Category Archives: Human Genetics

By Elizabeth PennisiJul. 19, 2017 , 2:00 PM

Its one of the biggest perks of being a dog owner: Your pooch is thrilled when you come home, wagging itstail, wiggling itsbody, and licking you with itstongue. Now, scientists say they have pinned down the genetic basis of this affection. Using clues from humans with a genetic disorder that makes them unusually friendly, the team found variations in several genes that make dogs more affable than wolves and some dogs friendlier than others.

The study shows that the genetics of dog behavior might be even more relevant for understanding genetics of human behavior than we once thought, says Per Jensen, a behavioral geneticist from Linkping University in Sweden who was not involved with the research.

Over the past decade, geneticists have discovered the DNA involved in key dog traits, such as size and coat variation. Some DNA seems linked to personality, and one study showed that dogs and humans enforce their bonds by gazing at each other. But few studies have pinned particular behaviors to specific genes. Theres been a remarkable explosion of studies, with the exception of behavioral studies, says Robert Wayne, an evolutionary biologist at the University of California, Los Angeles, who was not involved with the work.

Seven years ago, Monique Udell, an animal behaviorist at Oregon State University in Corvallis,and Princeton University geneticist Bridgett vonHoldt joined forces to link genes to a behavioral trait they think was pivotal to dog domestication: hypersociability. Researchers already know that dogs are hypersocial compared withwolves, and the team confirmed this by comparing the behavior of 18 dogssome purebreds, others mixed breedswith10 captive, hand-raised wolves at a research and education institute in Indiana. As others had shown, the dogs were much friendlier than the wolves, even though the wolves had been raised by people. Both hand-raised wolves and dogs greet human visitors, but dogs continue to interact with people much longer than wolves do, even when visited by a stranger.

The researchers then turned to humans with Williams-Beuren syndrome, a developmental disorder that leads to mental disability and an elfin appearance, but also often makes a person very trusting and friendly. The syndrome results from the loss of part of chromosome 7. VonHoldt focused on this stretch of DNA because she previously had found that this region, which is on dog chromosome 6, seemed to havebeen important in canine evolution. It was a long shot, says Wayne, but VonHoldt decided to see whetherthis DNA was responsible for dogs friendliness.

The DNA varied widely in both dogs, and to a lesser degree, wolves, with parts inserted, deleted, or duplicated. Almost every dog and wolf we sequenced had a different change, VonHoldt says. People with Williams-Beuren also show great variation in this region, and the variation is thought to affect the severity of the disease and peoples personalities.

The same seems true in the wolves and dogs. Hypersocial dogs had more DNA disruptions than the more aloof wolves, the team reports today in Science Advances. Disruption on a gene for a protein called GIF21, which regulates the activity of other genes, was associated with the most social dogs. A relative lack of changes in that gene seems to lead to aloof, wolflike behavior, VonHoldt says. Changes in that gene in mice cause that species to be hypersocial as well. Two other genes also were linked to sociality in dogs.

Were almost describing variation in personality, in the animals, VonHoldt explains. She and Ubell did not study enough purebred dogs to draw any conclusions about how these variations might influence breed personalities, however.

The study is exciting because it provides such strong support for the survival of the friendliest hypothesis of dog domestication, says Brian Hare, an evolutionary anthropologist at Duke University in Durham, North Carolina, who was not involved in the work. In ancient wolves with these gene disruptions fear was replaced by friendliness and a new social partner [was] created.

In a sense, this is the first paper discovering the genes related to the high sociability of dogs, says Takefumi Kikusui, an animal behaviorist at Azabu University in Sagamihara, Japan, also not involved with the work. Humans too have high sociability relative to other primates. Probably, these two species, namely human and dogs, use the same genes for these social behaviors.

However, some experts think the study needs to be expanded to more dogs and wolves to be sure of the conclusions. With so few individuals the associations are at most suggestive at this point, Jensen says. Kikusui suggests they look for this gene-behavior connection in other populations of dogs and more individuals.

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What makes dogs so friendly? Study finds genetic link to super-outgoing people - Science Magazine

The American Society of Human Genetics has awarded OU Childrens Physicians Geneticist John J. Mulvihill, M.D., of Edmond, its 2017 Mentorship Award. Mulvihill holds the Childrens Hospital Foundations Kimberly V. Talley Chair in Genetics and is also a professor of Pediatrics at the University of Oklahoma College of Medicine.

He is also a senior consultant to the division of Genomic Medicine in the National Human Genome Research Institute, part of the National Institutes of Health.

The ASHG Mentorship Award recognizes members who have significant records of accomplishment as mentors. It is open to individuals at all academic ranks who have shown a sustained pattern of exemplary mentorship at the graduate, postdoctoral, residency or fellowship level. The award presentation, which includes a plaque and $10,000 prize, will take place on Friday, Oct. 20, during the organizations 67th Annual Meeting in Orlando, Fla.

Its an incredible honor for me to accept this recognition from my colleagues and outstanding mentees, whose careers and lives Ive been privileged to touch, Mulvihill said. Mentorship in genetics, science and medicine is a life-long duty and joy.

Over the years, Mulvihill has founded multiple successful genetics training programs across the country, and has personally mentored trainees across fields and career stages through these programs. In 1983, while serving as clinical genetics section chief in the National Cancer Institutes Clinical Epidemiology Branch, he helped launch the NIH Interinstitute Medical Genetics Training Program, which he directed until 1989. He then founded the department of Human Genetics at the University of Pittsburgh, where he served as professor and co-director of the Pittsburgh Genetics Institute until 1998.

That same year, he founded the section of Pediatric Genetics at the OU College of Medicine, where he later established the Medical Genetics Residency Program and the masters program in Genetic Counseling. His research has focused on the genetics of human cancer, particularly late genetic and reproductive effects in cancer survivors and germ cell mutagenesis.

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Edmond geneticist earns National Mentorship Award - Edmond Sun

Centre Daily Times

Boalsburg native's website teaches cooking skills to people with disabilities Centre Daily Times Moyer is in the process of earning a doctoral degree in human genetics at Johns Hopkins University, which will one day look great on a wall somewhere next to her master's degree in biology. Home dcor aside, Moyer hopes to use her studies to better ...

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Boalsburg native's website teaches cooking skills to people with disabilities - Centre Daily Times

When two peoplewith a rare form of deafnessmate, the genetic combination can yieldan unusual syndrome in which the child hasfragile bones, deafness, blindness and albinism. Therecently-discovered syndrome is known as COMMAD, for coloboma (ocular holes), osteopetrosis (note the suffix dense bones), microphtalmia (small eyes), macrocephaly (large head), albinism, and deafness.

This new discovery was made by Aman George and colleagues at the Ophthalmic Genetics and Visual Function Branch of theNational Eye Institute. Theydemonstrated that with a combinatorial effect of certain genotypes from both parents, this exceedingly rare set of occurrences in the child is one possible outcome. Of course, as with any mating event, there are many possible outcomes.

The disorder is an example of a raredisease passedon by parents who do notexhibit the condition. It occursthrough genetic combination and mathematical permutation (as autosomal recessive inheritance). Two children were identified with the COMMAD syndrome, and each has two different recessive mutations of the gene that codes for microphthalmia-associated transcription factor (MITF). The research report was published inthe American Journal of Human Genetics.

What had been previously known about MITF was limited, but that mice with two recessive mutations in the MITF gene had impairments in their osteoclasts (bone degradation cells), mast cells (a type of immune cell), retinal pigment, and melanocytes (pigment-producing cells of the skin). Beyond the mice research, human cases were unknown prior to this work and these two cases. In vitro cell experiments (within flasks) using zebrafish embryos showed that the abnormal MITF protein could not enter cell nuclei or bind DNA, and it impaired melanocyte migration, differentiation, and survivability which is a strong supportive causal factorfor the albinism seen in the two human cases. Similarly, the eye abnormalities also could occur because of the MITF mutations on the retinal pigment epithelium, causing ophthalmic disorder. This is due in large part because of the powerful role the retinal pigment epithelium (RPE) plays in eyehealth and maintenance.

The retinal pigment epithelium is a single layer of cells overlying the retina, just underneath the photoreceptive layer of cells. The RPE expresses certain proteins that regulate the transport of nutrients (to) and waste (away from) the retina. It also helps to continuously renew ocular precision by ingesting and degrading the worn out terminal ends of the photoreceptor outer pieces, keeping vision sharp.It also acts as a physical barrier to the retina against high-energy light as well as oxygen reactive species created from photodegradation of molecules. MITF mutations leading to RPE abnormalities can significantly compromise these structures required for proper function and homeostasis within the eye.

In order to mitigate future occurrences of this particular spectrum of rare diseases, the researchers advise genetic testing in particular cases with couples where Waardenburg syndrome type 2A (WS2A) or Tietz syndrome may be present (and/or if both parents have partial albinism and hearing loss, which could be an indicator), as well as genetic counseling about the risks to offspring if it is indeed a potential factor.Waardenburg syndrome type 2 is usually inherited in an autosomal dominant manner.This means that having a mutation in only one copy of the responsible gene in each cell is enough to cause features of the condition.

When a person with a mutation that causes an autosomal dominant condition has children, each child has a 50% (1 in 2) chance to inherit that mutation. In other cases, the mutation occurs for the first time in a person with no family history of the condition. This is called a de novomutation.Whats interesting about COMMAD is that it is a disease associated with one gene, and it has a different mode of inheritance from both WS2A and Tietz syndrome, which are both autosomal dominant.Identifying the gene responsible for WS2 is necessary to determine the subtype that is present in a person or family.

The children in the particular cases inherited different recessive mutations from each parent, yet the parents have the same autosomal dominant condition, but didnt know it. The parents and children in the two cases each have Waardenburg syndrome type 2A, with very white complexions, blue eyes, premature graying, and profound sensorineural hearing loss. Some of the siblings of the two cases are fair and deaf like the parents.In some instances, an affected person inherits the mutated gene from an affected parent.

People with questions about genetic risks or genetic testing for themselves or family members should speak with a genetics counselor about their options. Typical steps in the process are:

Ben Locwin is a behavioral neuroscientist and astrophysicist with a masters in business, and a researcher on the genetics of human disease. Follow him on Twitter @BenLocwin.

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Rare genetic diseases can arise from unsuspecting carriers - Genetic Literacy Project

China's Dr Frankensteins are 'on a path to eugenics' as they tinker with the genetic code of animals - and we could be next

CHINESE scientists who are cloning canines to create mutated superdogs are on the road to eugenics, a top genetics expert has warned.

The pups, like the one below, are being bred to become stronger and faster and could be used for security or policing.

Sino Gene

Experts at Sino Gene, a biotech company based in Beijing recently revealed afluffy beagle called Long Long to the world.

It is the first of his kind because it has been cloned from a genetically modified parent, they claimed.

The pup arrived in late May in a Sino Gene lab, exactly where her dad was born in December last year.

But despite its adorable appearance, a British genetics expert said he is very concerned about how the scientists are using genetics for non-medical purposes.

Scientists genetically modify animals in the UK to test medicines like cancer treatments on mice, rabbits or dogs.

David King, director of Human Genetics Alert (HGA), warned that this was the first step to creating mutant children.

Asia Wire

Its true that the more and more animals that are genetically engineered using these techniques bring us closer to the possibility of genetic engineering of humans.

Dogs as a species, in respect of cloning, are very difficult and even more difficult to clone human beings.

Theres no medical case for it, the scientists are interested in being the first person in the world to create a genetically-engineered child.

Theyre interested in science and the technology and their careers. They will continue pushing the regulations for it.

Asia Wire

Eyevine

That does set us on the road to eugenics. I am very concerned with what Im seeing, he told the Express.co.uk.

Lai Liangxue, a researcher at the Guangzhou Institute of biological medicine and health, told China Plusthat the birth of Long Long put China on the map.

He said: This is a breakthrough, marking China as only the second country in the world to independently master dog-somatic clone technology, after South Korea.

With this technology, by selecting a certain gene of the dog, we can breed an animal with more muscles, a better sense of smell and stronger running ability, which is good for hunting and police applications.

Liangxue has already created the worlds first gene-edited dogs. beagles named Hercules and Tiangou.

They double the amount of muscle mass of a typical dog of its breed by deleting a gene called myostatin.

The dogs have more muscles and are expected to have stronger runningability,which is good for hunting, police (military) applications, Liangxue told MIT review back in 2015.

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Chinese scientists who made muscly 'super dog' could create genetically-modified human CHILDREN next' - The Sun

The dogs, which are test tube bred in a lab, have twice the muscle mass of their natural counterparts and are considerably stronger and faster.

The canine genome has been especially difficult to engineer and replicate but its close similarity to the human genome means it has long been the prize of geneticists.

Now the Chinese success has led to fears the same technology could be used to create weaponised super-humans - typifed in Marvel Comics by Captain America and his foes.

MARVELEYEVINE

David King, director of Human Genetics Alert (HGA), voiced his fears over what is widely viewed as the first step on a slippery slope.

He told express.co.uk: Its true that the more and more animals that are genetically engineered using these techniques brings us closer to the possibility of genetic engineering of humans.

Dogs as a species, in respect of cloning are very difficult, and even more difficult to clone human beings.

Theres no medical case for it, the scientists are interested in being the first person in the world to create a genetically engineer child.

In terms of genetic engineering we will be seeing this more and more

David King, director of Human Genetics Alert

Theyre interested in science and the technology and their careers. They will continue pushing the regulations for it.

That does set us on the road to eugenics. I am very concerned with what Im seeing.

An army of super-humans has been a staple of science fiction and superhero comics for decades but the super-dog technology brings it closer to reality.

The Chinese researchers first self-bred cloned dog was named Little Long Long.

SINO GENE

The beagle puppy, one of 27, was genetically engineered by deleting a gene called myostatin, giving it double the muscle mass of a normal beagle.

The advance genetic editing technology has been touted as a breakthrough which could herald the dawn of superbreeds, which could be stronger, faster, better at running and hunting.

The Chinese official line is that the dogs could potentially be deployed to frontline service to assist police officers.

Dr Lai Liangxue, researcher at Guangzhou institute of biological medicine and health, said: "This is a breakthrough, marking China as only the second country in the world to independently master dog-somatic clone technology, after South Korea."

VCG via Getty Images

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Armed police soldiers lift timbers during a drill on August 24, 2016 in Chongqing, China. As the highest temperatures reached over 40 degree Celsius at 5 districts in Chongqing, officers and soldiers of an armed police crop took outdoor training

Some 65 embryos were edited, and from that 27 were born, with Little Long Long the only one who was created without the myostatin gene. Myostatin is known to control muscle size in humans.

Dogs are one of the hardest animals to clone, with only South Korea thought to have successfully created a clone in the past.

As well as the enhancements, researchers said in the Journal of Molecular Cell Biology some dogs will be bred with DNA mutations in a bid to help medical research, including some which mimic Parkinsons.

Dr Lai added: "The goal of the research is to explore an approach to the generation of the new disease dog models for biomedical research.

GETTY

"Dogs are very close to humans in terms of metabolic, physiological and anatomical characteristics."

But some have criticised the experiments, citing ethical concerns.

Mr King said: This is the way its likely to proceed if the law is changed, first of all they will use it for medical purposes, most likely to treat a genetic condition.

In terms of genetic engineering we will be seeing this more and more.

There are also fears that, as well as medical, tinkering with genetics could also lead to a rise in designer or novelty pets.

Dr Lai said his team have no intentions to breed the bulked up beagles as pets.

But Mr King also voiced fears that this breakthrough, coupled with existing cases of altering human embryos, could lead to further calls for designer babies.

The director of HGA, and independent body, claimed there are multiple examples of eugenics going on already, citing women who are intelligent and beautiful are paid more for their eggs in the US.

Mr King said: Its not scaremongering.

Im seeing the beginning of a campaign within the scientific community to legalise human genetic engineering.

Weve seen how it happened with the thee-parent embryo.

SINO GENE

I can see the same thing building up with genetic engineering.

There are strict laws around cloning, but one example of a case in the UK is Dolly the sheep.

Born in 1996, she died aged six in 2003, half the normal life span of a Finn Dorset sheep.

And recently, an artificial womb for premature babies was tested on lambs, and showed significant success.

Lambs born at the equivalent of 23 weeks were placed inside the fake womb which contained fluid mimicking that found in an amniotic sac.

They remained inside for 28 days, and continued to develop, even growing white fleeces.

Guo Longpeng, the China press officer for the Asia division of People for the Ethical Treatment of Animals, said: "Cloning is unethical.

"Like any other laboratory animal, these animals are caged and manipulated in order to provide a lucrative bottom line."

Link:
China unveils gene technology to create SUPERHUMANS with hyper-muscular test-tube dogs - Express.co.uk

From Staff Reports Published: July 16, 2017 5:00 AM CDT Updated: July 16, 2017 5:00 AM CDT

John Mulvihill, M.D., at The Children's Hospital at OU Medical Center, has won a mentorship award from theAmerican Society of Human Genetics. [Photo provided]

Geneticist wins national recognition

John Mulvihill, an geneticist at The Children's Hospital at OU Medical Center, has been awarded the American Society of Human Genetics mentorship award. The award recognizes those with records of accomplishments as mentors. He will receive the $10,000 award at the national group's annual meeting on Oct. 20 in Orlando, Florida.

Back-to-school shots available

The Oklahoma City-County Health Department is offering back-to-school immunizations for students at three locations across Oklahoma City. Immunizations will be offered Monday through Thursday from 8 a.m. to 4 p.m. and 8 a.m. to noon on Friday. A copy of the students immunization records is required. Immunization services will be offered at:

Gary Cox Partner Building, 2700 NE 63

South Wellness Campus, 2149 SW 59, Suite 104

West Clinic, 4330 NW 10

Birth certificates needed for school

The Oklahoma State Department of Health is urging families to begin requesting birth certificates as they prepare to send their children back to school. The busiest month of the year for requests is August and long lines are normal. The cost is $15 for a copy. Information can be found online at http://vr.health.ok.gov.

Mumps still a problem in state

Kristy Bradley, state epidemiologist, confirmed that the state is still facing a problem with mumps. Oklahoma and Garfield counties are still seeing cases of mumps transmission. The state has had 152 cases since January.

From staff reports

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Oklahoma medical briefs, July 16 - NewsOK.com

The premise behind Yes or No Genomics is simple: Genetic disease is typically caused by a variation in at least one of the many thousands of genes in the human genome, so knowing whether your DNA code contains variants could suggest whether your health is at risk. And for just $199, the scientists at Yes or No Genomics can use special technology to determine that.

Except Yes or No Genomics isnt a real company. Its satire.

The mind behind this parody is Stanford geneticist Stephen Montgomery, who hopes the website he launched this week will highlight the extreme absurdity of many of the scientific consumer genetic tests now on the market. Fork over $199 to Yes or No Genomics, and you will find out, inevitably, that you do have genetic variants, because everyone does. And that specialized optical instrument used to determine this? A kaleidoscope.

Montgomery is one of a growing number of scientists pushing back against wild claims in the consumer genetics market, which is flush with tests promising to plumb the secrets of our DNA for answers to everything from what kind of wine well enjoy to what diseases were at risk of developing. These tests vary wildly in levels of absurdity. One test that recently earned eye-rolls promises to improve a childs soccer abilities with a personalized, genetics-based training regimen. In case its not clear, there is still no way to decode from DNA the perfect plan to turn your 7-year-old into a soccer star.

Clearly, there is a whole world of companies that are trying to take advantage of people, Montgomery told Gizmodo. Sports, health advice, nutrition...companies are coming out saying, We can look at your DNA and tell you what you should be doing. Really, though, were still trying to understand the basics of genetic architecture. We need to help people avoid getting caught in these genetic traps.

In the wake of that ridiculous Soccer Genomics test, Montgomerys parody site went viral among those who closely follow genetics developments on the web. And he isnt the only researcher who has realized that combatting psuedoscience in the annals of academic journals isnt enough.

For years, Daniel MacArthur, a geneticist at the Broad Institute, ran a blog dedicated in part to exposing bad science in the realm of genetics. Like many scientists, he now uses Twitter to call attention to bogus tests. Other reliable Twitter crusaders include UCLA geneticist Leonid Kruglyak, health policy expert Timothy Caufield, and CalTech computational biologist Lior Pachter. For every new pseudoscientific DNA test, it seems more voices join the chorus.

Its a pretty exciting time to be in genetics. Theres a lot happening, MacArthur told Gizmodo. But that also makes it really easy for people who dont know anything about genetics to enter the consumer market.

Plenty of the tests out there, MacArthur said, are relatively harmless. Finding out which wine youre genetically likely to enjoy probably isnt going to hurt much more than your wallet. But thats not always the case. MacArthur pointed to a simple genetic test that claimed it could detect autism, which he and his colleagues spoke out about after finding out the test had a patent in the works.

We were very confidant that the variants they were testing for had no relationship to autism, he said.

Genetics comes with this veneer of respectability and the public automatically thinks anything with the word genetics is trustworthy and scientific, he continued. It just isnt possible that there is a useful predictive test for soccer. For academics its easy to see that. But who is responsible for going out there and pushing back? Thats less clear.

In 2008, an European Journal of Human Geneticsarticleargued for better regulatory control of direct-to-consumer genetic testing, pointing out that many of these tests run the risk of being little better than horoscopes.

In rare cases, the Food and Drug Administration has stepped in. In 2013, it cracked down on 23andMe, ordering the company to cease providing analyses of peoples risk factors for disease until the tests accuracy could be validated. After gaining FDA approval, the company now provides assessments and risk factors on a small fraction of 254 diseases and conditions it once scanned for.

But the FDA has steered away from policing smaller, fringe companies like, say, those offering advice on your skin, diet, fitness and what super power you are most likely to possess. Some companies the FDA likely does not even have authority to police, since not all of them can be considered medical interventions.

Its kind of distressing to see [the FDA] go after 23andMe rather than companies that are lower profile, but doing science that is flatly incorrect, said MacArthur. What I would love to see would be an organization like the Federal Trade Commission really step in and take much more responsibility. Historically that just really hasnt happened.

Another thing MacArthur would like to see is companies list the scientific data underlying their claims. If consumers could easily see, for example, that the recommendation to drink apple juice from the company DNA Lifestyle Coach stemmed from a study of just 68 non-smoking men, they might more readily deduce how valid such a recommendation is.

Inspired by satirists like Stephen Colbert, Montgomery is interested in how effective parody might be as a tool to combat bad science. Ive gotten a lot of good reaction to the website, he said. I want to see how far can we take this as a joke.

But more than anything, he wants consumers to be wary of the ever-growing number salesmen peddling genetic snake oil.

We want people to understand which tests are actually useful, he said. People should be empowered in how they use this data.

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Scientists Push Back Against Booming Genetic Pseudoscience Market - Gizmodo

People in the News: Kri Stefnsson, Arthur Beaudet, and Mary Thistle GenomeWeb The American Society of Human Genetics has named Kri Stefnsson the winner of this year's William Allan Award, a prize established in 1961 that recognizes a scientist for "substantial and far-reaching scientific contributions to human genetics ...

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People in the News: Kri Stefnsson, Arthur Beaudet, and Mary Thistle - GenomeWeb

Researchers are always looking for new clues to the causes of autism, with special emphasis on prevention or treatment. At Baylor College of Medicine, Dr. Arthur Beaudet has been following clinical and genetic clues in patients with autism spectrum disorder and experimental results in animal models that have led him to propose that the lack of carnitine, a nutrient needed for the normal development and workings of the brain, the liver, the heart and other muscles, might be involved in triggering mild forms of autism.

In a publication in the journal BioEssays, Beaudet, the Henry and Emma Meyer Chair and Professor of Molecular and Human Genetics, emphasizes that more research is needed to confirm this idea and speculates that, if confirmed, it could lead to the prevention of 10 to 20 percent of cases of autism by supplementing carnitine to infants.

In the Beaudet lab, graduate student Patricia Celestino-Soper discovered in 2009 that about 1 in 350 males in the population cannot synthesize their own carnitine; they have an inactive copy of the TMLHE gene, which is located on the X chromosome.

Of the nearly 460,000 males in the United States who have TMLHE gene deficiency, only about 3 percent develop autism. The remaining 97 percent become healthy adults, Beaudet said. Sometimes behavioral regression occurs.

The regression of skills might be as subtle as first having a social smile and playfulness at 6 to 8 months of age and then losing these skills. Sometimes, the regression of skills occurs later and is more dramatic. Although TMLHE deficiency is present in only about 1 percent of autism cases, Beaudet proposes that carnitine deficiency in the brain might cause a much larger fraction of autism.

We speculate that the individuals with a normal physical examination and normal brain imaging results in studies, which represents 10 to 20 percent of all cases of autism spectrum disorders, might have in common a mechanism that leads to a mild form of autism. This mechanism might involve brain carnitine deficiency, Beaudet said.

In the search for more evidence to support the link between carnitine deficiency and mild forms of autism that disproportionally affect males, Beaudet and colleagues looked for other genes on the X chromosome that might be involved with carnitine. They identifiedthe SLC6A14 gene that is linked to the transport of carnitine across the blood-brain barrier and is expressed differently in females. There is no mutation in the gene, but healthy girls will express more of this activity and perhaps more transport into the brain than healthy males.

The proposed involvement of SLC6A14 could be tested in animal models by assessing the transport of carnitine across the blood brain barrier and testing for abnormalities resulting from brain carnitine deficiency, Beaudet said.

How could carnitine deficiency lead to a form of autism in an apparently healthy infant?

The researchers believe that most infants are born with adequate carnitine because carnitine is usually delivered across the placenta, and most infants are born with adequate carnitine stores, Beaudet said.

In addition, carnitine is abundant in breast milk, infant formulas and cows milk, so infants will be protected from the deficiency as long as they are exclusively fed these products.

In many cultures, when the infant is introduced to new foods between 4 and 8 months of age, the first non-milk foods are fruits, juices, cereals and vegetables, all of which contain almost no carnitine, and meats are introduced later, Beaudet said. Eggs, dairy and meats all have more substantial amounts of carnitine. Red meats are particularly rich; 1 ounce of beef contains 2,000 times more carnitine than 1 ounce of white rice. When low-carnitine solid foods are added to the diet, the intake of carnitine drops in proportion to the reduction in milk intake. This reduction in carnitine might lead to brain carnitine deficiency and autism. Many parents of children with autism spectrum disorder report picky eating and this may also reduce the amount of meat in the diet.

Beaudet and colleagues speculate that both the individuals genetic makeup and the environment might contribute to this form of autism. The researchers hypothesize that although there are dozens of genes that affect the metabolism of carnitine in the body, each gene might have a small effect, but no one gene has a severe disabling effect, such as often occurs in the more severe forms of autism. The diet is an equally important factor in this hypothesis. In addition, the researchers propose, other factors also may contribute, such as certain medications, minor illnesses (especially gastrointestinal conditions) and perhaps changes in the microbiome that might deplete carnitine from the body.

Some evidence might not support this hypothesis. Although carnitine deficiency has been reported in autism, it is not reported as frequently as this hypothesis might suggest, Beaudet said.

One way to directly test this hypothesis could be by working with families who already have one child with a milder form of autism. In these families, the risk of having another child with autism spectrum disorder is high, especially if the child is a male.

Families such as these could be enrolled in a study to determine whether supplementation with carnitine will reduce the frequency of autism in the new siblings. This would be a very direct and powerful test of the hypothesis, Beaudet said.

Beaudet indicates that the possibility that carnitine deficiency might be involved in mild forms of autism brings to the table the question of whether there should be a Recommended Daily Allowance (RDA) for carnitine in normal infant diets. In the 1980s, experts indicated that an RDA for carnitine was not necessary because the human body can make its own.

We now know that 1 in 350 males indeed cannot synthesize carnitine. The need for an RDA for carnitine perhaps should be reviewed, Beaudet said.

Beaudet also is professor of molecular and cellular biology and of pediatrics at Baylor.

The evolution of this hypothesis was supported by past grants from the Simons Foundation Autism Research Initiative, Autism Speaks #7697 and currently the National Institutes of Health Baylor College of Medicine Intellectual and Developmental Disability Research Center grant P30 HD024064.

A video describing this research and the original publication can be found online.

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Researchers study possible carnitine deficiency, autism link - Baylor College of Medicine News (press release)