We can predict your chances of living exceptionally long, with 77 percent accuracy, by looking at 150 tiny genetic variants. That’s what researchers claimed in a Science paper that we described last week. Those predictive powers have left some feeling a little uneasy–and not just about what futures are buried in their genomes. Where the paper‘s authors saw correlations, some experts are now seeing errors from DNA testing chips.
No DNA chip is perfect; it can get things wrong as it sorts through hundreds of thousands of genetic variants. In fact, certain chips might even make the same error repeatedly. That could cause problems, because what looks like a genetic variant common to a group of people could instead just be an echoed flaw in one chip’s testing capabilities.
Newsweek, which broke this story, reports that the Boston University researchers who led the study did, in fact, use different chips, but not enough different chips to rule out this potential error. They used two different types of DNA chips to test the centenarian group (about 1,000 people whose ages ranged from 95 to 119): a 370 chip that examines 370,000 genetic variants and a 610-Quad that examines 610,000 variants. The control group (of about 1,200 younger people) was tested with those two chips and a few others, thus possibly hiding any shared errors.
UPDATE: Some experts are questioning the validity of this study, and are suggesting that technical errors skewed the results. Full coverage here.
If you want to know how to get old, it’s best to ask the experts. That’s what Paola Sebastiani, a researcher at Boston University School of Public Health, did; She decided to look at the genes of 1,055 people, many who had already seen their 100th birthday.
As described in a paper published in Science today, Sebastiani’s team found that they could predict a person’s “exceptional longevity” with 77 percent accuracy.
The researchers looked at small variants called single-nucleotide polymorphisms (or SNPs) on the centenarians’ genomes; Sebastiani found she could use 150 SNPs to predict who would live to such exceptional ages.
In a development that’s certain to stir passions in the abortion debate, the Royal College of Obstetricians and Gynaecologists in the UK published a report today on “fetal awareness.” The group states, citing a review of current research, that human fetuses cannot feel pain before 24 weeks.
The group’s reasoning, as described in a press release, is based on these points:
-The fetus cannot feel pain before 24 weeks because the connections in the fetal brain are not fully formed
-The fetus, while in the chemical environment of the womb, is in a state of induced sleep and is unconscious
-Because the 24 week-old fetus has no awareness nor can it feel pain, the use of analgesia is of no benefit
-More research is needed into the short and long-term effects of the use of fetal analgesia post-24 weeks [Royal College of Obstetricians and Gynaecologists]
This is certainly not the first debate over whether a fetus can feel pain. Fetal surgeries have led doctors to ask this question, as they determined whether anesthesia was appropriate and at what stage in development. As summarized in a 2008 New York Times Magazine article, researchers have looked at fetal flinch responses, heart rate, and levels of stress hormones. But any metric has remained controversial. Take stress hormones, for example. Do you say that any fetus that can release these hormones feels pain? Or do you wait until it develops the nervous system to register those hormones? Or do you say that an undeveloped nervous system makes the fetus more susceptible to pain, since it hasn’t developed the system to suppress it?
DNA may dictate your development, but you also wouldn’t be you without the unique mix of bacteria that make their home on your body. This week in the Proceedings of the National Academy of Sciences, researchers say that the very moment of your birth can decide for a lifetime what kind bacteria live in your body, and even whether you’ll be at a higher risk for conditions like asthma.
The uterus is a sterile environment. So, in the womb, babies don’t have any bacteria to call their own. It’s only once they enter the world that they begin to collect the microbes that will colonize their bodies and help shape their immunity [Scientific American].
How babies enter the world is the key, the team says. The studied surveyed the bacterial colonies of 10 mothers just before birth; four of those women gave birth traditionally and six did through cesarean section. When the scientists then checked up on the bacteria living in the newborns, they found that the difference in birth method decided what microbes the baby would get. Those born vaginally tended to pick up the bacteria from their mother’s vagina, while those born via C-section harbored bacterial colonies that tend to come from skin.
The U.S. National Longitudinal Lesbian Family Study, a quarter-century look at the welfare of kids born to lesbian couples, has finally come out in the journal Pediatrics this week with the headline-grabbing finding that those children not only do as well as the rest of the population, they might actually fare better. You can download the paper by lead author Nanette Gartrell for free right now, but here are the key parts:
Select population only
Census data says that there are more than 270,000 American kids in same-sex households, with twice that many having a single gay parent. Gartrell’s study follows a particular slice: Lesbian couples who were together before the child’s birth, identified themselves as a lesbian couple, and went through the artificial insemination process. It didn’t include, for instance, women who may have had a child in a previous heterosexual relationship and then entered into a lesbian one later.
Better than the rest?
The study, which began in 1986, ended up following 78 kids from lesbian couples who were recruited for the study in Boston, Washington D.C., and San Francisco.
The mothers were interviewed during pregnancy or the insemination process, and additionally when the children were 2, 5, 10 and 17 years old. Those children are now 18 to 23 years old. They were interviewed four times as they matured and also completed an online questionnaire at age 17, focusing on their psychological adjustment, peer and family relationships and academic progress [CNN].
The children of these lesbian couples were just as well-adjusted as the kids of heterosexual couples to whom the researchers compared them. Indeed, the kids in the study proved superior in some areas, like academics, self-esteem, and behavior, as shown by the standard “Child Behavior Checklists” that were part of the surveys.
Charles Darwin may have been right in worrying that the ill health that plagued his family were a result of inbreeding. Darwin didn’t only marry his first cousin, Emma Wedgwood–in fact, the Darwins and the Wedgwoods made a habit of intermarrying (Darwin’s maternal grandparents were also third cousins). Now a new study, which crunched the numbers on first-cousin marriages over four generations of the two dynasties, suggests that his children had an elevated risk of health problems.
The degree of inbreeding among Darwin’s children, while not excessive, was enough to increase the risk of recessive diseases — ones that occur if a harmful version of a gene is inherited from both parents. Three of his 10 children died before age 10 — 2 of bacterial diseases. Childhood mortality from bacterial infections is associated with inbreeding. So, too, is infertility, and three of Darwin’s children who had long marriages left no children [The New York Times].
It’s not that teenagers aren’t trying to learn. (Well, OK, some of them definitely aren’t trying.) But the distractions that come with being a teenager are exacerbated by the fact that teens just don’t learn as quickly as either young kids or adults, and a new study of mice that appears in Science points to specific brain changes that might help explain why.
Seeking to study spatial learning during puberty, the team devised a relatively complex task (at least for a mouse) that requires learning how to avoid a moving platform that delivers a very mild shock [TIME]. While the prepubescent mice picked up on what to avoid pretty quickly, as did adult mice, pubescent mice took considerably longer to figure it out. The key to these differences was what study leader Sheryl Smith saw in the brains of these mice.
The Iraq war and its aftermath have left physical and psychic wounds on both local residents who lived through the American invasion and many U.S. soldiers. But anecdotal reports suggest that another demographic may have suffered as well: unborn babies. Doctors in Fallujah, Iraq have reported a high number of children born with birth deformities ever since the massive battle between Iraqi insurgents and U.S. forces that raged there in 2004.
While no medical studies have been done or official reports have been issued, many Fallujah locals suspect that U.S. weaponry used in the assault has left a lingering effect.
A debate is expected to come up in the British parliament sometime next week on the subject. The call for debate came up after the latest report by BBC’s John Simpson, in which an Iraqi pediatrician said she was seeing two to three deformed babies each day; most of the children had cardiac complications. The doctor clarified that while she didn’t have any official figures, she had noted an increase in the number of cases since the American invasion. The current level of cardiac birth defects in Fallujah, said the BBC, is 13 times higher than that in Europe.
Louise Brown, the first baby conceived through in vitro fertilization, will be turning 32 this year, and most people born through IVF are still younger than 30. While the technique has become commonplace for would-be parents struggling with fertility problems, doctors note that the long-term effects of the procedure still aren’t certain. Now, some scientists are saying they see slight differences in the DNA expression of people born via IVF, and that it’s possible they could be at higher risk for conditions like cancer or diabetes later in life.
Says lead researcher Carmen Sapienza said “By and large these children are just fine, it’s not like they have extra arms or extra heads, but they have a small risk of undesirable outcomes” [The Guardian]. Rather, the team found a very subtle impact. In 75 IVF babies and 100 naturally conceived ones, they examined 700 genes that particularly interested the researchers because they are linked to fat cell development, insulin signaling, and other functions associated with diseases for which people tend to be at higher risk as they age. The scientists checked DNA methylation, a modification to DNA which affects gene expression, and found that 5 to 10 percent of IVF babies had abnormal patterns of methylation.
Sapienza’s team published the study in October in Human Molecular Genetics, but his work is picking up attention after he spoke at the American Association of the Advancement of Science meeting in San Diego.