科學家發現近視基因 或研製早期預防藥物

Scientists have discovered strands of genetic code linked to short sight, the most common eye disorder in the world.

The findings shed light on what goes awry to make distant objects look blurred, and raises the prospect of developing drugs to prevent the condition.

Understanding the biological glitches behind short-sightedness could help researchers develop eye drops or tablets that could be given to children to stop their vision from failing as they get older.

Short-sightedness, or myopia, usually starts to manifest early on in life.

The extent to which genes are to blame varies, but for those with the worst vision, around 80% of the condition is caused by genetic factors.

Two separate studies, published in Nature Genetics journal, found variations in DNA that were more common in people with short sight. Chris Hammond, at King's College, London, found one section of DNA on chromosome 15 was more common in people with myopia. Caroline Klaver, at Erasmus Medical Centre in Rotterdam, found another strand, also on chromosome 15, linked to short sight.

The variations in DNA amount to misspellings in the genetic code. These alter the activity of three genes that control the growth of the eyeball and ensure light entering the eye is converted into electrical pulses in the retina.

The discovery helps scientists piece together how a healthy eye becomes short-sighted and points the way to medicines to prevent it in children.

"My hope is that we can identify a pathway that we can block with eyedrops or tablets that will stop the eye growing too much and without interfering with normal brain development or other processes in the body," Hammond told the Guardian.

科學家最近發現了一組與近視有關的遺傳密碼。近視是目前世界上最常見的眼部疾患。

這項發現有助於闡明近視的成因，併爲研發預防近視的藥物帶來了希望。

找到近視的生物起因可以幫助研究人員研製出防止兒童視力隨年齡增長不斷下滑的眼藥水或藥劑。

近視往往形成於青少年時期。

對不同的近視患者來說，基因的致病因素所佔比例不同，但對於視力極差的羣體而言，大約80%的病例都是基因導致的。

發表在《自然-遺傳學》期刊上的兩項獨立研究都發現了更常見於近視患者的DNA改變。倫敦大學國王學院的克里斯•哈蒙德發現，15號染色體上的一個DNA片段更常見於近視患者。鹿特丹伊拉斯莫丹醫學中心的卡羅琳•克拉弗發現，15號染色體上的另一段DNA與近視有關。

DNA變化相當於“拼錯”了遺傳密碼，改變了三種基因的活動。這三種基因控制眼球生長、確保眼部所見光線在視網膜轉化爲電脈衝。

這項發現幫助科學家完整理解了健康的眼睛如何患上近視，併爲研製兒童時期預防近視的藥物指明瞭方向。

哈蒙德在接受《衛報》採訪時說：“我希望我們可以找到預防近視的眼藥水或藥劑，防止眼部發育過快，同時不打亂正常的腦部發育或其它身體活動。”

Vocabulary:

myopia: inability to see distant objects clearly because the images are focused in front of the retina; short-sightedness（近視）

chromosome: 染色體

amount to: 相當於

retina: 視網膜

piece together: to make by or as if by joining pieces（拼合，湊集，組合資料以便了解情況）