Two teams of European scientists say they have discovered new genetic variants associated with Alzheimer’s disease. The variants account for about 20 percent of the genetic risk of the disease, and may lead to a better understanding of its biology, the scientists say.
One of the teams, led by Julie Williams of Cardiff University in Wales, scanned the genomes of about 19,000 patients, the largest study so far conducted on Alzheimer’s, and turned up two variants that have a statistically significant association with the disease. A second study, led by Philippe Amouyel of the University of Lille in France, also found two variants, one of which is the same as detected by the Cardiff team.
The fact that two studies could agree on at least one gene is an advance. More than 550 genes have been proposed in various small-scale studies as the cause of Alzheimer’s, but all have failed the test of replication by others, Dr. Amouyel said.
READ MORE @ NY TIMES
Showing posts with label genes. Show all posts
Showing posts with label genes. Show all posts
Monday, September 7, 2009
Sunday, July 12, 2009
Childhood-onset schizophrenia remains a mystery
A study at the National Institute of Mental Health that has already spanned 18 years may yield crucial answers to the rare disorder.
So rare is the child form of schizophrenia, it has taken researchers at the National Institute of Mental Health 18 years to diagnosis and collect data on 110 children.
"We are trying to understand schizophrenia in a comprehensive way," says Dr. Nitin Gogtay, a researcher involved with the project in Bethesda, Md. "We see the illness in a very pure form. At that age, there are no confounding factors, like alcohol or drug abuse. We feel a lot of answers will come out of this study."
The study, the largest of its kind worldwide, has already yielded clues about the disease -- the most severe mental illness. Although schizophrenia afflicts about 1% of adults, it occurs in about one of every 30,000 to 50,000 children 13 and under. The causes of the disease are a mystery, although genes are known to play a role. In young children, a brain injury at or near the time of birth may contribute to its onset.
READ MORE @ LOS ANGELES TIMES
So rare is the child form of schizophrenia, it has taken researchers at the National Institute of Mental Health 18 years to diagnosis and collect data on 110 children.
"We are trying to understand schizophrenia in a comprehensive way," says Dr. Nitin Gogtay, a researcher involved with the project in Bethesda, Md. "We see the illness in a very pure form. At that age, there are no confounding factors, like alcohol or drug abuse. We feel a lot of answers will come out of this study."
The study, the largest of its kind worldwide, has already yielded clues about the disease -- the most severe mental illness. Although schizophrenia afflicts about 1% of adults, it occurs in about one of every 30,000 to 50,000 children 13 and under. The causes of the disease are a mystery, although genes are known to play a role. In young children, a brain injury at or near the time of birth may contribute to its onset.
READ MORE @ LOS ANGELES TIMES
Tuesday, June 16, 2009
Report on Gene for Depression Is Now Faulted
One of the most celebrated findings in modern psychiatry — that a single gene helps determine one’s risk of depression in response to a divorce, a lost job or another serious reversal — has not held up to scientific scrutiny, researchers reported Tuesday.
The original finding, published in 2003, created a sensation among scientists and the public because it offered the first specific, plausible explanation of why some people bounce back after a stressful life event while others plunge into lasting despair.
The new report, by several of the most prominent researchers in the field, does not imply that interactions between genes and life experience are trivial; they are almost certainly fundamental, experts agree.
But it does suggest that nailing down those factors in a precise way is far more difficult than scientists believed even a few years ago, and that the original finding could have been due to chance. The new report is likely to inflame a debate over the direction of the field itself, which has found that the genetics of illnesses like schizophrenia and bipolar disorder remain elusive.
READ MORE @ NY TIMES
The original finding, published in 2003, created a sensation among scientists and the public because it offered the first specific, plausible explanation of why some people bounce back after a stressful life event while others plunge into lasting despair.
The new report, by several of the most prominent researchers in the field, does not imply that interactions between genes and life experience are trivial; they are almost certainly fundamental, experts agree.
But it does suggest that nailing down those factors in a precise way is far more difficult than scientists believed even a few years ago, and that the original finding could have been due to chance. The new report is likely to inflame a debate over the direction of the field itself, which has found that the genetics of illnesses like schizophrenia and bipolar disorder remain elusive.
READ MORE @ NY TIMES
Monday, January 12, 2009
Women-only gene link to dementia
Scientists have found a genetic risk factor for late onset Alzheimer's disease which is only carried by women.
The discovery is the first evidence to suggest that genetics may partly explain why more women than men tend to develop the disease.
The key variant was found in a gene on the X chromosome, of which females have two copies, but males only one.
The study, by the Mayo Clinic College of Medicine, features in the journal Nature Genetics.
The Mayo team carried out a detailed genetic analysis of patients with Alzheimer's diease.
They identified a particular variant of a gene called PCDH11X which appeared to be closely linked to a higher risk of the disease.
However, further analysis showed that the association was almost entirely restricted to women.
READ MORE @ BBC
The discovery is the first evidence to suggest that genetics may partly explain why more women than men tend to develop the disease.
The key variant was found in a gene on the X chromosome, of which females have two copies, but males only one.
The study, by the Mayo Clinic College of Medicine, features in the journal Nature Genetics.
The Mayo team carried out a detailed genetic analysis of patients with Alzheimer's diease.
They identified a particular variant of a gene called PCDH11X which appeared to be closely linked to a higher risk of the disease.
However, further analysis showed that the association was almost entirely restricted to women.
READ MORE @ BBC
Friday, August 1, 2008
Schizophrenia Ties to Random DNA Mutations Bolstered in Study
Spontaneous defects in DNA may trigger schizophrenia, according to research that bolsters results of smaller studies aimed at finding the genetic causes of the disabling mental disorder.
In the largest study of its kind, international research teams found evidence that schizophrenia can be caused when genes are duplicated or deleted in an often random process that isn't inherited from parents, according to reports published today in the journals Nature and Nature Genetics. Scientists found that people with schizophrenia are more than 10 times as likely to have these rare chromosomal alterations as people who don't have the illness.
While the findings fill in parts of the puzzle of the disease, they also suggest it may be caused by a complex set of genetic flaws, which could complicate the search for effective treatments.
READ MORE @ BLOOMBERG
In the largest study of its kind, international research teams found evidence that schizophrenia can be caused when genes are duplicated or deleted in an often random process that isn't inherited from parents, according to reports published today in the journals Nature and Nature Genetics. Scientists found that people with schizophrenia are more than 10 times as likely to have these rare chromosomal alterations as people who don't have the illness.
While the findings fill in parts of the puzzle of the disease, they also suggest it may be caused by a complex set of genetic flaws, which could complicate the search for effective treatments.
READ MORE @ BLOOMBERG
Thursday, July 31, 2008
Gene-Hunters Find Hope and Hurdles in Schizophrenia Studies
Two groups of researchers hunting for schizophrenia genes on a larger scale than ever before have found new genetic variants that point toward a different understanding of the disease.
The variants discovered by the two groups, one led by Dr. Kari Stefansson of Decode Genetics in Iceland and the other by Dr. Pamela Sklar of Massachusetts General Hospital, are rare. They substantially increase the risk of schizophrenia but account for a tiny fraction of the total number of cases.
This finding, coupled with the general lack of success so far in finding common variants for schizophrenia, raises the possibility that the genetic component of the disease is due to a large number of variants, each of which is very rare, rather than to a handful of common variants.
“What is beginning to emerge is that a lot of the risk of brain diseases is conferred by rare deletions,” Dr. Stefansson said. The three variants discovered by his group and Dr. Sklar’s involve the deletion of large sections of DNA from specific sites in a patient’s genome.
READ MORE @ NY TIMES
The variants discovered by the two groups, one led by Dr. Kari Stefansson of Decode Genetics in Iceland and the other by Dr. Pamela Sklar of Massachusetts General Hospital, are rare. They substantially increase the risk of schizophrenia but account for a tiny fraction of the total number of cases.
This finding, coupled with the general lack of success so far in finding common variants for schizophrenia, raises the possibility that the genetic component of the disease is due to a large number of variants, each of which is very rare, rather than to a handful of common variants.
“What is beginning to emerge is that a lot of the risk of brain diseases is conferred by rare deletions,” Dr. Stefansson said. The three variants discovered by his group and Dr. Sklar’s involve the deletion of large sections of DNA from specific sites in a patient’s genome.
READ MORE @ NY TIMES
Sunday, June 29, 2008
ADHD Gene Doesn't Predict Response to Drugs
Canadian researchers report that their discovery of a gene variant that seems to affect the severity of attention-deficit hyperactivity disorder did not help them predict which patients are likely to respond to a class of drugs widely used to treat the disorder.
The lack of a connection between the variant and response to methylphenidates was a blow for researchers, who have hoped to use genetic data to better predict who might be the best candidates for this treatment. Ritalin is one example of a methylphenidate.
"It is a negative study," said Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at Schneider Children's Hospital in New Hyde Park, N.Y. "The goal is to try and better identify patients who are best going to respond to which medicine, and they didn't get the findings they were hoping to find. Their theory wasn't supported by the data."
READ MORE @ FORBES
The lack of a connection between the variant and response to methylphenidates was a blow for researchers, who have hoped to use genetic data to better predict who might be the best candidates for this treatment. Ritalin is one example of a methylphenidate.
"It is a negative study," said Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at Schneider Children's Hospital in New Hyde Park, N.Y. "The goal is to try and better identify patients who are best going to respond to which medicine, and they didn't get the findings they were hoping to find. Their theory wasn't supported by the data."
READ MORE @ FORBES
Sunday, June 15, 2008
Mutation Related To ADHD Drug Metabolism Discovered
Researchers within the Darby Children’s Research Institute at the Medical University of South Carolina (MUSC) have discovered a gene mutation directly involved in the metabolism of the most common and perhaps most known medication used to treat ADHD, methylphenidate (MPH), or Ritalin. The discovery may open the door to pre-testing of patients for the appropriate ADHD medication, instead of having to undergo trial and error.
It’s not unusual for scientists to focus their work in one direction, only to discover something unexpected. Researchers within the Darby Children’s Research Institute at the Medical University of South Carolina (MUSC) have discovered a gene mutation directly involved in the metabolism of the most common and perhaps most known medication used to treat ADHD, methylphenidate (MPH), or Ritalin®. This research is described in full detail in the June 2008 issue of the American Journal of Human Genetics.
READ MORE @ SCIENCE DAILY
It’s not unusual for scientists to focus their work in one direction, only to discover something unexpected. Researchers within the Darby Children’s Research Institute at the Medical University of South Carolina (MUSC) have discovered a gene mutation directly involved in the metabolism of the most common and perhaps most known medication used to treat ADHD, methylphenidate (MPH), or Ritalin®. This research is described in full detail in the June 2008 issue of the American Journal of Human Genetics.
READ MORE @ SCIENCE DAILY
Saturday, December 22, 2007
Not Yet: CDC panel questions antidepressant gene test
About half of all depressed people who take standard antidepressant drugs fail to improve. Some suffer unpleasant side effects and abandon the medicines, while others simply don't feel better. Commercial tests claim to predict, by a genetic analysis, how well individual patients will fare on different antidepressants, but a panel convened by the Centers for Disease Control and Prevention (CDC) in Atlanta now says that the tests don't work as advertised.
The panel "discourages" use of such tests until further studies clarify their value, according to a statement the group published in the December Genetics in Medicine.
"That isn't to say that eventually there won't be a role for these tests. We just don't know what that role is yet," says panel member Joan Scott of the Genetics and Public Policy Center in Washington, D.C.
The tests scan a person's DNA for variations in genes for two key liver enzymes. These enzymes break down selective serotonin reuptake inhibitors (SSRIs), a standard class of antidepressants that includes fluoxetine (Prozac) and nearly a dozen other drugs. Variations in the two enzymes affect how quickly different people clear SSRIs from their blood, which in turn influences the drugs' effectiveness.
READ MORE @ SCIENCE NEWS
The panel "discourages" use of such tests until further studies clarify their value, according to a statement the group published in the December Genetics in Medicine.
"That isn't to say that eventually there won't be a role for these tests. We just don't know what that role is yet," says panel member Joan Scott of the Genetics and Public Policy Center in Washington, D.C.
The tests scan a person's DNA for variations in genes for two key liver enzymes. These enzymes break down selective serotonin reuptake inhibitors (SSRIs), a standard class of antidepressants that includes fluoxetine (Prozac) and nearly a dozen other drugs. Variations in the two enzymes affect how quickly different people clear SSRIs from their blood, which in turn influences the drugs' effectiveness.
READ MORE @ SCIENCE NEWS
Wednesday, December 5, 2007
Newly-identified Exercise Gene Could Help With Depression
Boosting an exercise-related gene in the brain works as a powerful anti-depressant in mice--a finding that could lead to a new anti-depressant drug target, according to a Yale School of Medicine report in Nature Medicine.
"The VGF exercise-related gene and target for drug development could be even better than chemical antidepressants because it is already present in the brain," said Ronald Duman, professor of psychiatry and senior author of the study.
Depression affects 16 percent of the population in the United States, at a related cost of $83 billion each year. Currently available anti-depressants help 65 percent of patients and require weeks to months before the patients experience relief.
Duman said it is known that exercise improves brain function and mental health, and provides protective benefits in the event of a brain injury or disease, but how this all happens in the brain is not well understood. He said the fact that existing medications take so long to work indicates that some neuronal adaptation or plasticity is needed.
READ MORE @ SCIENCE DAILY
"The VGF exercise-related gene and target for drug development could be even better than chemical antidepressants because it is already present in the brain," said Ronald Duman, professor of psychiatry and senior author of the study.
Depression affects 16 percent of the population in the United States, at a related cost of $83 billion each year. Currently available anti-depressants help 65 percent of patients and require weeks to months before the patients experience relief.
Duman said it is known that exercise improves brain function and mental health, and provides protective benefits in the event of a brain injury or disease, but how this all happens in the brain is not well understood. He said the fact that existing medications take so long to work indicates that some neuronal adaptation or plasticity is needed.
READ MORE @ SCIENCE DAILY
Sunday, December 2, 2007
One Gene Variant Puts Stressed Women At Risk For Depression; Has Opposite Effect In Men
A common variation in genes puts women who are under chronic stress at risk for increased depressive symptoms, but has the exact opposite effect in men, according to new findings from Duke University Medical Center researchers.
The researchers analyzed two independent samples of healthy individuals for the presence of a genetic variant that regulates levels of serotonin — a neurotransmitter that is linked to health in numerous ways, including emotion regulation.
One version of the gene puts women who are under chronic stress at risk for more severe depressive symptoms. But among men, the same gene variant appeared to be protective against depression. In fact, men with the opposite gene variant were the ones who experienced more depressive symptoms when under chronic stress.
READ MORE @ SCIENCE DAILY
The researchers analyzed two independent samples of healthy individuals for the presence of a genetic variant that regulates levels of serotonin — a neurotransmitter that is linked to health in numerous ways, including emotion regulation.
One version of the gene puts women who are under chronic stress at risk for more severe depressive symptoms. But among men, the same gene variant appeared to be protective against depression. In fact, men with the opposite gene variant were the ones who experienced more depressive symptoms when under chronic stress.
READ MORE @ SCIENCE DAILY
Saturday, October 20, 2007
How Schizophrenia Develops: Major Clues Discovered
Schizophrenia may occur, in part, because of a problem in an intermittent on/off switch for a gene involved in making a key chemical messenger in the brain, scientists have found in a study of human brain tissue. The researchers found that the gene is turned on at increasingly high rates during normal development of the prefrontal cortex, the part of the brain involved in higher functions like thinking and decision-making -- but that this normal increase may not occur in people with schizophrenia.
The gene, GAD1, makes an enzyme essential for production of the chemical messenger, called GABA. The more the gene is turned on, the more GABA synthesis can occur, under normal circumstances. GABA helps regulate the flow of electrical traffic that enables brain cells to communicate with each other. It is among the major neurotransmitters in the brain.
Abnormalities in brain development and in GABA synthesis are known to play a role in schizophrenia, but the underlying molecular mechanisms are unknown. In this study, scientists discovered that defects in specific epigenetic actions -- biochemical reactions that regulate gene activity, such as turning genes on and off so that they can make substances like the GAD1 enzyme -- are involved.
READ MORE @ SCIENCE DAILY
The gene, GAD1, makes an enzyme essential for production of the chemical messenger, called GABA. The more the gene is turned on, the more GABA synthesis can occur, under normal circumstances. GABA helps regulate the flow of electrical traffic that enables brain cells to communicate with each other. It is among the major neurotransmitters in the brain.
Abnormalities in brain development and in GABA synthesis are known to play a role in schizophrenia, but the underlying molecular mechanisms are unknown. In this study, scientists discovered that defects in specific epigenetic actions -- biochemical reactions that regulate gene activity, such as turning genes on and off so that they can make substances like the GAD1 enzyme -- are involved.
READ MORE @ SCIENCE DAILY
Saturday, September 29, 2007
Genes Tied to Bad Reactions to Antidepressant Drug
Variations in two genes may increase the likelihood that a person will report suicidal thoughts after taking an antidepressant, researchers reported yesterday. The finding could help doctors develop tests to predict which patients will do well on such medications and which will react badly.
The authors of the study, which was released to reporters yesterday and will appear in The American Journal of Psychiatry on Monday, said that the findings were preliminary and would need to be verified by further testing.
The study focused on reactions to only one drug, Celexa from Forest Laboratories, and found no link between the gene variations and dangerous behavior like suicide attempts.
READ MORE @ NY TIMES
The authors of the study, which was released to reporters yesterday and will appear in The American Journal of Psychiatry on Monday, said that the findings were preliminary and would need to be verified by further testing.
The study focused on reactions to only one drug, Celexa from Forest Laboratories, and found no link between the gene variations and dangerous behavior like suicide attempts.
READ MORE @ NY TIMES
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