คนใบหน้าอ่อน อายุยืนกว่าหน้าแก่

thairath130927_001ผู้ที่เกิดมาเหมือนกับได้รับพรมาให้มีใบหน้าอ่อนกว่าวัย จะมีอายุยืนยาวกว่าคนที่มีใบหน้าแก่กว่าวัยถึงจะเป็นพี่น้องร่วมสายโลหิตเดียวกันก็ตาม

นักวิทยาศาสตร์เดนมาร์กอ้างว่าได้ข้อมูลเหล่านี้มาจากการศึกษากับคู่ฝาแฝดที่มีอายุยืน 70, 80 และ 90 ปี จำนวน 387 คู่ว่า ฝาแฝดคนที่หน้าอ่อนจะมีอายุยืนกว่าฝาแฝดคนที่หน้าแก่กว่า เชื่อว่าอาจจะเป็นเพราะผู้ใบหน้าแก่กว่าได้เผชิญความยากลำบากมามากกว่ากัน จึงได้สะท้อนออกให้เห็นทางใบหน้า

วารสาร  “การแพทย์อังกฤษ” ได้รายงานเบื้องหลังการศึกษาเรื่องนี้ว่า นักวิจัยยังได้รู้สาเหตุของเรื่องว่า เหตุที่ผู้ที่มีใบหน้าอ่อนกว่าวัยมักมีอายุยืนยาวนั้น ขึ้นอยู่กับส่วนปลายของโครโมโซมของสิ่งที่มีชีวิต หากมีหางเหลือยาวก็จะมีอายุยืนยาว ส่วนหางนี้นับว่ามีความสำคัญมาก เพราะนอกจากบอกให้รู้ถึงอัตราความแก่ชราแล้ว มันยังเกี่ยวพันกับโรคภัยต่างๆหลายโรคด้วย.

ที่มา: ไทยรัฐ 27 กันยายน 2556

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People who look young for their age ‘live longer’

People blessed with youthful faces are more likely to live to a ripe old age than those who look more than their years, work shows.

Danish scientists say appearance alone can predict survival, after they studied 387 pairs of twins.

The researchers asked nurses, trainee teachers and peers to guess the age of the twins from mug shots.

Those rated younger-looking tended to outlive their older-looking sibling, the British Medical Journal reports.

Survival advantage

The researchers also found a plausible biological explanation for their results.

Key pieces of DNA called telomeres, which indicate the ability of cells to replicate, are also linked to how young a person looks.

A telomere of shorter length is thought to signify faster ageing and has been linked with a number of diseases.

In the study, the people who looked younger had longer telomeres.

All of the twins were in their 70s, 80s or 90s when they were photographed.

Over a seven-year follow-up the researchers, led by Professor Kaare Christensen of the University of Southern Denmark, found that the bigger the difference in perceived age within a pair, the more likely it was that the older-looking twin died first.

The age, sex and professional background of the assessors made no difference to any of the results.

Professor Christensen said it might be that people who have had a tougher life are more likely to die early – and their life is reflected in their face.

The researchers told the BMJ: “Perceived age, which is widely used by clinicians as a general indication of a patient’s health, is a robust biomarker of ageing that predicts survival among those aged over 70.”

Professor Tim Spector, a UK expert who has been doing his own twin research, said: “We are also finding this in our study.

“It’s probably a combination of genes plus environment over a lifetime that are important.”

He said the findings also show that people are good at assessing how well someone is and that doctors should eyeball their patients.

“If a patient looks older than their years then perhaps they should be more concerned,” he said.

SOURCE : bbc.co.uk

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สงสัยอายุของคนเป็นพ่อเป็นสาเหตุ เด็กทารกที่เกิดมามีปัญหาผิดปกติ

วารสารวิชาการ “ธรรมชาติ” ของอเมริกันแจ้งว่า ได้พบหลักฐานเพิ่มเติมมากขึ้นว่า เด็กทารกที่เกิดมามีปัญหาทางสติปัญญา รวมทั้งเด็กออทิสม์อาจจะเป็นเพราะมีบิดาเป็นผู้มีอายุ

บริษัทด้านพันธุกรรมแห่งหนึ่งในไอซ์แลนด์ พบว่า เด็กที่มีการกลายพันธุ์ทางพันธุกรรมจำนวนหนึ่ง เกิดจากคนเป็นพ่อที่ค่อนข้างจะมีอายุ

ดร.คาริ สเตฟานเซน แห่งสถาบันทางพันธุกรรมศาสตร์ ได้วิจัยได้ผลว่า คนเป็นพ่อที่มีอายุ เป็นเหตุให้ได้ลูกที่มีปัญหาทางสุขภาพ ยิ่งกว่าคนเป็นแม่ เขายังได้แนะนำว่า ผู้ชายที่ยังไม่พร้อมจะมีลูกตอนที่ยังหนุ่มแน่นอยู่ ทางที่ดีควรจะฝากเก็บเชื้ออสุจิของตนไว้ก่อน เพื่อจะได้ใช้เมื่อพร้อมจะมีครอบครัวในภายหลัง.

ที่มา: ไทยรัฐ  30 สิงหาคม 2555

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Fathers bequeath more mutations as they age

 

Genome study may explain links between paternal age and conditions such as autism.

Ewen Callaway
22 August 2012

In the 1930s, the pioneering geneticist J. B. S. Haldane noticed a peculiar inheritance pattern in families with long histories of haemophilia. The faulty mutation responsible for the blood-clotting disorder tended to arise on the X chromosomes that fathers passed to their daughters, rather than on those that mothers passed down. Haldane subsequently proposed1 that children inherit more mutations from their fathers than their mothers, although he acknowledged that “it is difficult to see how this could be proved or disproved for many years to come”.

That year has finally arrived: whole-genome sequencing of dozens of Icelandic families has at last provided the evidence that eluded Haldane. More­over, a study published in Nature finds that the age at which a father sires children determines how many mutations those offspring inherit2. By starting families in their thirties, forties and beyond, men could be increasing the chances that their children will develop autism, schizophrenia and other diseases often linked to new mutations. “The older we are as fathers, the more likely we will pass on our mutations,” says lead author Kári Stefánsson, chief executive of deCODE Genetics in Reykjavik. “The more mutations we pass on, the more likely that one of them is going to be deleterious.”

Haldane, working years before the structure of DNA was determined, was also correct about why fathers pass on more mutations. Sperm is continually being generated by dividing precursor cells, which acquire new mutations with each division. By contrast, women are born with their lifelong complement of egg cells.

Stefánsson, whose company maintains genetic information on most Icelanders, compared the whole-genome sequences of 78 trios of a mother, father and child. The team searched for mutations in the child that were not present in either parent and that must therefore have arisen spontaneously in the egg, sperm or embryo. The paper reports the largest such study of nuclear families so far.

Fathers passed on nearly four times as many new mutations as mothers: on average, 55 versus 14. The father’s age also accounted for nearly all of the variation in the number of new mutations in a child’s genome, with the number of new mutations being passed on rising exponentially with paternal age. A 36-year-old will pass on twice as many mutations to his child as a man of 20, and a 70-year-old eight times as many, Stefánsson’s team estimates.

The researchers estimate that an Icelandic child born in 2011 will harbour 70 new mutations, compared with 60 for a child born in 1980; the average age of fatherhood rose from 28 to 33 over that time.

Most such mutations are harmless, but Stefánsson’s team identified some that studies have linked to conditions such as autism and schizophrenia. The study does not prove that older fathers are more likely than younger ones to pass on disease-associated or other deleterious genes, but that is the strong implication, Stefánsson and other geneticists say.

Previous studies have shown that a child’s risk of being diagnosed with autism increases with the father’s age. And a trio of papers3–5published this year identified dozens of new mutations implicated in autism and found that the mutations were four times more likely to originate on the father’s side than the mother’s.

The results might help to explain the apparent rise in autism spectrum disorder: this year, the US Centers for Disease Control and Prevention in Atlanta, Georgia, reported that one in every 88 American children has now been diagnosed with autism spectrum disorder, a 78% increase since 2007. Better and more inclusive autism diagnoses explain some of this increase, but new mutations are probably also a factor, says Daniel Geschwind, a neuro­biologist at the University of California, Los Angeles. “I think we will find, in places where there are really old dads, higher prevalence of autism.”

However, Mark Daly, a geneticist at Massachusetts General Hospital in Boston who studies autism, says that increasing paternal age is unlikely to account for all of the rise in autism prevalence. He notes that autism is highly heritable, but that most cases are not caused by a single new mutation — so there must be predisposing factors that are inherited from parents but are distinct from the new mutations occurring in sperm.

Historical evidence suggests that older fathers are unlikely to augur a genetic meltdown. Throughout the seventeenth and eighteenth centuries, Icelandic men fathered children at much higher ages than they do today, averaging between 34 and 38. More­over, genetic mutations are the basis for natural selection, Stefánsson points out. “You could argue what is bad for the next generation is good for the future of our species,” he says.

Source: nature.com

พบเทคนิคจับผู้ร้ายไม่มีผิดพลาด

ไม่ว่าจะเป็นโจรใจบาปหยาบช้าอย่างใด ทั้งผู้ร้ายฆ่าคน ผู้ข่มขืนต้องหาคดีข่มขืน หรือโจรกระจอก ต่อไปจะรอดเงื้อมมือของตำรวจได้ยาก เมื่อนักวิทยาศาสตร์ได้พบวิธีสร้างภาพวาดใบหน้า ชั่วแต่เพียงได้เศษเดนของดีเอ็นเอเท่านั้นเอง ทำให้ได้ตัวผู้ต้องหาโดยไม่ผิดตัว ไม่ต้องอาศัยปากคำพยาน ซึ่งอาจจะเชื่อถือไม่ค่อยได้

ความหวังเหล่านี้ เกิดจากที่นักวิจัยเนเธอร์แลนด์ ซึ่งทำงานเกี่ยวกับรูปถ่ายของบุคคลและการถ่ายเอกซเรย์ด้วยคลื่นแม่เหล็กไฟฟ้าสแกนภาพศีรษะ ได้ค้นพบยีนซึ่งกำหนดลักษณะใบหน้าของคน ซึ่งจะช่วยให้ตำรวจสามารถสร้างภาพใบหน้าของผู้ต้องหาได้ง่าย เช่นเดียวกับรอยพิมพ์ลายนิ้วมือ เพื่อที่จะสามารถแจกจ่ายเพื่อให้ช่วยติดตามจับกุม อันจะช่วยยับยั้งไม่ให้ก่อการกระทำผิดขึ้น

นักวิจัยศูนย์แพทย์มหาวิทยาลัยอีรัสมัส ที่เมืองรอตเตอร์ดัม ได้พบว่า มีหน่วยพันธุกรรม 5 ตัว กำหนดลักษณะที่เป็นหลักๆของใบหน้า 9 อย่าง เช่น ตำแหน่งของโหนกแก้ม ระยะห่างระหว่างดวงตา ความสูง ความกว้างยาวของจมูก.

ที่มา: ไทยรัฐ 20 กันยายน 2555

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Scientists used 3D MRI scans to look at various facial landmarks, confirming five genes that are responsible for various face-shape traits. They reported their findings online Sept. 13, 2012, in the journal PLoS Genetics.
CREDIT: PLoS Genetics, doi:10.1371/journal.pgen.1002932

5 Face-Shaping Genes Identified

Trevor Stokes, LiveScience Contributor
Date: 13 September 2012 Time: 05:01 PM ET

Researchers have identified five of the genes that shape a person’s face, work that could help scientists better understand facial abnormalities like cleft palate and someday might even help forensic investigators determine what a criminal suspect looks like from crime-scene DNA.

Researchers previously knew that genetics played a large role in determining face shape, since identical twins share DNA. However, little was known about exactly which genes are involved. Three genes were thought to have roles in the arrangement of facial features, and the new research confirmed their involvement. It also identified two other genes.

“We are marking the beginning of understanding the genetic basis of the human face,” said lead researcher Manfred Kayser, head of the forensic molecular biology department at Erasmus MC-University Medical Center Rotterdam, Netherlands.

SOURCE: livescience.com

พ่ออายุมากกลับสร้างลูกอายุยืนยาว ยิ่งเป็นแบบเดียว 2 ชั้นซ้ำยิ่งดีใหญ่

ผู้ชายที่เป็นพ่อคนเมื่ออายุมาก กลับทำให้ได้ลูกที่มีอายุยืนกว่าปกติ ยิ่งกว่านั้นหากมีปู่ ที่มีลูกเมียตอนเมื่อมีอายุแล้วเข้าด้วย ยิ่งดีใหญ่จะยิ่งได้ลูกหลานที่มีอายุยืนยาวยิ่งขึ้น

วารสาร “สมาคมวิทยาศาสตร์แห่งชาติ” ของสหรัฐฯ รายงานว่า นักวิจัยมหาวิทยาลัยนิวคาสเซิลได้รู้ข้อมูลจากการวิเคราะห์ดีเอ็นเอของหนุ่มฉกรรจ์ 1,779 คน พบว่า องค์ประกอบทางพันธุกรรมของตัวเชื้ออสุจิ ก็จะเปลี่ยนแปรไปตามอายุของเจ้าของ ซึ่งมีผลทำให้อายุยืน และจะถ่ายทอดไปถึงลูกด้วย

ผู้เชี่ยวชาญรู้มานานแล้วว่า อายุขัยขึ้นอยู่กับความยาวของส่วนปลายของโครโมโซม อันเป็นโครงสร้างทางพันธุกรรม ที่เรียกว่า “เทโลเมียร์” มีลักษณะเหมือนกับปลอกพลาสติกหุ้มปลายเชือกผูกรองเท้า ซึ่งจะสึกสั้นลงไปตามอายุ แต่ของตัวอสุจิมันกลับยาวออกไปตามอายุของเจ้าของ ยิ่งในผู้ที่มีพ่อและปู่ ที่มามีลูกเต้าเมื่อมีอายุมากแบบเดียวกันด้วยแล้ว มันจะยิ่งยาวขึ้นไปอีก.

ที่มา: ไทยรัฐ 14 มิถุนายน 2555

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Children with older fathers and grandfathers ‘live longer’

By Michelle RobertsHealth editor, BBC News website
12 June 2012 Last updated at 02:24 GMT

Delaying fatherhood may offer survival advantages, say US scientists who have found children with older fathers and grandfathers appear to be “genetically programmed” to live longer.

The genetic make-up of sperm changes as a man ages and develops DNA code that favours a longer life – a trait he then passes to his children.

The team found the link after analysing the DNA of 1,779 young adults.

Their work appears in Proceedings of the National Academy of Sciences.

Shoelace tips

Experts have known for some time that lifespan is linked to the length of structures known as telomeres that sit at the end of the chromosomes that house our genetic code, DNA. Generally, a shorter telomere length means a shorter life expectancy.

Like the plastic tips on shoelaces, telomeres protect chromosomal ends from damage. But in most cells, they shorten with age until the cells are no longer able to replicate.

However, scientists have discovered that in sperm, telomeres lengthen with age.

Telomeres (in red) cap the ends of chromosomes

And since men pass on their DNA to their children via sperm, these long telomeres can be inherited by the next generation.

Dr Dan Eisenberg and colleagues from the Department of Anthropology at Northwestern University studied telomere inheritance in a group of young people living in the Philippines.

Telomeres, measured in blood samples, were longer in individuals whose fathers were older when they were born.

The telomere lengthening seen with each year that the men delayed fatherhood was equal to the yearly shortening of telomere length that occurs in middle-aged adults.

Telomere lengthening was even greater if the child’s paternal grandfather had also been older when he became a father.


“Very few of the studies that linked telomere length to health in late life have studied the impact, if any, of paternal age”

Prof Thomas von ZglinickiProfessor of Cell Gerontology

Although delaying fatherhood increases the risk of miscarriage, the researchers believe there may be long-term health benefits.

Inheriting longer telomeres will be particularly beneficial for tissues and biological functions that involve rapid cell growth and turnover – such as the immune system, gut and skin – the scientists believe.

And it could have significant implications for general population health.

“As paternal ancestors delay reproduction, longer telomere length will be passed to offspring, which could allow lifespan to be extended as populations survive to reproduce at older ages.”

Prof Thomas von Zglinicki, an expert in cellular ageing at Newcastle University, said more research was needed.

“Very few of the studies that linked telomere length to health in late life have studied the impact, if any, of paternal age. It is still completely unclear whether telomere length at conception (or birth) or rate of telomere loss with age is more important for age-related morbidity and mortality risk in humans.

“The authors did not examine health status in the first generation offspring.”

It might be possible that the advantage of receiving long telomeres from an old father is more than offset by the disadvantage of higher levels of general DNA damage and mutations in sperm, he said.

Data from: bbc.co.uk

แข่งค้นหาความลับ คนอายุยืน 100 ปี ชิงเงินรางวัลมูลค่า 300 ล้านบาท

นักวิทยาศาสตร์จะลงมือแข่งกันค้นหาความลับของการมีอายุยืน 100 ปี ชิงรางวัลมูลค่า 300 ล้านบาท ตั้งแต่เดือนกันยายน ปีหน้านี้

จากความเชื่อที่ว่า ผู้ที่มีอายุยืนจะต้องมียีน หรือหน่วยพันธุกรรมพื้นฐาน ที่มีดีบางอย่าง ช่วยปัดเป่าโรคร้ายในช่วงบั้นปลายของชีวิต อย่างโรคหัวใจและมะเร็งให้พ้นตัวไปได้ โดยการตรวจรหัสหน่วยพันธุกรรมของผู้มีอายุ 100 ปี อาจทำให้นักวิทยาศาสตร์ได้พบวิธีรักษาโรคใหม่ รวมทั้งวิธีทำให้ชีวิตยืนยาวด้วย ซึ่งบรรดามนุษย์วัย 1 ศตวรรษ จำนวน 100 คน ได้พร้อมใจกันบริจาคหน่วยพันธุกรรมของตนให้

ดร.โจนาธาน รอธเบิร์ก นักพันธุกรรมศาสตร์ของบรรษัทเทคโนโลยี ชีวิต ที่รัฐแคลิฟอร์เนีย ชี้ว่า การได้ศึกษาโครงสร้างพันธุกรรมของบรรดาผู้มีอายุถึงรอบศตวรรษ เหล่านี้ นับเป็นการเริ่มต้นที่ดีของการแสวงหา “บ่อชุบตัวของการเป็นหนุ่มเป็นสาว”

มูลนิธิ “เดอ เอกซ์ ไพรส์” ประกาศตั้งรางวัลนี้ขึ้น เพื่อไขปริศนาทางวิทยาศาสตร์ปัจจุบัน  ไม่ว่าจะเรื่องอวกาศไปจนถึงโครงสร้างพันธุกรรมของมนุษย์.

ที่มา: ไทยรัฐ 27 กรกฎาคม 2555

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http://genomics.xprize.org/competition-details/prize-overview

 

Genetic entrepreneur to compete in Genomics X Prize

By Helen BriggsBBC News

24 July 2012 Last updated at 06:28 GMT

A race to unlock genetic clues behind living to 100 is set to begin next year, after a US team announced it will compete for the $10m Genomics X Prize.

Genetic entrepreneur Dr Jonathan Rothberg is entering the challenge to identify genes linked to a long, healthy life.

His team – and any other contenders – will be given 30 days to work out the full DNA code of 100 centenarians at a cost of no more than $1,000 per genome.

The race will start in September 2013.

Under the rules of the Archon Genomics X Prize, teams have until next May to register for the competition.

Dr Rothberg’s team from Life Technologies Corporation in California is the first to formally enter the race.

Being able to sequence the full human genome at a cost of $1,000 or less is regarded as a milestone in science.

It is seen as the threshold at which DNA sequencing technology becomes cheap enough to be used widely in medicine, helping in diagnosis and in matching drugs to a patient’s genetic make-up.


“Start Quote

If they can do a human genome in two hours with one little machine, it’s just stunning. We have come a long way.”

Dr Craig VenterGenetic entrepreneur

One hundred people aged 100 have donated their DNA for the project.

Scientists believe people who reach a very old age may have certain rare changes in their genes which protect against common diseases of later life, such as heart disease and cancer.

If these genes can be identified by analysing the DNA codes of centenarians, it will help scientists search for new medical treatments and perhaps ways to prolong life.

However, many sample DNA sequences will be needed in order to get the accuracy needed to pinpoint changes on the scale of a few genetic letters among the three billion in the human genome.

Dr Jonathan Rothberg, a geneticist and entrepreneur, said the DNA of 100 centenarians is a good start towards finding “the fountains of youth”.

He told BBC News: “One hundred people will give you a hint. One thousand will make you reasonably sure. Ten thousand will let you say, ‘Hey, these are the genes involved in cancer or heart disease'”.

Dr Craig Venter is the originator of the prize and one of the main players in the race to sequence the first human genome, which was completed in 2003.

He said he could never have imagined that genome sequencing would come this far in so little time.

He told the BBC: “I can’t emphasise [enough] how impressed I am with the progress of technology and the dropping of the cost.

“If they can do a human genome in two hours with one little machine, it’s just stunning. We have come a long way.”

The X Prize Foundation offers awards for solutions to modern scientific challenges, from space to the human genome.

Any data gleaned from the X Prize will be shared with other scientists in the field, to aid the quest for insights into ageing.

Dr Jonathan Rothberg

  • Pioneer of DNA sequencing
  • His latest business venture, Ion Torrent, makes the Personal Genome Machine and the Ion Proton sequencer
  • Rothberg claims his machines can sequence DNA more quickly and cheaply than ever thought possible
  • The Ion Proton sequencer will be used for the challenge

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Dr Craig Venter

  • One of the scientists behind the effort to decode the first human genome sequence
  • Venter and his team built the genome of a bacterium from scratch and put it into a cell to make a synthetic life form
  • He has had his own DNA sequence decoded

Data from : bbc.co.uk

Slew of Rare DNA Changes Following Population Explosion May Hold Clues to Common Diseases

ScienceDaily (May 17, 2012) — One-letter switches in the DNA code occur much more frequently in human genomes than anticipated, but are often only found in one or a few individuals.

The abundance of rare variations across the human genome is consistent with the population explosion of the past few thousand years, medical geneticists and evolutionary biologists report in the May 17 advanced online edition ofScience.

“This is a dramatic example of how recent human history has profoundly shaped patterns of genetic variation,” said Joshua Akey, University of Washington associate professor of genome sciences and a senior author of the study. His lab studies the genetic architecture behind differences among humans (as well as among other species) and the mechanisms of evolutionary change.

Although so-called single nucleotide variants are rare, they may influence a person’s resistance or susceptibility to common diseases, like heart or lung trouble or blood problems. The rarity of each specific variation means that scientists will often need to study DNA samples from very large numbers of people to draw any genetic links to these disorders. Researchers already realize that commonly occurring gene variants have only a modest role in the complex medical conditions with the most public health repercussions.

In this week’s paper, “Evolution and Functional Impact of Rare Coding Variations from Deep Sequencing of Exomes,” investigators described their study of the protein-coding sections of genomes from almost 2,440 individuals. The participants were 1,351 people of European extraction and 1,088 of African ancestry.

The study is a first step toward understanding how rare genetic variants contribute to some of the leading chronic illness causes of death in the world. It was conducted as part of the mission of the Seattle GO at the University of Washington and the Broad GO at Harvard University and MIT, both funded by the National Institute of Health’s National Heart Lung and Blood Institute Exome Sequencing Project. The exome consists of the protein-coding regions of the genome.

The overall project encompasses a great many individuals who have distinct traits, such as heart attacks before old age, strokes, or a high body mass index, to discover the genes and molecular mechanisms behind these conditions. Low cost, rapid sequencing of whole genomes is on its way to becoming clinically feasible. The information gleaned would be more useful if statistical and experimental methods could more accurately identify gene variations that regulate biological processes and produce functionally significant proteins. Such methods would link gene variations to disease causes and provide information for preventing and treating diseases.

The other senior author of the paper from the Exome Sequencing Project is Michael J. Bamshad, University of Washington professor of pediatrics in the Division of Genetic Medicine. Researchers from eight institutions across the nation collaborated.

The group sequenced and compared 15,585 human protein-coding genes. They located more than a half-million single-letter DNA code variations in their sample populations. The majority of these variations arose recently in human evolutionary history and so were rare, novel, and specific either to the African or the European study populations, the researchers discovered.

The researchers went on to pick just those single-letter variations in the DNA that might affect the functions of proteins. Alterations in protein functions are among the key ways genetic differences spin into disease traits. They estimated that a little more than 2 percent of the approximately 13,600 single nucleotide variations each person carried, on average, influenced the function of about 313 genes per genome. More than 95 percent of the single-letter code changes predicted to be functionally important were rare in the overall study population.

How did so many rare variations affecting protein function arise in the human genetic code? The researchers suggest that this excess of rare variations is due to a combination of demographic and evolutionary forces. Both European and African populations grew exponentially beginning around 10,000 years ago, but in the past 5,000 years growth rates accelerated leading to the billions of people living today.

The dramatic recent increase in population size has therefore profoundly influenced the spectrum of protein-coding variation present in humans. The scientists calculated the mean average of novel, single-letter code variations in their study subjects: 549 per individual overall. People of African descent had about twice the number of new variations compared to those of European descent, or 762 versus 382.

The researchers measured the effects of natural selection on rare coding variation. To do so, they also brought in genetic details from genes highly specific to humans relative to chimps and macaques to look for what are called “selective sweeps.” A selective sweep occurs when natural selection increases the frequency of a beneficial variant in a population. The beneficial variant doesn’t travel alone. Nearby genetic material is swept along with it. Included among the genes the scientists culled out as affected by positive selection were those related to the sense of smell and to the use of energy.

The researchers also learned that most of the protein-coding variations identified in their study were predicted to be harmful. Rare variation contributes not simply to each individual’s uniqueness, but also to the risk for life-shortening illnesses.

What are the implications of these findings for understanding disease and advancing personalized medicine? Before answering, the researchers pointed to present limitations in robustly identifying functional important gene variation.

“Nevertheless,” they said, “there was considerable rare genetic variation among individuals that is predicted to be functional, which could explain variability in disease risk and in drug response.” The researchers would like more powerful tests to detect the effects of rare genetic variations on human health. They suggest that accounting gene-by-gene might improve research methods. They added that the population-specific nature of most of the single-letter code changes will make it challenging to replicate disease associations with a variant across the world’s people.

Story Source:

The above story is reprinted from materials provided byUniversity of Washington.


Journal Reference:

  1. Jacob A. Tennessen, Abigail W. Bigham, Timothy D. O’Connor, Wenqing Fu, Eimear E. Kenny, Simon Gravel, Sean McGee, Ron Do, Xiaoming Liu, Goo Jun, Hyun Min Kang, Daniel Jordan, Suzanne M. Leal, Stacey Gabriel, Mark J. Rieder, Goncalo Abecasis, David Altshuler, Deborah A. Nickerson, Eric Boerwinkle, Shamil Sunyaev, Carlos D. Bustamante, Michael J. Bamshad, Joshua M. Akey, Broad GO, Seattle GO, and on behalf of the NHLBI Exome Sequencing Project. Evolution and Functional Impact of Rare Coding Variation from Deep Sequencing of Human ExomesScience, 17 May 2012 [ DOI: 10.1126/science.1219240

Data from: sciencedaily.com