Why some smokers and non-smokers face higher risk of cancer and other lung diseases

Global probe by more than 100 scientists uncovers 43 new gene variants, which will enable better predictions of those at risk of cancer and illnesses such as emphysema and chronic bronchitis

PUBLISHED : Thursday, 09 February, 2017, 6:00am
UPDATED : Thursday, 09 February, 2017, 6:00am

Scientists have unveiled a trove of newly discovered gene variants to help predict who among both smokers and non-smokers will most likely develop a killer lung disease.

The world’s biggest probe of the genetics of lung health yielded 43 new gene variants linked to chronic obstructive pulmonary disease (COPD), a major cause of death. COPD is a bundle of incurable lung ailments, including emphysema and chronic bronchitis. People with the wrong genetic makeup who also smoke are especially at risk, a team of scientists writes in the journal Nature Genetics.

“As a result of this work, we can now better predict who will develop COPD – opening up the possibility of using this information in prevention,” says Martin Tobin, from the University of Leicester in Britain, one of the leaders of the research team. “This genetic information guides future treatments, including the development of new drugs.”

According to a 2015 study in the Journal of Global Health, there were an estimated 384 million COPD cases globally in 2010. It claimed about 2.9 million lives that year, making it the fourth most common cause of death – and is predicted to reach third place by 2030.

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About 90 per cent of COPD deaths occur in low- and middle-income countries, and some 40 per cent of deaths are attributable to smoking. Despite it being a strong risk factor, not all people who smoke develop COPD, and not all people who do develop it are smokers. This is largely due to genetic differences, said the research team.

By nearly doubling the number of genetic variants associated with lung disease, they discovered that people in the highest genetic risk group were 3.7 times as likely to develop COPD than those in the lowest.

As many as 72 out of 100 smokers in the genetic high-risk group will develop lung disease, the team says.

“By quitting smoking in early adulthood, COPD could be prevented in five out of 10 people [at high genetic risk],” says the University of Leicester study.

“The breakthrough advance could help defuse a ‘ticking time bomb’ for serious lung disease, with over a billion smokers worldwide at risk,” it says.

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Genes are sections of DNA carrying codes for building the proteins an organism needs to function.

Sometimes the same gene varies from one person to the next, accounting for distinct features such as straight or curly hair, eye colour, and vulnerability to diseases.

“Given how common COPD is, we know surprisingly little about the reasons why one individual develops the condition whilst another does not,” says fellow research leader Ian Hall, from the University of Nottingham, also in the UK. “The study of genetic variation between individuals provides a powerful way to understand these mechanisms which underlie disease risk, which in turn will provide a stimulus for drug development.”

The study involved more than 100 scientists trawling through the genetic signatures of 350,000 people from 13 countries.

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Why ‘third-hand’ smoke - residue in smokers’ homes - could be worse than second-hand smoke

The first solid evidence that smoking causes cancer came in the 1950s, followed decades later by revelations that “second-hand” smoke also harms health. Now scientists have issued a warning about what they call “third-hand” smoke – the sticky residue from tobacco puffing that clings to walls and furniture.

In mice, at least, exposure to these toxic leftovers causes lower infant weight and alters counts of blood cells associated with the body’s immune system, they report in the Nature journal Scientific Reports.

“Evidence is mounting that the residue lingering on indoor surfaces could be just as harmful – if not more – than second-hand smoke,” says the Lawrence Berkeley National Laboratory in the United States, which took part in the study.

Researchers from the US and China tested the biological response of mice to third-hand smoke in lab conditions designed to mimic exposure in a smoker’s home.

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Based on what they found, there could be reason to fear for the safety of infants who can pick up toxins from floors and carpets they lie or crawl on, and walls, curtains and furniture they touch, the team said. “Small children are a particularly vulnerable population who are exposed to [third-hand smoke] toxicants through inhalation, ingestion and dermal contact,” they write.

Previous research had shown that these toxins caused DNA damage to human cells in petri dishes, and harmed sperm and the organs of lab mice.

An earlier study of third-hand smoke toxins in house samples warned of a potential cancer risk to children. But it was not known how exposure to them would affect infant health.

For the new study, the team investigated the effects of third-hand smoke exposure on the body weight and immune system of mice in two life stages: from birth to weaning (neonatal), and early adulthood.

Gene therapy breakthrough lets deaf mice hear sounds as quiet as a whisper

Gene therapy delivered by a benign virus enabled deaf lab mice to hear for the first time, researchers say, offering hope for people with genetic hearing impairments.

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The breakthrough could pave the way for gene-based treatments, they report in two studies, published in Nature Biotechnology. “With more than 100 genes already known to cause deafness in humans, there are many patients who may eventually benefit from this technology,” says Konstantina Stankovic, a professor at Harvard Medical School.

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Genetic hearing disorders affect some 125 million people worldwide, according to the World Health Organisation.

In the first study, Stankovic and colleagues used a harmless virus to transport – deep into the mouse ear – a gene that can fix a specific form of hereditary deafness.

Previous attempts had failed, but this time the viral package was delivered to the right address: the so-called outer hair cells that “tune” the inner ear to sound waves.

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“Outer hair cells amplify sound, allowing inner hair cells to send a stronger signal to the brain,” says Gwenaelle Geleoc, a researcher at the F.M. Kirby Neurobiology Center at Boston Children’s Hospital in the US. The technique bestowed hearing and balance “to a level that’s never been achieved before”, she says. “Now you can whisper, and the mice can hear you.”

In the second study, a team led by Geleoc used the same viral courier to treat mice with a mutated gene responsible for Usher syndrome, a rare childhood genetic disease that causes deafness, loss of balance, and in some cases blindness.

The virus carried a normal version of the same gene to damaged ear hair cells soon after the mice were born. The results far exceeded anything to date: 19 of 25 treated mice heard sounds quieter than 80 decibels. Normal human conversation is about 70 decibels.

A few of the mice could hear sounds as soft as 25 to 30 decibels – roughly equivalent to whispering.