜帶者能從中受益，但研究員已經在研究阿非利卡人的DNA，希望能夠找到方法來逆轉骨質疏鬆症和普通人羣中的其它骨骼疾病。基於他們現在所掌握到的，他們已經開始了關於可促進骨形成的硬化蛋白抑制劑的臨牀研究。

Little Sleep

1.睡眠需求減少

If it ever seems like some people have more hours in their day than you do, it turns out they just might—at least more awake hours. That's because there are unusual individuals who can operate on six or fewer hours of shut-eye a night. And they aren't simply getting by—they thrive on this limited amount of sleep, while many of the rest of us are still dragging ourselves out of bed after snoozing for eight solid hours. These people aren't necessarily tougher than the rest of us, and they haven't trained their bodies to function on less sleep. Instead, they have a rare genetic mutation of the gene DEC2, which causes them to physiologically need less sleep than the average normal sleepers were to stick to six or fewer hours of slumber, they'd start experiencing negative impacts almost immediately. Chronic sleep deprivation can even lead to health problems, including serious ones like high blood pressure and heart disease. Those with the DEC2 mutation don't have any of the problems associated with sleep deprivation, despite the limited time their heads are on the pillow. While it might seem odd that a single gene could change what we believe is a basic human need, those studying the DEC2 mutation believe it's helping people to sleep more efficiently with more intense REM states. Apparently, when we have better sleep, we need less of genetic anomaly is exceedingly rare and is only found in less than 1 percent of self-proclaimed short-sleepers. So, chances are, even if you think you have it, you probably don't.

如果有些人的一天似乎比你的要長，那麼他們可能只是有更多醒着的時間。那是因爲有一些獨特的人，他們一個晚上只需要六個小時甚至更少的睡眠時間。他們僅靠有限的睡眠時間就可以維持一天，然而，我們當中的許多人在睡了整整八個小時後仍然要掙扎着將自己拖出牀外。這些人並不是比我們當中的其他人都更頑強，也沒有訓練自己的身體去適應更少的睡眠，而是擁有罕見的突變基因DEC2，這種基因能使他們在生理上比普通人需要更少的睡眠。如果普通人要堅持只睡六個或少於六個小時，那麼他們幾乎是立即就會開始體驗到負面影響。長期的睡眠不足甚至會導致一些健康問題，包括一些嚴重的問題諸如高血壓、心臟病。雖然那些攜帶DEC2突變基因的人睡覺時間有限，但是他們並沒有因爲睡眠缺失而產生任何問題。單基因能夠改變我們所相信的一個人基本的需求，儘管這聽起來似乎很奇怪，然而研究者認爲DEC2幫助人在快速眼動睡眠狀況下睡得更有效率。很顯然，我們睡得越好，我們就越不需要它。這種基因異常極其稀有，僅僅在不到百分之一的自稱短睡眠者身上發現。所以，即使你認爲你有這種基因，你可能並沒有。

翻譯：煙囪、徐杉、歐陽遠麗、阿飯、孟慶潤 來源：前十網