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Entries in Genetics (22)

Thursday
Jun072012

New Baby Genome Mapping to Detect Disorders in the Womb?

Stockbyte/Thinkstock(SEATTLE) -- A new, noninvasive procedure may one day allow women to test their unborn babies for more than 3,500 genetic disorders. It could perhaps replace amniocentesis, in which a probe is inserted through a woman’s abdomen, extracting a small amount of amniotic fluid to test for abnormalities in the fetus.

Scientists at the University of Washington took blood samples of a woman who was 18 weeks pregnant, and saliva from her partner to map the fetus’s DNA. The method was then repeated in another couple.

They then reconstructed the genetic code of the unborn baby, then tested the accuracy of the results by using umbilical cord blood after the baby was born.

“The primary significance of this is that…it may broaden the availability of genetic screening to more patients, while at the same time screening for much larger panels of disorders than can currently be detected,” said Jacob Kitzman, lead author of the study.

The new procedure can test for, among thousands of diseases, spina bifida and Down syndrome, the most common genetic disorders in the U.S., and is safer than amniocentesis.

“This is an incredible breakthrough with huge ethical implications,” said Art Caplan, a professor of medical ethics at University of Pennsylvania Medical Center.

Caplan said today’s amniocentesis testing was relatively “crude,” and new advances would allow more people to obtain reliable genetic information about their children.

Miscarriage is the primary risk of amniocentesis -- the uterus can become infected, the water can break or there’s premature labor.  The risk of miscarriage ranges from one in 400 to one in 200.

About 200,000 amniocentesis procedures are performed every year in the U.S., according to the Mayo Clinic, but “with accurate testing that poses no risk, this new form of genetic testing is likely to be offered to every women and family who is pregnant if the cost is low,” said Caplan.

While researchers said they don’t believe these findings will have an impact on genetic test in a clinical setting in the immediate future, they hope follow-up work will bring technical and methodological improvements that will allow for an easier-to-apply, more accurate and less costly version of the test.

When the time comes for the procedure to be used in a clinical setting though, Kitzman said clinicians would face the challenge of interpreting these results and communicating them with expectant parents -- both the results themselves and the uncertainties that come with them.

While these advances will help better understand risk factors for illness, Caplan predicted “they will be among the most controversial forms of testing ever to appear in medicine as the debate over abortion and disabilities both shift to whole genome genetic testing.”

While the ethical questions that have always surrounded prenatal testing will not disappear with the new procedure, Kitzman said the “noninvasive tests may provide some advantage by posing less potential risk to the fetus.”

"In my experience, full information for parents permits ethical decisions for a family,” said Dr. F. Sessions Cole, professor of pediatrics at Washington University School of Medicine at St. Louis. "A longer term ethical issue concerning the ability to predict disease development in later childhood or adulthood from fetal DNA will also need to be addressed. Hopefully, this new information will prompt development of nutritional, pharmacologic, behavioral, environmental, and other strategies to reduce genetic disease risk.”

Copyright 2012 ABC News Radio

Wednesday
May022012

Pork and Genes: How Pork Smells Genetically Determined, Says Study

iStockphoto/Thinkstock(NEW YORK) -- If you find the smell of pork revolting, it could be because that's how you're genetically programmed to perceive it, according to a new study.

Scientists found that there's a gene responsible for how a compound in pork smells to humans. The gene determines whether pork smells like ammonia, urine and sweat, or if it smells more like vanilla. The compound, androstenone, is similar to testosterone and found in high concentrations in male pigs.

The researchers gave study subjects pork containing androstenone and separated them into two groups -- those who found the smell offensive and those who didn't. Genetic analysis of the subjects revealed that those who didn't like the smell had two copies of a specific form of a gene known as OR7D4. The others had only one copy of the gene.

But, it turns out, most people don't even notice the smell of androstenone.

"In North America and Europe, pigs are castrated, so the concentration of androstenone is quite low," said Hiroaki Matsunami, a co-author and associate professor of molecular genetics and microbiology at Duke University Medical Center. "The only time you find a high concentration of androsteone is when you eat wild boar meat."

That could soon change, however. The researchers noted that the European Union is considering a ban on castration because of concerns over animal welfare, and this debate has rekindled interest in how humans perceive the smell of pork and why two people may smell it differently.

"The data raise the possibility that more consumers will dislike male meat as a result of a castration ban," the authors wrote.

Androstenone is also found in other male animals, but it's found in particularly high amounts in swine, Matsunami said.

How food smells, as everyone knows, also affects how food tastes, and this research helps confirm just how much the nose knows when it comes to taste.

"When food is in your mouth, odors come from the back of the throat up to the nose," said Gary Beauchamp, director of the Monell Chemical Senses Center in Philadelphia. "Taste is very complex. It depends on smell and other factors, such as personal experience and genetic background."

While the study is particularly interesting to scientists, it also demonstrates how genes play a role in many biological processes, including the senses.

"It's a very clear example of how people live in different sensory worlds, and some of the basis of that is our genetic differences," Beauchamp said.

Copyright 2012 ABC News Radio

Thursday
Mar152012

Extreme Gene Testing: One Researcher’s Experience

Comstock/Thinkstock(STANFORD, Calif.) -- When you look at 56-year-old scientist Dr. Michael Snyder, it’s unlikely that “diabetes” would be the first word to come to mind.

“I don’t look like the type of man who has diabetes,” he said. “I have a thin frame and stay active.”

Based on his appearance, most other doctors would agree. However, Snyder’s first-of-its-kind research, through which he subjected himself to frequent lab tests over a period of more than a year, revealed that he did, in fact, have the condition -- and it allowed him to confront it earlier rather than later.

But it also afforded him a rare opportunity: to see the link between his genes and illness play out right before his eyes.

Snyder and colleagues at his lab at Stanford University have spent the past 14 months sequencing his genome -- frequently -- and following the changes in his health. He discovered his personal risk for developing type 2 diabetes, heart disease, a lethal blood disorder and skin cancer.  He saw his genome change in response to viral attacks on his body, including the development of diabetes after catching a respiratory virus from his children.

When Snyder noticed changes in his genome consistent with diabetes, he alerted his personal physician, who was skeptical at first. Laboratory testing, however, revealed an elevation in his blood sugar that lasted several months.

He changed his diet -- cut out sugary desserts, began exercising more frequently, and eventually lost 15 pounds. In his lab, these changes were evident in his genome, and on re-check at his doctor’s office, his diabetes was gone.

Snyder discovered other interesting ways to apply his personal genome monitoring to his own health. He figured out on his own the dosage he needed of his cholesterol-lowering medications based on his personal sequencing of liver proteins. He was able to draft a lineup of dosages for other medications, too, including the anti-diabetes medication he anticipated he needed.

It is easy to see how many in the general public might be interested in emulating Snyder’s approach. However, Dr. F. Sessions Cole from St. Louis Children’s Hospital warns that Dr. Snyder’s response to infection or development of type 2 diabetes may not be appropriate to apply to others -- at least not yet.

“Applicability to the general public will require larger studies to determine patterns,” he said.

For now, Snyder will continue to sequence his own genome regularly, following the hidden changes in real time.  He avoided developing complications from diabetes because of this monitoring. Before his study began, he saw his personal physician once every three years for a check-up.

“If I hadn’t seen the diabetes in my genome,” he said, “I wouldn’t have known it was there.”

Copyright 2012 ABC News Radio

Thursday
Jan122012

First Prostate Cancer Gene Mutation Identified

iStockphoto/Thinkstock(ANN ARBOR, Mich.) -- Simple blood tests offer telling signs of someone’s genetic risk for developing hereditary diseases such as breast cancer. But researchers say they have now identified the first mutation associated with a higher risk of developing prostate cancer.

Researchers analyzed more than 200 genes from 94 men with prostate cancer along with their families. Men within four of the families were found to have a mutation of the gene protein known as HOXB13.

All 18 men within the four families who had prostate cancer also carried the HOXB13 gene mutation, according to the findings which were published Wednesday in the New England Journal of Medicine.

Researchers then compared gene results from nearly 7,000 European men, and found that those with prostate cancer had about 20 times the odds of carrying the mutation compared to men without prostate cancer.

“We found that the mutation was significantly more common in men with a family history and early diagnosis compared with men diagnosed later, after age 55, without a family,” Dr. Kathleen Cooney, professor of internal medicine and urology at the University of Michigan Medical School and study author, said in a public statement.

More than 2 million men are living with prostate cancer, according to the American Cancer Society. Cooney said only a small fraction of men might have this genetic mutation.

HOXB13 gene mutation has previously been linked to progressions in breast and ovarian cancer.  

Many experts say these new findings might turn into the equivalent of the BRCA gene mutation, which can identify a woman’s genetic risk for breast cancer.

But until the findings are replicated in more men with various backgrounds, it’s still too early to tell whether a simple blood test will be able to accurately tell a man’s risk for the disease.

Copyright 2012 ABC News Radio

Wednesday
Jan042012

Oldest Twins in World Celebrate 102nd Birthday

Comstock/Thinkstock(BRECON, Wales) -- The oldest twins in the world had their cake and ate it too when they celebrated their 102nd birthday Wednesday. Ena Pugh and Lily Millward of Wales chalked up their centenarian health to “laughter and a good joke.”

The twins’ families presented the sisters with the most recent edition of the Guinness Book of World Records so they could check out their new entry, according to the UK’s The Sun. Pugh and Millward were born on January 4, 1910, making them the oldest pair on the planet.

Born to farmers in Garthbrengy, near Brecon, Wales, Millward and Pugh were two of 10 children. They are the only siblings still living, and both sisters’ husbands died about 20 years ago. The twins have 15 grandchildren and 12 great-grandchildren between them. The sisters reportedly talk on the phone every day despite both having significant hearing loss, and only recently have their weekly shopping and tea sessions slowed down because Millward broke her hip after a fall.

Nevertheless, the women were together on their birthday, and expressed gratitude for being blessed with happiness and good health.

“We used to work on the farm all day, but we would enjoy ourselves,” Millward told the Wales News Service. “It was a lot of fun and sociable. We’ve been very lucky and we have always had good health.”

But even in an era of complex exercise regimens, perfect diets and juice cleanses, it is genes more than lifestyle that play a major role in whether a person will reach centenarian proportions.

“At higher and higher ages, genetics play a larger and larger role,” said Dr. Alan Shuldiner, director of endocrinology, diabetes and nutrition at University of Maryland. “Many centenarians eat unhealthy diets, smoke, never exercised. I suspect genetics is a large reason why they have lived 204 years between them.”

About 84,000 centenarians live in the United States, and that number is expected to grow to 10 times that by 2050, according to the U.S. Census Bureau. While a study back in 2010 found that genes played a direct effect into a long life expectancy, 30 percent of the centenarians studied had a lifestyle that played a large role in their longevity.

Those lifestyle factors include the ones we should all know by now: exercise, a healthy diet, keeping weight off, not smoking, limiting alcohol, staying social and keeping the cognitive function fresh with reading and crossword puzzles.

Longevity is a complex process, said Dr. Heidi Tissenbaum, professor in the program of gene function and expression at University of Massachusetts Medical School.

“Although there are many that say a positive attitude is good, as well, thus far, studies on centenarians have shown that there is not one environmental factor that stands out,” she said.

“Clearly genetics play an important role and the fact that this is seen in twins confirms that, no less genome sequencing findings,” said Dr. Eric Topol, director of Scripps Translational Science Institute in San Diego. But he notes, “Laughter didn’t get known as the best medicine by accident!”

Copyright 2012 ABC News Radio

Friday
Oct282011

Possible Genetic Marker for Depression Risk Identified

Jupiterimages/Thinkstock(SAN ANTONIO) -- New research has identified a genetic marker that may pinpoint people at high risk for major depression, which scientists say could lead to earlier treatment.

Using blood samples from more than 1,100 Mexican Americans from 40 extended families, researchers at the Texas Biomedical Research Institute in San Antonio and Yale University found an association between a gene called RNF123, which plays a role in the growth of nerve cells, and the risk of major depression. They used a new method that analyzed more than 11,000 different genetic variables.

RNF123 can easily be measured in a person’s blood, which may make it possible to identify people at risk for this debilitating disorder.

“We might be able to know in advance that a person will be less able to respond to the normal challenges that come about in life,” John Blangero, a co-author and director of Texas Biomedical’s AT&T Genomics Computing Center, said in a press release.

While they don’t know exactly how RNF123 may lead to depression, the authors believe it could influence the structure of certain parts of the brain.

Scientists not involved in the study say this is a very promising new approach to zeroing in on how genetic factors manifest themselves in certain disorders.

“There have been a few markers shown to have some relationship to depression, but it’s been really hard to identify specific ones related to major depression,” said Adam Naj of the John P. Hussman Institute for Human Genomics at the University of Miami’s Miller School of Medicine.

Conventional methods of evaluating genetic risk involve comparing the genetic makeup of people who have a certain medical condition to people who don’t, and then going back to try to figure out what effects they have on the body. This type of analysis, Naj said, allows for more detailed identification of genetic factors.

“With this approach, we can try to figure out what the genetic variations may do to features closely related to the disorder,” he said.

Naj also said this method of analyzing heritable factors has been used in research on other conditions, such as cardiovascular disease and diabetes.

Copyright 2011 ABC News Radio

Friday
Oct142011

Battling Breast Cancer at 31

Photodisc/Thinkstock(NEW YORK) -- Tomomi Arikawa said she always knew she would probably get breast cancer. Her mother, Keiko, had discovered the disease when she was 48, and her grandmother had been diagnosed in her 60s.

But when Arikawa discovered a lump in her breast, she was still shocked. She was only 31 years old.

“I thought, maybe they’d find some calcifications on my mammograms when I was 35 or something,” said Arikawa, who is now 32. “But I never thought I’d have a two-centimeter tumor at 31.”

The ABC News story editor told Good Housekeeping that both she and her mother had tested negative for mutations in the BRCA1 and BRCA2 genes, which gives women up to an 80 percent risk of developing breast cancer at some point in their lives. The magazine reported that of the 200,000 U.S. women who get breast cancer each year, fewer than seven percent are under age 40. And only five to 10 percent of new cases are linked to a family history like Arikawa’s.

Her surgeon, Dr. Elisa Port, co-director of the Dubin Breast Center at the Mount Sinai Medical Center in New York City, said although breast cancer patients like Arikawa lack the tell-tale BRCA 1 and 2 mutations, they may have genetic factors leading to breast cancer that simply haven’t been discovered yet.

“Probably in someone like Tomomi, there’s an accumulation of different genetic mutations. We just can’t test for them yet,” Port told Good Housekeeping.

“To be honest, I didn’t worry that I was going to die, because my grandmother and my mom both survived,” Arikawa said. “At that point I wasn’t fearful of death. I just realized I needed to pull it together and make some decisions.”

After talking with her surgeon, Arikawa decided to completely remove her breast with the tumor -- a single mastectomy. Some women with extensive family histories of breast cancer decide to have both breasts remove to lower their risk of ever getting the disease. But Arikawa said she wasn’t ready to make that choice.

“I just couldn’t wrap my head around getting a mastectomy on a breast that had nothing wrong with it,” she said. “For me, maybe it was psychological, trying to hang on to some form of normalcy.”

Because she was so young at the time of her diagnosis, Arikawa faced another complication from the disease. The treatments she would receive might wipe out her ability to have children in the future. Arikawa had to decide if she wanted to preserve some of her eggs before her treatment.

“Not only did I have breast cancer at 31, now I have to think about having children,” Arikawa said.

Initially, Arikawa wasn’t sure she wanted to have children, for fear of passing her breast-cancer genes on to a daughter who might get the disease even earlier in life.

With the advice of her physician, Dr. Port, Arikawa decided to preserve her eggs, as an “extra insurance policy,” in case she ever decided to have children. Treatments can cost thousands of dollars, but Arikawa got financial help from Fertile Hope, an initiative of the LIVESTRONG foundation. A Fertile Hope spokeswoman said women with a cancer diagnosis who make below $75,000 are eligible for financial assistance with egg and embryo freezing and can receive donated medications to help with the treatment.

Today, Arikawa is back to work as a story editor for ABC’s 20/20. She said she would encourage other young women with a family history of breast cancer to find a doctor they can trust with whom they can discuss all aspects of the disease.

Copyright 2011 ABC News Radio

Tuesday
Oct112011

Fruits, Veggies Could Modify Gene Linked to Heart Disease

Jeffrey Hamilton/Thinkstock(HAMILTON, Ontario) -- Eating a healthy amount of greens could have an effect on genes linked to heart disease, according to a new study.

Researchers from Canada's McMaster and McGill universities found that eating fruits and vegetables may actually change a gene variant, called 9p21, that is one of the strongest predictors for heart disease.

"We found that in people with this high-risk gene who consumed a diet rich in vegetables and fruits, their risk came down to that of people who don't have that gene," said Dr. Sonia Anand, a lead author and professor of medicine and epidemiology at the Michael G. DeGroote School of Medicine at McMaster University.

The researchers analyzed the diets of more than 27,000 people from different parts of the world who were already enrolled in two separate studies looking at heart disease.

"Despite having a high genetic risk for heart disease, a healthy lifestyle can actually turn off the gene," said Anand. She also said it's not yet clear exactly how diet affects the gene.

The study participants who lowered their risk through their diet ate at least two servings of fruits and vegetables a day. Raw fruits and vegetables played the biggest role in lowering risk, Anand said.

The role of genetics is an expanding area of medical research, and experts believe the next few years will bring new health recommendations based on people's genetic makeup.

"This points the way toward the future and where we're going in terms of understanding the genetics of heart disease," said Dr. William O'Neill, cardiology professor and executive dean of clinical affairs at the University of Miami's Miller School of Medicine. "Maybe in the next few years, we may be able to do specific gene scans on individual patients and if we find the patients who have genetic high risk, we really want to concentrate on modifying risk by targeting smoking, cholesterol and diet."

And that could be reassuring for many people with genetic susceptibility to certain conditions.

"We often think of genetic factors as being unmodifiable factors," said Anand. "But lifestyle factors can actually change the genes."

Copyright 2011 ABC News Radio

Thursday
Oct062011

Do Thin Parents Pass On Skinny Genes?

Christopher Robbins/Digital Vision(LONDON) -- People with thin parents are more likely to be thin themselves, a new study has found. But don't go chalking up weight woes to bad genes just yet.

Researchers from University College London in the U.K. studied more than 4,400 families with more than 7,000 children. Kids with two thin parents were twice as likely to be thin themselves compared to kids with two parents at the heavy end of a healthy weight range. And kids with overweight or obese parents were progressively less likely to be thin.

"We found evidence of a strong family association, with most thin children and adolescents coming from families in which both parents were thinner than average," the researchers reported in the October issue of Archives of Pediatric and Adolescent Medicine.

Previous studies have uncovered a similar trend at the other end of the scale: kids with overweight or obese parents are more likely to be overweight. Some studies have even implicated specific genes. But experts say genes alone can't explain the drastic rise in obesity over the past 30 years.

"Have our genes changed enough to account for this? Absolutely not," said Dr. David Katz, director of the Yale University Prevention Research Center. "But certain genes could account for the fact that some people are more vulnerable than others."

We share more than just genes with our parents, Katz said, adding behaviors like diet and exercise habits as well as education levels to the list.

"The distinction between nature and nurture in a study like this is absolutely impossible," Katz said. "You can break away from your family pattern if you behave differently than your family did."

Family history can provide helpful insight into risk factors for certain conditions, such as obesity, heart disease and diabetes. But family history is not destiny, Katz said.

"We have a major influence on our medical destiny in how we choose to live every day," he said. "Your genes may make you less vulnerable to weight gain, but anyone can gain weight."

While scientists continue to study the heredity of weight woes, parents can help keep kids on track by setting a good example.

"The example that the parents set and the environment in which you live are very strong determinants of obesity or thinness," said Lisa Cimperman, a registered dietician at UH Case Medical Center in Cleveland. "The sooner we get kids on the path toward eating healthy foods, the more likely they are to carry that on into adulthood."

While genetics do play a role in body weight and shape, they're not the "be-all, end-all," Cimperman said.

"Being healthy is a choice, not something handed to you in your genes," she said, adding that thinness does not necessary go hand-in-hand with health.

Copyright 2011 ABC News Radio

Tuesday
Aug092011

Genetically-Engineered Spermless Mosquitoes Offer Malaria Hope

Stockbyte/Thinkstock(LONDON) -- Where mosquito netting and bug spray fail, European scientists are turning to a unique solution to stem the tide of malaria infection worldwide: they're breeding boy bugs that shoot blanks.

In a study released Monday in the Proceedings of the National Academy of Sciences, researchers in Italy and the U.K. showed they were able to genetically modify male Anopheles mosquitoes so that they wouldn't produce sperm. The bugs would still produce seminal fluid, so mating rituals would go on per usual, but the fruit of coupling would be sterile eggs that don't hatch.

"If mosquitoes [don't] produce any progeny...the number of mosquitoes in the wild will be reduced, eventually reducing the chances of malaria transmission," says study co-author Dr. Flaminia Catteruccia of the Imperial College in London.

Though there are thousands of mosquito species, only a handful of them can transmit malaria, Catteruccia says, so targeting these species has the potential to reduce the spread of disease and is less likely to negatively impact the local ecosystem.

The fact that the Anopheles species of mosquito tends to be monogamous only enhances the effect, as those females who mate with sterile males tended to not seek out other, potentially virile mates.

Sterility may even prove a reproductive boon for spermless males, authors note, because making sperm is energy-consuming, thus the modified males may appear to be stronger mates.

More than 225 million people worldwide suffer from malaria. Each year, nearly 800,000 people will die from the disease -- many of whom are children living in Africa.

"Given the constant spread of the disease, alternative approaches to the use of insecticides are urgently needed," the study's authors wrote.

Monday's research is just the most recent example of a number of mosquito-modifying techniques tested in the past few years in hopes of limiting the mosquito population or the bugs' disease-transmission capabilities.

Other mosquito-limiting tactics have included modifying males to be unable to fly (and who have offspring who also cannot fly) and injecting mosquitos with a special fungus that is thought to reduce the bug's ability to pass malaria to humans, even when the bugs themselves become infected.

The hope with these various methods is that disease rates can be lowered without negatively impacting the surrounding ecosystems, which often include several species of insects and animals that rely on mosquitoes for food.

Copyright 2011 ABC News Radio







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