Friday, July 02, 2010

Will you live to 100? Scientists say it's in your genes

Mega-pesky for the Left. More evidence for them to ignore: It's all due to poverty, I tell you!

EXPLORERS the world over have long sought the fountain of youth, but now researchers claim they have hit upon something tangible: Genetic sequences that can predict whether you'll live to the ripe age of 100.

But don't give up on diet and exercise just yet.

In an early step to understanding the pathways that lead to surviving into old age, researchers report in the online edition of the journal Science that a study of centenarians found most had a number of genetic variations in common.

That doesn't mean there's a quick test to determine who will live long and who won't — a healthy lifestyle and other factors are also significant, noted the team led by Paola Sebastiani and Thomas T. Perls of Boston University.

Nevertheless, Prof Perls said the research might point the way to determining who will be vulnerable to specific diseases sooner, and there may be a possibility, down the road, to help guide therapy for them.

The team looked at the genomes of 1055 Caucasians born between 1890 and 1910 and compared them with 1267 people born later. By studying genetic markers the researchers were able to predict with 77 percent accuracy which came from people over 100. "Seventy-seven percent is very high accuracy for a genetic model," said Dr Sebastiani. "But 23 percent error rate also shows there us a lot that remains to be discovered."

The centenarians could be fitted into 19 groups with different genetic signatures, they found. Some genes correlate with longer survival, others delayed the onset of various age-related diseases such as dementia. "The signatures show different paths of longevity," Sebastiani said.

In general, the centenarians remained in good health longer than average, not developing diseases associated with old age until in their 90s, according to the study.

The researchers were surprised, Dr Sebastiani said, that they found little difference between the centenarians and the control group in genetic variations that predispose people to certain illnesses. "We found that what predisposes to a long life is not lack of disease associated variants, but the presence of protective variants," she said at a briefing.

In addition, 40 percent of "super-centenarians" aged 110 and over had three specific genetic variants in common.

Prof Perls cautioned that this is a very complex genetic puzzle and "we're quite a ways away, still, in understanding what pathways are governed by these genes." "I look at the complexity of this puzzle and feel very strongly that this will not lead to treatments that will get people to be centenarians," he said. But it may help in developing a strategy and screenings that will help find what treatments will be needed down the road.

While this study, begun in 1995, focused on Caucasians, the researchers said they plan to extend it to other groups, including studying Japan, which has large numbers of elderly.

"Inheritability of longevity has been looked at, so genes do play a role," said Dr Kenneth S. Kendler of the Department of Human and Molecular Genetics at Virginia Commonwealth University. But so do other factors "such as driving motorcycles fast and smoking," said Dr Kendler, who was not part of the research team.

The 77 percent accuracy rate reported in this study is better than other groups have been able to do, Dr Kendler added.

The US study found that about 85 percent of people 100 and older are women and 15 percent men. "Men tend to be more susceptible to mortality in age-related diseases," Perls said. "Once they get a disease they more readily die. Women, on the other hand, seem to be better able to handle these diseases, so they tend to have higher levels of disability than men, but they live longer than men."

The study was funded by grants from the National Institute of Aging and the National Heart Lung and Blood Institute of the National Institutes of Health.


Home birth triples neo-natal death risk: study

Although home births are desirable in many ways, it does seem clear that they are riskier

It doesn't appeal to everybody, but for some women, having a good birth means delivering in the peace and familiarity of their own home, far from the white glare and hi-tech wizardry of the hospital.

But a big study in an influential medical journal published today may give them pause. Home birth may be best for the woman, the study finds: she is less likely to have medical intervention, from painkilling drugs to forceps to a caesarean section. But, the researchers claim, it carries three times the risk that her baby will die.

The study in the American Journal of Obstetrics and Gynaecology will inflame passions. But, say the researchers from Maine Medical Centre in Portland, the findings must be addressed. "Women, particularly low-risk parous [having given birth before] individuals, choosing home birth are in large part successful in achieving their goal of delivering with less morbidity [damage] and medical intervention than experienced during hospital-based childbirth," they write.

"Of significant concern, these apparent benefits are associated with a near tripling of the neonatal mortality rate among nonanomalous [without birth defects] infants."

The researchers pulled together data from studies in the US and in Europe. They considered a total of 342,056 planned home births and 207,551 planned hospital births.

The increased death rate was in neonates - babies in the four weeks after delivery. The team found double the number of deaths overall among those born at home and triple the number when they removed those with congenital defects from the calculation. The main causes were breathing problems during birth and failed resuscitation after delivery.

Yet women who choose a home birth tend to be in good health and their babies are less often premature or of low birthweight. "It is especially striking as women planning home births were of similar and often lower obstetric risk than those planning hospital births," they write.

In the developed countries of Europe and the US, they say, after birth defects, oxygen deprivation is the next leading cause of death during or after delivery.

In the past two decades, there has been a marked decrease in babies' deaths because of a lack of oxygen during labour and delivery, they say. "Speculative explanations for the trend include more liberal use of ultrasound, electronic foetal heart rate monitoring, foetal acid-base assessment, labour induction and caesarean delivery," they write.

"Our findings, considered in the light of these observations, raise the question of a link between the increased neonatal mortality among planned home births and the decreased obstetric intervention in this group."

The editors in chief of the journal, Thomas J Garite and Moon H Kim, said the report "supports the safety of planned home birth for the mother, but raises serious concerns about increased risks of home birth for the newborn infant".

"This topic deserves more attention from public health officials," they added.

The president of the Royal College of Obstetricians and Gynaecologists, Professor Sir Sabaratnam Arulkumaran, said there was no clear picture of the relative safety of home births, because it was not possible to conduct randomised trials, where women would be allocated either to give birth at home or on the labour ward.

"The finding that the consequences for the baby are more severe needs to be carefully considered by women, policymakers and care providers," he said. "Certainly, the move towards offering women a choice in their place of birth in the UK needs to be weighed against such evidence."

But he said that a recent study in Scotland had shown that any difference in outcomes for babies disappeared if women considered at high risk of complications during pregnancy and delivery were taken out of the equation. Screening to pick up such women was important, he said, and so were arrangements to get a women to hospital if something went wrong during a home birth. "Mothers should not be alarmed as long as there is a transfer mechanism if there is a difficulty," he said.

He added that it was preferable to have two midwives with good resuscitation skills present at home - one for the woman and another for the baby. Women should also realise that one in three attempting a home birth for the first child ended up being transferred to hospital and one in 10 with a subsequent child - not only because of complications but also for pain relief.

"With the above systems in place and provided women receive one-to-one midwifery care, planned home births for low-risk women are a viable option," he said.

Mary Newburn, head of research at the UK's National Childbirth Trust, said it was "an important study that needs reviewing", but added: "NCT's own detailed review of home birth concluded that, although the quality of comparative evidence on safety of home birth is poor, there is no evidence that for women with a low risk of complications the likelihood of a baby dying during or shortly after labour is any higher if they plan for a home birth compared with planning a hospital birth."


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