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Date Posted: 22:52:18 11/09/04 Tue
Author: Lijdrec
Author Host/IP: ca-02.cinergycom.net / 216.135.2.29
Subject: Re: Final Draft
In reply to:
Lijdrec
's message, "Final Draft" on 21:58:15 08/24/04 Tue
Mothers' genetic skew linked to gay sons
10:26 09 November 04
There has been much debate over “gay genes”. Now an intriguing study raises another possibility: in some cases, variations in the genetic program we inherit from our parents, rather than in the genes themselves, might determine sexual preference.
Our genome is “programmed” by the addition of chemical markers called methyl groups to the DNA, which shut down genes. One of the most dramatic examples of methylation is the shutdown of one of the two X chromosomes (one from each parent) in every woman’s cells, a process called X-inactivation (New Scientist print edition, 10 May 2003).
Normally, this process is random; either of the X chromosomes can be inactivated.
But when Sven Bocklandt of the University of California, Los Angeles, compared blood and saliva samples from 97 mothers of gay men with samples from 103 mothers without gay children he found this process was extremely skewed in the mothers with gay sons, with one X chromosome being far more likely to be inactivated than the other.
"I like males"
Only 4% of the mothers without gay sons showed this skewing, compared with 14% of mothers with at least one gay son. Among mothers with two or more gay sons, the figure was 23%.
Such skewing is generally associated with genetic disorders, but the mothers all appear to be healthy. Their daughters also seemed unaffected, with only 1 out of 24 showing skewing.
Bocklandt suspects that whatever is causing the skewed methylation of the X chromosome also affects the methylation of certain genes on the chromosomes the women pass on to their sons. Mothers might not be resetting their own “I like males” program, he told a meeting of the American Society of Human Genetics in Toronto last week.
“I’m not absolutely persuaded, but it’s an interesting hypothesis,” says Ian Craig of the Institute of Psychiatry in London. “Until you’ve got some molecular way to test it, it’s just a nice idea.”
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Oh boy.... now the "god gene" -- Lijdrec, 00:35:27 11/14/04 Sun (ca-02.cinergycom.net/216.135.2.29)
'God gene' discovered by scientist behind gay DNA theory
By Elizabeth Day -- telegraph.co.uk - (Filed: 14/11/2004)
Religious belief is determined by a person's genetic make-up according to a study by a leading scientist.
After comparing more than 2,000 DNA samples, an American molecular geneticist has concluded that a person's capacity to believe in God is linked to brain chemicals.
His findings were criticised last night by leading clerics, who challenge the existence of a "god gene" and say that the research undermines a fundamental tenet of faith - that spiritual enlightenment is achieved through divine transformation rather than the brain's electrical impulses.
Dr Dean Hamer, the director of the Gene Structure and Regulation Unit at the National Cancer Institute in America, asked volunteers 226 questions in order to determine how spiritually connected they felt to the universe. The higher their score, the greater a person's ability to believe in a greater spiritual force and, Dr Hamer found, the more likely they were to share the gene, VMAT2.
Studies on twins showed that those with this gene, a vesicular monoamine transporter that regulates the flow of mood-altering chemicals in the brain, were more likely to develop a spiritual belief.
Growing up in a religious environment was said to have little effect on belief. Dr Hamer, who in 1993 claimed to have identified a DNA sequence linked to male homosexuality, said the existence of the "god gene" explained why some people had more aptitude for spirituality than others.
"Buddha, Mohammed and Jesus all shared a series of mystical experiences or alterations in consciousness and thus probably carried the gene," he said. "This means that the tendency to be spiritual is part of genetic make-up. This is not a thing that is strictly handed down from parents to children. It could skip a generation - it's like intelligence."
His findings, published in a book, The God Gene: How Faith Is Hard-Wired Into Our Genes, were greeted sceptically by many in the religious establishment.
The Rev Dr John Polkinghorne, a fellow of the Royal Society and a Canon Theologian at Liverpool Cathedral, said: "The idea of a god gene goes against all my personal theological convictions. You can't cut faith down to the lowest common denominator of genetic survival. It shows the poverty of reductionist thinking."
The Rev Dr Walter Houston, the chaplain of Mansfield College, Oxford, and a fellow in theology, said: "Religious belief is not just related to a person's constitution; it's related to society, tradition, character - everything's involved. Having a gene that could do all that seems pretty unlikely to me."
Dr Hamer insisted, however, that his research was not antithetical to a belief in God. He pointed out: "Religious believers can point to the existence of god genes as one more sign of the creator's ingenuity - a clever way to help humans acknowledge and embrace a divine presence."
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Re: Final Draft -- Lij, 17:03:23 01/23/05 Sun (ca-01.cinergycom.net/216.135.2.28)
And another.....
Gene Scan Suggests Homosexuality Origin
David Ryan Alexander, PlanetOut Network
Friday, January 21, 2005 / 04:27 PM
A new genetic study released Jan. 12 claims to "help explain why some men are gay and other men are heterosexual." The study, published in the biomedical journal Human Genetics, analyzed 456 individuals from 146 unrelated families with two or more gay brothers and claims to be the first full genome scan of sexual orientation in men.
"We found three chromosomal regions that are likely to have genes within them that influence sexual orientation," said Brian Mustanski of the University of Illinois, one of the six scientists from a number of institutions who conducted the study.
"I think we essentially found these regions that are likely to influence sexual orientation," Mustanski said. "We found some genes that influence hormones and brain development. The next step is to look at specific genes in a new family sample to see if those are the exact genes that affect sexual orientation."
The study also stated that "given the complexity of sexual orientation, numerous genes are likely to be involved, many of which are expected to be autosomal (or of a non-sex chromosome) than sex-linked." In previous studies regarding gay male twins, the report said, only limited connection could be made showing male sexual orientation as being inherited from the X-chromosome, or sex chromosome.
"Previous research had looked exclusively at the X-chromosome," Mustanski said, "and found that the region right at the tip of the X-chromosome may influence sexual orientation."
The current study sought to provide a scan analyzing both sex and non-sex chromosomes to identify all genes that potentially contribute to variation in sexual orientation.
Mustanski compared the study to finding one person in a town of 40,000 people. "You make some assumptions about where they might be, knocking on one door on every street," he said. "You're going to narrow it down considerably."
According to Mustanski another study exploring the genetics of sexual orientation is currently being conducted, and he assumed its researchers would incorporate these new findings into their study, but it will still probably be years until that report is completed.
As for exactly what locating these genes would mean, Mustanski said, "Finding the specific genes would have implications beyond uncovering the cause of homosexuality. Their identification would also greatly advance our understanding of human variation, evolution and brain development."
Mustanski also placed importance on studies focusing on women. "As with many things," he said, "females tend to be studied last and it would be important to start looking at female sexuality."
http://www.planetout.com/news/article.html?2005/01/21/5
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URL for Mothers' genetic skew linked to gay sons / methylation -- Lij, 17:16:30 01/23/05 Sun (ca-01.cinergycom.net/216.135.2.28)
Mothers' genetic skew linked to gay sons
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Zimmer on Hamer's God Gene -- Lij, 12:06:10 02/12/05 Sat (ca-01.cinergycom.net/216.135.2.28)
SCIENTIFIC AMERICAN, October, 2004 - A review of The God Gene: How Faith Is Hard-wired Into Our Genes, a book by Dean Hamer. Review by Carl Zimmer
By page 77 of The God Gene, Dean H. Hamer has already disowned the title of his own book. He recalls describing to a colleague his discovery of a link between spirituality and a specific gene he calls “the God gene.” His colleague raised her eyebrows. “Do you mean there's just one?” she asked. “I deserved her skepticism,” Hamer writes. “What I meant to say, of course, was 'a' God gene, not 'the' God gene.”
Of course. Why, the reader wonders, didn't Hamer call his book A God Gene? That might not have been as catchy, but at least it wouldn't have left him contradicting himself.
Whatever you want to call it, this is a frustrating book. The role that genes play in religion is a fascinating question that's ripe for the asking. Psychologists, neurologists and even evolutionary biologists have offered insights about how spiritual behaviors and beliefs emerge from the brain. It is reasonable to ask, as Hamer does, whether certain genes play a significant role in faith. But he is a long way from providing an answer.
Hamer, a geneticist at the National Cancer Institute, wound up on his quest for the God gene by a roundabout route. Initially he and his colleagues set out to find genes that may make people prone to cigarette addiction. They studied hundreds of pairs of siblings, comparing how strongly their shared heredity influenced different aspects of their personality. In addition to having their subjects fill out psychological questionnaires, the researchers also took samples of DNA from some of them. Hamer then realized that this database might let him investigate the genetics of spirituality.
He embarked on this new search by looking at the results of certain survey questions that measured a personality trait known as self-transcendence, originally identified by Washington University psychiatrist Robert Cloninger. Cloninger found that spiritual people tend to share a set of characteristics, such as feeling connected to the world and a willingness to accept things that cannot be objectively demonstrated. Analyzing the cigarette study, Hamer confirmed what earlier studies had found: heredity is partly responsible for whether a person is self-transcendent or not. He then looked at the DNA samples of some of his subjects, hoping to find variants of genes that tended to turn up in self-transcendent people. His search led him to a gene known as VMAT2. Two different versions of this gene exist, differing only at a single position. People with one version of the gene tend to score a little higher on self-transcendence tests. Although the influence is small, it is, Hamer claims, consistent. About half the people in the study had at least one copy of the self-transcendence boosting version of VMAT2, which Hamer dubs the God gene.
Is the God gene real? The only evidence we have to go on at the moment is what Hamer presents in his book. He and his colleagues are still preparing to submit their results to a scientific journal. It would be nice to know whether these results can withstand the rigors of peer review. It would be nicer still to know whether any other scientists can replicate them. The field of behavioral genetics is littered with failed links between particular genes and personality traits. These alleged associations at first seemed very strong. But as other researchers tried to replicate them, they faded away into statistical noise. In 1993, for example, a scientist reported a genetic link to male homosexuality in a region of the X chromosome. The report brought a huge media fanfare, but other scientists who tried to replicate the study failed. The scientist's name was Dean Hamer.
To be fair, it should be pointed out that Hamer offers a lot of details about his study in The God Gene, along with many caveats about how hard it is to establish an association between genes and behavior. But given the fate of Hamer's socalled gay gene, it is strange to see him so impatient to trumpet the discovery of his God gene. He is even eager to present an intricate hypothesis about how the God gene produces self-transcendence. The gene, it is well known, makes membrane covered containers that neurons use to deliver neurotransmitters to one another. Hamer proposes that the God gene changes the level of these neurotransmitters so as to alter a person's mood, consciousness and, ultimately, self-transcendence. He goes so far as to say that the God gene is, along with other faith-boosting genes, a product of natural selection. Self-transcendence makes people more optimistic, which makes them healthier and likely to have more kids.
These speculations take up the bulk of The God Gene, but in support Hamer only offers up bits and pieces of research done by other scientists, along with little sketches of spiritual people he has met. It appears that he has not bothered to think of a way to test these ideas himself. He did not, for example, try to rule out the possibility that natural selection has not favored self-transcendence, but some other function of VMAT2. (Among other things, the gene protects the brain from neurotoxins.) Nor does Hamer rule out the possibility that the God gene offers no evolutionary benefit at all. Sometimes genes that seem to be common thanks to natural selection turn out to have been spread merely by random genetic drift. Rather than address these important questions, Hamer simply declares that any hypothesis about the evolution of human behavior must be purely speculative. But this is simply not true. If Hamer wanted, he could have measured the strength of natural selection that has acted on VMAT2 in the past. And if he did find signs of selection, he could have estimated how long ago it took place. Other scientists have been measuring natural selection this way for several years now and publishing their results in major journals.
The God Gene might have been a fascinating, enlightening book if Hamer had written it 10 years from now-after his link between VMAT2 and self-transcendence had been confirmed by others and after he had seriously tested its importance to our species. Instead the book we have today would be better titled: A Gene That Accounts for Less Than One Percent of the Variance Found in Scores on Psychological Questionnaires Designed to Measure a Factor Called Self-Transcendence, Which Can Signify Everything from Belonging to the Green Party to Believing in ESP, According to One Unpublished, Unreplicated Study.
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Report in Nature details disease density of sex chromosome and surprises about X inactivation -- Lijdrec, 17:20:31 03/18/05 Fri (ca-02.cinergycom.net/216.135.2.29)
X Sequence Published
Report in Nature details disease density of sex chromosome and surprises about X inactivation | By Stephen Pincock
An international collaboration led by Britain's Wellcome Trust Sanger Institute will publish on Thursday (March 17) an almost complete sequence of the human X chromosome that offers, among many new insights, a better picture of how sex chromosomes evolved. A second paper in the same issue reveals some surprises about X inactivation of genes.
The Sanger Institute's Mark Ross and colleagues in the US and Germany determined 99.3% of the chromosome's euchromatic sequence and found 1,098 genes, including 399 "new" genes and 99 cancer-testis antigen genes.
But more than simply improving our understanding of individual genes, the sequence offers a powerful insight into the evolution of the chromosome itself, Ross told reporters at a press conference in London. "We can see the way evolution has shaped the chromosomes that determine our gender to give them their unique properties," he said. "The X chromosome is definitely the most extraordinary in the human genome."
Ross and colleagues offer some comparison of the sequence with that of the chicken to explore the development of the X chromosome from an autosome, which is thought to have occurred something like 300 million years ago. "Comparing the sequence of human X as it is with what is known about the sequences of other animal chromosomes allows you to tell where the X chromosome came from," said Robin Lovell-Badge from the National Institute for Medical Research, who wasn't involved in the study. "They've done some of that, but there's a lot more to be done."
Looking at more recent evolutionary history, the authors compared the human X chromosome with other mammalian sequences, finding nine major blocks of homology between human and mouse X chromosomes and 11 between human and rat. "The homology blocks occupy almost the entirety of each X chromosome, confirming the remarkable degree of conserved synteny of this chromosome within the eutherian mammalian lineage," they write.
The team's analysis revealed what coauthor Richard Gibbs from Baylor College of Medicine called "a lot of interesting local stories." "But maybe the message is not so much about surprise findings as the wealth of data," Gibbs told The Scientist. "It's mind-blowing the amount of biochemical data that has been generated."
The X chromosome has revealed itself to be quite different to autosomes, Lovell-Badge told The Scientist. "Compared with the autosomes that have been sequenced, it is relatively gene poor, which is interesting. It looks different to other chromosomes, so that's going to be interesting to study further."
One other difference is the relative density of disease related genes on the X, said Nature senior editor Chris Gunter, who wrote a News and Views article on the results. "It is the case that it is overrepresented with known disease genes," she told The Scientist. The sequence will be invaluable for identifying the genes for other known X-linked diseases, speakers at the press conference said.
The authors also note that LINE1 repeat elements cover a third of the X chromosome, "with a distribution that is consistent with their proposed role as way stations in the process of X-chromosome inactivation."
In the second paper, Laura Carrel from Pennsylvania State University College of Medicine, and Huntington Willard from Duke University, Durham, North Carolina, present a comprehensive profile of X-chromosome inactivation, the process by which genes on one X chromosome in female mammals are silenced in individual cells.
They found that about 75% of X-linked genes are permanently silent and about 15% permanently escape inactivation and are thus expressed at twice the level in women as in men. An additional 10% show variable patters of inactivation, they write.
"This suggests a remarkable and previously unsuspected degree of expression heterogeneity among females," Carrel and Willard write, and could explain some sexually dimorphic traits.
This finding also points to the future direction genomics should take, said Steve Jones, professor of genetics at University College London, who was not involved in the research. "All the action in genetics in the future will not be in the anatomy of the genome, which this sequencing is, but in physiology."
"It's not the structure that's important," he told The Scientist. "It's the regulation and the function."
Links for this article
M.T. Ross et al. "The DNA sequence of the human X chromosome." Nature 2005; 434:325-337.
http://www.nature.com
L. Carrel, HF Willard. "X-inactivation profile reveals extensive variability in X-linked gene expression in females," Nature 2005; 434:400-404.
http://www.nature.com
C. Holding, "Spreading key to X inactivation," The Scientist, February 23, 2004.
http://www.biomedcentral.com/news/20040223/01
Mark Ross
http://www.sanger.ac.uk/Teams/Team61/
Robin Lovell-Badge
http://www.nimr.mrc.ac.uk/devgen/
Richard Gibbs
http://www.bcm.edu/pa/gibbs.htm
C. Gunter. "She moves in mysterious ways," Nature 2005;434:279-280.
http://www.nature.com
Laura Carrel
http://fred.hmc.psu.edu/ds/retrieve/fred/investigator/lcarrel
Huntington Willard
http://www.genome.duke.edu/people/faculty/willard
Steve Jones
http://www.ucl.ac.uk/biology/new/admin/staffpages/jones/jones.h tm
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