Posted on 07/31/2008 10:02:31 AM PDT by neverdem
Two large studies of schizophrenia patients have yielded the most convincing evidence yet that the disease can be caused by mistakes in genes. The researchers linked a much higher risk for schizophrenia to three chromosomal regions that are missing chunks of DNA. Although only a tiny fraction of patients carried these particular glitches, similar errors may help explain other cases of the disease.
Schizophrenia is a severe mental disorder involving hallucinations and delusions that affects as many as 1 in 100 people; it often runs in families. So far, searches for common genes linked to schizophrenia have been unsuccessful. In March, however, researchers reported a new clue in Science: Schizophrenics are more likely than healthy people to have rare variations in gene copy number--that is, they have fewer or more copies of a gene than most other people. Many of these copy number changes occurred in only one individual or one family, however, and the study could not pin down the risks associated with a particular variant.
Now the largest studies to date have bolstered the case for copy number variants. The U.S.–European International Schizophrenia Consortium, which compared copy numbers in about 3400 patients and 3200 controls, found that large chunks of extra or missing DNA were 15% more common in people with the disease compared with controls. Moreover, the researchers found a much greater risk for patients with DNA deletions in two specific locations on chromosome 1 and chromosome 15. A second study by deCODE Genetics in Reykjavik, Iceland, and a European consortium known as SGENE, which involved about 4700 schizophrenia cases and 41,200 controls, pinpointed these same two variants and an additional one on chromosome 15. Both papers are published online today in Nature.
One of the variants increased the risk at least threefold, and the other two boosted it more than 10-fold, the teams reported. These are "very large risks," said deCODE CEO Kári Stefánsson at a telephone press conference yesterday. Both studies also confirmed a previously reported deletion on chromosome 22 that is associated with a disease called velocardiofacial syndrome that often leads to schizophrenia.
Although each of the copy number variants is carried by less than 1% of the population, these and other copy number variants may be part of common biochemical pathways involved in brain development, Stefánsson and others say. "They give a great deal of hope ... that we're moving towards understanding the causes of the disease," Pamela Sklar of Massachusetts General Hospital in Boston said during the press conference. Sklar, a psychiatrist and geneticist, coordinated the International Schizophrenia Consortium. Some of the same regions have been linked to autism and mental retardation, pointing to a possible common mechanism.
Psychiatrist Jon McClellan of the University of Washington, Seattle, corresponding author of the Science paper earlier this year, explains that the copy number changes tend to occur in known DNA "hot spots" where mistakes are sometimes made when chromosomes get copied during egg and sperm formation. "If any one gets disrupted, that could lead to illness," he says. But disentangling these pathways in the brain--the most complicated organ--won't be easy, he says.
A third paper, appearing today in Nature Genetics from a team led by Michael O'Donovan at the University of Cardiff in the United Kingdom, reports a mutation that may raise the risk of schizophrenia in the general population. The study, which scanned the entire genome for common markers associated with disease, pointed to a gene involved in gene expression. However, people with this variant had only a 12% higher risk of developing schizophrenia, which suggests it plays a minor role, McClellan notes. And as with other genome-wide association studies, he adds, the finding needs to be replicated by other researchers.
Rare Mutations Hint at Multiple Schizophrenias
ScienceNOW 2008 (327), 1.
Gene Bolsters Genetic Basis of Schizophrenia
ScienceNOW 2005 (1121), 1.
New Schizophrenia Gene Identified
ScienceNOW 2005 (329), 2.
“I only know two schizophrenics, and you are both of them”
Yes, I am.
No, you're not.
So, assuming for a minute that homosexuals are correct in claiming that being gay is genetic, does this study indicate that genetic deformity is a disorder/illness or normal?
Multiple personality disorder is not schizophrenia. Neither diagnosis is remotely funny.
Neither are Alzheimer's or AIDS but I know some great jokes about both.
Much humor is rooted in adversity, if you cant laugh at it without being offended you are probably a Democrat..
Guess that puts paid to the pharma industry’s claim that schizophrenia is caused by a “chemical imbalance”.
I wouldn't presume to answer that. IIRC, this first link describes these mutations in schizophrenia as being spontaneous events, i.e. de novo.
Gene-Hunters Find Hope and Hurdles in Schizophrenia Studies
Gene surveys identify schizophrenia triggers
FReepmail me if you want on or off my health and science ping list.
The genetic problems cause the chemical imbalance.
I know lots of funny jokes too....I think this poster tried to put something interesting out there about a topic that is pretty serious, not expecting humor. It's not unusual to get a surprised or even offended reaction. Hardly makes the poster a democrat.
If you had ever seen the horror show that such brain diseases can be you would not find it a joking matter..... I hope that you and your family and friends are spared such agonies, and that you will learn that joking about this is about as “funny” as joking about quadraplegics.
Not necessarily - so much is still unknown, but it seems at least plausible that such genetic variations could affect the brain's output, absorption, and/or "balance" of certain neurotransmitters. The chemistry is not the most fundamental causal level, of course, but it could be that certain pathways will be found which can be favorably affected by new medicines. Some brain diseases may turn out to primarily "hard-wired" in the cell structures, but others may also be at least in part driven by the levels of various neurotransmitters (which of course are produced by or re-absorbed by various types of cells).
It is at least possible that new medications will have better results for treatments, as has been the case with at least some types of depression and manic-depression.
There’s a huge (gigantic, enormous) difference between patients and their families/friends joking about something for relief, and unaffected strangers laughing AT them. The latter is cruel and is irrelevant to political outlook or beliefs, I would hope.
As a cancer patient I made plenty of jokes about what I was going through, it was indeed a good way of coping with a horrendous period of illness and severe chemo, surgeries, etc. But I certainly never joked (uninvited) about what any other patient went through..... and I would not look favorably at a total stranger who thought it was appropriate to laugh AT the agonies I was going through. You don’t have to be a Democrat to disdain someone who takes pleasure in the suffering of others (except when we are all joking about terrorists getting offed, which is certainly most appropriate!!!!!).
Thanks for pointing that out, it's annoying how pervasive that misconception still is. Is it just because of that stupid made-for-TV movie from what, the seventies?
That one's a keeper, I never knew that. Thanks for the link.
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