Category Archives: Human Genetics

By Dennis Thompson HealthDay Reporter

TUESDAY, Feb. 25, 2014 (HealthDay News) -- U.S. Food and Drug Administration hearings opened Tuesday on a controversial fertilization technique that uses the DNA from three people -- two women and one man -- with the goal of preventing inherited genetic diseases.

The technique involves the unfertilized eggs, or "oocytes," from two females. Parts of each egg are combined to weed out inherited genetic disorders contained in one woman's DNA, and the resulting healthy egg is then fertilized using a male's sperm.

The FDA's two-day hearing is meant to provide a forum for discussing how this technique might be tested in human clinical trials.

But the discussion is expected to veer into the ethics of manipulating human genetics to produce "perfect" babies.

"The potential benefits are huge, but the potential harms are also huge," said Dr. Michelle Huckaby Lewis, a faculty member at the Johns Hopkins Berman Institute of Bioethics and the Genetics and Public Policy Center, in Washington, D.C.

The procedure could have unintended health consequences both for newborns and for future generations, as the genetic tinkering reverberates through time, Lewis said.

In addition, she said, the technique raises troubling questions of parental rights and family structure.

"When you use a technology in a new way like this, it really challenges our notions of what it means to be a parent and what it means to be a family," Lewis said.

The hearing was prompted by the work of Shoukhrat Mitalipov, an associate scientist at Oregon Health & Science University (OHSU).

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FDA Explores '3-Person' Embryo Fertilization

When it comes to developmental disorders of the brain, men and women are not created equal.

Decades of research have shown that males are at far greater risk for neurodevelopmental disorders such as autism spectrum disorder (ASD) than females. Boys, on average, are five times more likely to have autismthan girls.What causes this disparity has largely remained unknown.

Now scientists haveuncovered compelling genetic evidence to explain why the biological scales arent balanced.

According to a team of geneticists in the U.S. and Switzerland,it all boils down to whats called the female protective model. This suggests that girls have a higher tolerance for harmful genetic mutations and therefore require a larger number ofthem than boys to reach the diagnostic threshold of a developmental disorder. With identical genetic mutations, then, a boy could show symptoms of ASD while a girl could show none.

But because the female mutation threshold is higher, when girls are diagnosed with ASD, they tend to fall on the more severe end of the spectrum.

Researchers believe the same dynamic could explain why more boys are diagnosed withADHD, intellectual disabilities and schizophrenia. The findings were published Thursday in the American Journal of Human Genetics.

Geneticists analyzed DNA samples from 16,000 boys and girls with neurodevelopmental disorders.They found that, on average, females diagnosed with ASD had 1.3 to 3 times more harmful genetic alterations than males diagnosed with the disorder.

The findings suggest that as the male brain develops, smaller and more subtle genetic changes can trigger autism spectrum disorders. Female brains require a greater number or severity of mutations before showing symptoms, so their symptoms tend to be worse.

Theres no application in terms of treatment, said study author Sbastien Jacquemont of University Hospital of Lausanne in Switzerland, but it does help understand the inheritance dynamics in families.

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Genetics May Explain Why Autism Is More Common in Boys

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Males are at greater risk for neurodevelopmental disorders, such as autism spectrum disorder (ASD), than females, but the underlying reasons have been unclear. A large cohort study published by Cell Press on February 27th in the American Journal of Human Genetics provides compelling evidence in support of the "female protective model," which proposes that females require more extreme genetic mutations than do males to push them over the diagnostic threshold for neurodevelopmental disorders.

"This is the first study that convincingly demonstrates a difference at the molecular level between boys and girls referred to the clinic for a developmental disability," says study author Sbastien Jacquemont of the University Hospital of Lausanne. "The study suggests that there is a different level of robustness in brain development, and females seem to have a clear advantage."

A gender bias in the prevalence of neurodevelopmental disorders has been reported for ASD, intellectual disability, and attention deficit hyperactivity disorder. Some researchers have suggested that there is a social bias that increases the likelihood of diagnosis in males, whereas others have proposed that there are sex-based differences in genetic susceptibility. However, past studies investigating biological explanations for the gender bias have produced inconclusive results.

To examine this question, Jacquemont teamed up with Evan Eichler of the University of Washington School of Medicine to analyze DNA samples and sequencing data sets of one cohort consisting of nearly 16,000 individuals with neurodevelopmental disorders and another cohort consisting of about 800 families affected by ASD. The researchers analyzed both copy-number variants (CNVs)individual variations in the number of copies of a particular geneand single-nucleotide variants (SNVs)DNA sequence variations affecting a single nucleotide.

They found that females diagnosed with a neurodevelopmental disorder or ASD had a greater number of harmful CNVs than did males diagnosed with the same disorder. Moreover, females diagnosed with ASD had a greater number of harmful SNVs than did males with ASD. These findings suggest that the female brain requires more extreme genetic alterations than does the male brain to produce symptoms of ASD or neurodevelopmental disorders. The results also take the focus off the X chromosome for the genetic basis of the gender bias, suggesting that the burden difference is genome wide.

"Overall, females function a lot better than males with a similar mutation affecting brain development," Jacquemont says. "Our findings may lead to the development of more sensitive, gender-specific approaches for the diagnostic screening of neurodevelopmental disorders."

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Study uncovers why autism is more common in males

Story Created: Feb 26, 2014 at 12:27 AM ECT

Story Updated: Feb 26, 2014 at 12:27 AM ECT

INFECTIONS In addition to HPV infections discussed last week, there are other infections that can increase the risk of cancers. Hepatitis B and C viruses increases the risks of liver cancers. Human T-Cell Leukemia Virus -(HTLV-1)-Increases the risk of leukemia and lymphoma. Human Immunodeficiency virus (HIV)-increases the risk of lymphoma, and a rare cancer called Kaposi Sarcoma. Epstein Barr Virus (E.B. virus) is linked to increased risk of lymphoma. Human Herpes Virus is a risk factor for Kaposi Sarcoma Helicobacter Pylori-a is bacteria that causes stomach ulcers and is thought to increase the risk of stomach cancers and lymphomas.

ALCOHOL There are clear patterns that have emerged between alcohol consumption and certain types of cancer such as head and neck cancers, oesophageal, liver, breast and colon cancers. People who consume 50 or more grammes of alcohol per day have a two or three times greater risk of developing cancer than non drinkers. When alcohol is metabolised, it forms a compound known as Acetaldehyde which is toxic and a possible human carcinogen which damages human DNA. Alcohol also generates reactive oxygen species which damages the DNA, in addition, alcohol impairs the bodys ability to break down and absorb a variety of nutrients that may be associated with cancer risks. Alcohol also increases blood levels of oestrogen, a sex hormone linked to risk of breast cancers.

FOODS AND CHEMICALS Chemicals can be found in certain foods such as potato chips, French fries and other food products which are produced by high temperature cooking. One example is Asparagine which is an amino acid, a building block of proteins found in many vegetables and foods, such as potatoes. When heated to high temperatures, Asparagine, can form Acrylamide -a possible human carcinogen which can cause oral, pharynx, larynx, breast and ovarian cancers. Heterocyclic amines (HCA) and Polycyclic aromatic hydrocarbons (PAH) have also been found to be cancer causing. These are produced when muscle meat, including beef, pork or poultry, is cooked at very high temperature. HCA and PAH can cause mutations or changes in DNA that may increase cancer risks. Artificial sweeteners: These are substances that are used instead of sucrose (table sugar) to sweeten food and beverages. They include; saccharin, aspartame, sucralose, neotame and cyclamate. Many of these chemicals are thought to be carcinogenic as they have been found to cause cancers in animal studies. Agricultural products: Researches have shown that people exposed to certain products may have an increased risk of developing one or more types of cancer. Farmers, farm workers and family members may be exposed to substances such as pesticides, herbicides, engine exhausts, solvents, dusts, animal viruses, fertilisers, fuels and certain microbes that may increase cancer risks. Chemicals such as Formaldehyde, a colorless, flammable, strong smelling chemical used in building materials and house hold products,is also carcinogenic especially in cases of long term exposures. It is used in pressed woods, particle boards, plywoods, fibre boards, glues and adhesives, and is also found in fungicides, germicides, disinfectants and in preservatives in mortuaries. People who have certain jobs like painters, construction workers and those in chemical industries have increased risk of certain cancers especially when exposed to chemicals such as Asbestos, benzene, cadmium, nickel and vinyl chloride.

RADIATION Ionising radiation can cause cell damage that leads to cancers. X rays medically used for diagnostic investigations can increase cancer risk, even though the risk is low. Radiation therapy used to treat certain cancers can also increase the risk of some other cancers. Its not uncommon to meet a patient who requests an X-ray even when it is not necessary. The fact is that x-rays are a diagnostic tool, not a treatment, and they are not always beneficial. Unnecessary demand and frequent exposure to them may not be a wise idea. Ultra Violet (UV) radiation from the sun is another risk factor. Our UV index is generally high each time you see the weather news. These rays cause the early aging of the skin and skin changes that can lead to skin cancers, especially in caucasians, albinos and people with low melanin (skin pigmentations).

HAIR DYES More than 5,000 different chemicals are used in hair dye products, some of which are reported to be carcinogenic. Over the years, some studies have found an increased risk of bladder cancers in hairdressers and barbers. Some studies also linked the personal use of hair dyes with increased risks of certain cancers of the blood and bone marrow. However some of these studies need further research to make definitive conclusions but given the widespread use of hair dye products, even a small increase in risk may have a considerable public health impact.

SMOKING The role of smoking in the development of many forms of cancers is well documented. Each cigarette consists of over 400 carcinogenic materials that causes DNA damage and increased cancer risks as well as other diseases.

AGEING Cancer risk increases as you grow older, with most cancers occuring in people during their fifties or sixties. However many other cancers do develop before then, and there are some forms of cancers that afflict children.

FAMILY HISTORY Certain cancers develop because of changes or mutations in genes and risk factors can trigger some of these changes. Several cases of the same cancer types in a family are linked to inherited gene changes. If you think you are at risk, talk to your doctor and get checked. Contact Dr Maxwell on 3631807/7575411.

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U.S. medical advisers are considering whether there is scientific justification for allowing human studies of a controversial procedure known as "three-parent in vitro fertilization (IVF)," a technique supporters say could prevent horrific genetic defects but that critics believe could lead to designer babies.

During two days of public hearings starting on Tuesday, scientists were scheduled to present their research to outside advisers to the U.S. Food and Drug Administration. The agency will decide whether safety concerns raised by three-parent IVF are minimal enough to allow clinical trials to begin.

The committee is focusing only on the science, and at the end of Tuesday's hearing some committee members expressed concern that animal research cannot yet show that human studies would be safe for women and any children born via the three-parent technique.

Several panelists felt "there was probably not enough data in animals . . . to move on to human trials without answering a few additional questions" about safety, said committee chairman Dr. Evan Snyder of the Sanford/Burnham Medical Research Institute in La Jolla, California, in summarizing their views at the end of Tuesday's session.

Although the panel has not been asked to consider legal or ethical issues, members of the public focused on those. Speakers warned the panel that use of three-parent IVF "could alter the human species," represented "an unprecedented level of experimentation on non-consenting human subjects" (meaning any children born via the technique), and "could open the door to genetically modified children" who would be "manufactured products."

In the three-parent procedure, one man would donate sperm and all its DNA for in-vitro fertilization. The would-be biological mother would contribute the egg and most of its DNA. But if the mother carries harmful genetic mutations in cellular structures called mitochondria, scientists would remove her unhealthy mitochondria and substitute those of a second woman so the baby would not inherit a potentially devastating "mitochondrial disease."

Allowing such procedures "would produce genetically modified human beings," Marcy Darnovsky, executive director of the Berkeley, California-based Center for Genetics and Society, a non-profit that focuses on genetic and reproductive technologies, told the committee.

If the FDA allows clinical trials, she warned, it would introduce "a regime of high-tech consumer eugenics" and represent "the first time a government body had okayed genetic changes for humans and their descendants."

Although the FDA committee is considering only scientific issues, such as whether animal research can show mitochondrial manipulation is safe or not, the agency said it is prepared to go beyond that.

"We have heard the concerns expressed at the advisory committee meeting, and will take the information back to consider whether we need to facilitate a public discussion and, if so, how best to do this," spokeswoman Jen Rodriguez told Reuters.

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FDA weighs evidence on producing '3-parent' embryos

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In last week's column, a reader asked whether she should be tested for genes linked to Alzheimer's disease. Today, I thought I'd give you my view on the larger question: Will studies of our genes change the practice of medicine and improve our lives?

My answer: During my career, progress in human genetics has been greater than virtually anyone imagined. However, human genetics also has turned out to be much more complicated than people imagined. As a result, we have not moved as rapidly as we had hoped in changing medical practice.

I graduated from medical school in the late 1960s. We knew what human genes were made of -- DNA -- and we were beginning to understand how genes work. We had even identified a handful of genes that were linked to specific diseases. We assumed that disease resulted from an abnormality in the structure of a gene.

If I had asked any biologist on the day I graduated, Will we ever know how many genes we have, and the exact structure of each gene? I'll bet the answer would have been: Not in my lifetime, or my children's lifetime.

They would have been wrong. Today we do know those answers. Indeed, some diseases are caused by an abnormality in the structure of genes. In fact, sometimes it is very simple: one particular change at one particular spot in just one particular gene leads to a specific disease. Sickle cell anemia is an example.

Unfortunately, with most diseases it's far from that simple. The first complexity: Most diseases are influenced by the structure of multiple genes, not just one. Examples are diabetes and high blood pressure.

The second complexity: Many diseases are explained not by an abnormal gene structure, but by whether genes are properly turned on or off. Most cancers fall into this category.

What do I mean by that? Every cell in our body has the same set of genes. Yet, a cell in our eye that sees light is different from a cell in our stomach that makes acid. Why? Because different genes are turned on in each type of cell.

Similarly, if a gene with a normal structure is not properly turned on or off, a cell can malfunction -- it can become diseased. Whether a gene is turned on properly is proving to be a more important cause of disease than we once imagined.

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ASK DOCTOR K: Progress in genetics will lead to better diagnosis

Details Published on Tuesday, 25 February 2014 16:53

Hardened plaque discovered on the teeth of 1,000 year old human skeletons has revealed not only their diets but the diseases they faced.HARDENED plaque discovered on the teeth of 1,000-year-old human skeletons has revealed the world's oldest case of gum disease.

Described as a 'microbial Pompeii', the plaque preserved bacteria and microscopic particles of food on the surfaces of teeth, effectively creating a mineral tomb for microbiomes.

And it revealed that our ancestors had gum disease that was caused by the same bacteria that plagues modern man, despite major changes in diet and hygiene.

They found that the ancient human oral microbiome already contained the basic genetic machinery for antibiotic resistance over eight centuries before the invention of antibiotics in the 1940s.

DNA testing of the tartar also showed some of the things ancient humans had been eating, such a vegetables, which do not show up in fossil records.

Gum disease is caused by a build-up of plaque on the teeth and is thought to affect over half of adults in the UK.

The teeth were taken from skeletons found at a site in Dalheim, Germany.Plaque is a sticky substance that contains bacteria and when it hardens it forms tartar.

Unlike bone, which rapidly loses much of its molecular information when buried, calculus grows slowly in the mouth and enters the soil in a much more stable state, helping it to preserve biomolecules.

Researchers from the University of York, along with Swiss and Danish colleagues, said studying plaque will be more important than teeth in discovering the lifestyles of our past ancestors.

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Plaque On 1000-Year-Old Human Teeth Could Unlock Secrets Of Medieval Diet And Disease

GREENWOOD A new partnership will establish formal collaboration among genetic researchers and Clemson University faculty at the Greenwood Genetic Center and Self Regional Healthcare, expanding an already successful working relationship.

Self Regional Healthcare will support the Clemson University Center for Human Genetics with a gift of $5.6 million over three years. The gift consists of an initial contribution of $2 million for the centers facilities and a subsequent contribution of $3.6 million to support research in genetics and human diagnostics at the facility located on the Greenwood Genetic Center campus.

Todays announcement will create a new pipeline for genetic research, said John Pillman, chairman of the Self Regional board of trustees, on Friday. The collaboration of these three partners will ultimately connect genetic therapeutics research to patients.

Jim Pfeiffer, president and chief executive officer of Self Regional, said the partnership will accelerate the rate of innovation in genetic medicine. This is what I like to call a win-win-win scenario, said Pfeiffer.

Steve Skinner, director of the Greenwood Genetic Center, said such collaborations are crucial to turning research advances into clinically available therapies for patients, not only in Greenwood and across South Carolina, but globally.

This collaboration is a major step forward for patients as we combine the resources and strengths of each institution: Selfs commitment to patient care, Clemsons expertise in basic scientific research and our experience with genetic disorders and treatment, Skinner said.

Self Regional and the Genetic Center have had an affiliation agreement since 1975 with the Genetic Centers clinical faculty serving as the Department of Medical Genetics for Self Regional.

Clemson University President James P. Clements said the announcement brings us a step closer to moving basic discoveries in human genetics from a research environment to a clinical setting where they can be used to diagnose and treat genetic-related human disorders.

Clemson is proud to be part of this important collaborative effort, and were grateful to Self Regional Healthcare for its support of our research efforts at the Greenwood Genetic Center, Clements said.

Clemsons Steve Kresovich, the Robert and Lois Coker Trustees Chair of Genetics, is responsible for overseeing research programs and managing collaborative activities between Clemson faculty and personnel at the partner institutions.

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Self Regional Healthcare, Clemson, Genetic Center create national genetics research hub

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Newswise Philadelphia, Feb. 20, 2014 A large international study analyzing genes in tens of thousands of individuals has discovered 11 new genetic signals associated with blood pressure levels. Ten of those signals are in or very near genes encoding proteins that appear to be likely targets for drugs already in existence or in development.

The fact that most of these new gene signals are druggable targets offers the possibility of expedited pharmaceutical development of therapeutics for high blood pressure, a serious risk factor for cardiovascular diseases, said geneticist Brendan J. Keating, D. Phil., of The Center for Applied Genomics at The Childrens Hospital of Philadelphia, co-senior author of the study. Some of the protein targets already are targets of existing drugs for other diseases, while others are the focus of drugs currently in early-phase clinical trials or under preclinical development.

Keating collaborated with two other senior co-authors, Folkert W. Asselbergs, M.D., Ph.D., of University Medical Center Utrecht, the Netherlands, and Patricia B. Munroe, Ph.D., of Queen Mary University, London, U.K. The study appears online today in the American Journal of Human Genetics. Study co-authors were from the U.S., the U.K., the Netherlands, Canada, Germany, Sweden and Ireland.

High blood pressure, or hypertension, a chronic medical condition, is a well-known risk factor for heart disease, stroke, peripheral artery disease and chronic kidney disease. It is a complex condition, affected by many different genes. Because not all patients respond well to current blood pressure medications and other treatments, and other patients require combinations of three or more drugs, there is a substantial unmet need for improved medicines.

In the current study, the researchers performed a discovery analysis of DNA from more than 87,000 individuals of European ancestry. They then assessed their initial findings in a replication test, using an independent set of another 68,000 individuals.

The study team confirmed 27 previously discovered gene signals associated with blood pressure, and discovered 11 novel genetic signals. When the researchers used pharmacological databases to analyze potential targets in the discovered genetic regions, they found that gene products associated with 10 of the genes were predicted to be targets for small-molecule drugs. Two genes, KCNJ11 and NQO1, in fact, are already currently targeted by existing approved drugs. If clinicians can reposition existing drugs to treat some patients with hypertension, this will save significant time in drug development, as they wont be starting development from scratch, said Keating.

Keating added that other gene signals discovered in the study are associated with candidate drugs currently under development within pharmaceutical companies, and it may be possible that they can be repositioned as blood pressure therapeutics.

He stressed that even with possible repositioning, much research remains to be done to determine which drug candidates are effective against hypertension, possibly in personalized treatments based on patients genetic makeup. Keating added that the list of genes affecting blood pressure will likely grow as research continues.

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CHOP Researcher Co-Leads Study Finding Genes that Affect Blood Pressure