From zyklonb99@my-deja.com Thu Jul 15 19:24:40 1999
Newsgroups: alt.tv.pol-incorrect
Subject: Researcher say "No fag gene."
From: zyklonb99@my-deja.com
Date: Fri, 16 Jul 1999 02:24:40 GMT

Search for Homosexuality Gene Fails

If there is such a thing as a gene for homosexuality, the most
intensive search yet has failed to find it in its most likely hiding
place.  Researchers are reporting today that a close look at a key
segment of the male X chromosome revealed no link to sexual
orientation. But other experts say the findings are hardly the last
word on the controversial issue.  The report, appearing in the journal
Science, is another setback for the field known as behavior genetics,
in which researchers try to find stretches of DNA that influence
personality traits in the same way that other bits of genetic material
code for physical traits such as eye color.  Most experts suspect that
genes do play a role, and several behavior- related genes, or groups of
genes, have been proposed. But so far none of these candidate links has
been clearly established.  A 1993 study proposed a genetic factor in
gay male orientation could be found on the X chromosome, which males
inherit from their mothers. That study, led by geneticist Dean Hamer at
the National Cancer Institute, seemed consistent with other research.
In addition, an influential, though never duplicated, 1991 study by
Salk Institute researcher Simon LeVay found anatomical differences
between the brains of gay and straight men.  The study released today
doesn't address the fundamental question of whether DNA can influence,
if not determine, sexual orientation.  The researchers, led by clinical
neurologists George Rice and George Ebers at the University of Western
Ontario, focused on just one part of the male chromosome, identified by
a genetic signpost known as Xq28.  They chose that region of the genome
because ``the most compelling'' scientific evidence so far had traced
male sexual orientation to the Xq28 position, researchers said.  ``We
were testing a very specific hypothesis,'' said study co-author Neil
Risch at Stanford University.  Researchers began by placing ads in two
Canadian gay news magazines seeking families with at least two gay
brothers. They eventually found 48 families willing to provide blood
samples for genetic analysis, including 46 with two gay brothers in
each and two families with three gay brothers each.  The families with
three gay brothers were each counted as having three gay sibling pairs,
producing a total of 52 pairs of DNA samples. A gay interviewer
affirmed the sexual orientation of the study subjects by questioning
them at the time blood samples were drawn.  The scientists then
conducted a detailed molecular analysis, hunting for common gene forms
near Xq28 that might have a significant bearing on sexual orientation.
In the end, no such sequences were found.  Michael Bailey, associate
professor of psychology at Northwestern University, who found strong
evidence of genetic links to homosexuality in a 1991 study of identical
twins, called the new study ``certainly relevant, but not decisive.''
LeVay, now an independent author in Los Angeles of books including
``Queer Science,'' said he remains convinced by other strands of
evidence that genetics have a bearing on homosexuality.  ``What this
study throws into question is whether that includes this particular
gene on the X chromosome,'' he said. ``Beyond that, it's an open
question.''
©1999 San Francisco Chronicle Page A5


Research Casts Doubt on 'Gay Gene' Theory
Study Finds Nothing Within X Chromosome That Predicts Male
Homosexuality
By Rick Weiss
Washington Post Staff Writer
Friday, April 23, 1999; Page A12
The latest effort to confirm lingering scientific hints that some gay
men inherit their homosexuality from their mothers has come up empty-
handed, researchers reported yesterday.
The inability to detect a link between male homosexuality and a
specific, maternally inherited genetic pattern calls into question a
pair of scientifically and politically charged studies that had found
evidence of the world's first "gay gene."
But the researcher who led the original gene experiments immediately
criticized the new study as being designed in a way that made it
virtually impossible to detect its genetic target. And other scientists
cautioned that larger and better studies will be needed to answer the
question of whether any single gene has a notable influence on sexual
orientation -- a behavior so complex as to almost certainly be under
the control of many different genes and environmental factors.
"I think the jury is still out," said Elliot Gershon, chairman of
psychiatry and a professor of human genetics at the University of
Chicago, who helped conduct a 1998 study that yielded its own
frustratingly ambiguous results about the genetics of homosexuality.
"All of these studies may be essentially accurate, and until we have
hundreds of gay men enrolled in studies we are not going to get a firm
answer."
Recent research has found a variety of intriguing, if still
unconfirmed, biological differences between homosexuals and
heterosexuals -- including differences in the sizes of various brain
parts -- suggesting there may be biological underpinnings to these
behavioral variants. Separately, studies of twins and other siblings
have suggested that genetic factors account for 40 percent to 60
percent of the odds that a person will be gay or straight.
Even if gay men never had children (and many do), such a gene could
persist in the population by being passed not only to sons but also to
daughters, who could later pass the gene to their sons. Alternatively,
the gene may be preserved by evolution because its primary function is
to make women sexually attracted to men -- but it occasionally gets
passed on to men.
The new work, led by George Rice of the University of Western Ontario
in London, Canada, challenges preliminary evidence that male
homosexuality is more likely to arise in men who inherent a certain
variant of the X chromosome -- one of 23 chromosomes a boy inherits
from his mother. Those initial findings, reported by Dean Hamer and
colleagues at the National Cancer Institute in 1993 and reaffirmed in
further research by the same team in 1995, stirred a huge amount of
controversy.
Some gay advocates cheered the finding as scientific proof of something
they had long felt: that their homosexuality was a deep-seated and
natural biological fact of life that ought to be accepted as a normal
part of the behavioral spectrum. Others, however, expressed fears that
the discovery of a gay gene could lead to prenatal testing and
abortions of affected fetuses, and perhaps an effort to develop "cures"
for the trait in adults.
A key and still hotly debated finding in Hamer's initial,
epidemiological research was that gay men tended to have more gay
relatives on the maternal side of their families compared to the
paternal side. That suggested that at least one gay gene might reside
on the X chromosome, which boys always inherit from their mother (the
father contributes a Y chromosome instead).
He searched for such a gene by studying the X chromosome in blood cells
of 40 gay men and their brothers. He found statistically reliable
evidence that a gene predisposing to male homosexuality resided in a
region of the X chromosome called Xq28, which contains about 400 genes.
Hamer's second study reaffirmed that finding, and he has since been
trying to find the specific gene that may be responsible.
Doubting those results, the Rice team performed genetic tests on 52 gay
men and their brothers, focusing on the Xq28 region. They report in
today's issue of the journal Science that nothing in that region
accurately predicts whether a man will be gay.
A gay gene may well exist elsewhere on the X chromosome, or perhaps on
any of the other pairs of chromosomes, the team concluded. But their
failure to confirm Hamer's results, they said, suggests that the best
candidate gay gene to date is either nonexistent or contributes very
little to the trait overall.
Hamer disagrees with that interpretation. Either by design or by
chance, he said, the gay men that Rice studied had a preponderance of
gay relatives on their fathers' side of the family. That suggests that,
to the extent these men's homosexuality was caused by genes, it was
largely inherited from their fathers.
These men probably harbor one or more gay genes somewhere in their
cells, Hamer said. But it makes no sense to study them in search of a
gay gene on the X chromosome, he said, since that chromosome is
inherited only from the mother.
David M. Smith, a spokesman for the Human Rights Campaign, a Washington-
based gay political organization with more than 300,000 members, warned
against getting overly obsessed with the genetics of homosexuality.
"In the final analysis it should not matter whether there is a
biological basis or there is not," Smith said. "Public policy should
treat all people fairly and equally."
© Copyright 1999 The Washington Post Company

Canada Study Casts Doubt On Idea Of 'Gay Gene'
By Maggie Fox, Health and Science Correspondent
WASHINGTON (Reuters) - Researchers in Canada cast doubt on the idea of
a ``gay gene'' Thursday, saying they had been unable to find any
genetic link between brothers who are homosexual.
In 1993, Dr. Dean Hamer and colleagues at the U.S. National Cancer
Institute provoked a worldwide furor when they reported they had found
evidence of a ``gay gene'' in men.
They had studied 40 pairs of gay brothers and found 33 of them shared a
particular sequence of the genetic codes on their X chromosomes, in an
area called Xq28. They said that pointed to a possible gay gene.
But in a study published in this week's Science, George Rice and
colleagues at the University of Western Ontario in London, Canada, said
they studied more pairs of gay brothers and found no evidence that they
shared some sort of mutation in that area.
``These results do not support an X-linked gene underlying male
homosexuality,'' Rice's team wrote in its report. But the team added
that the search should continue for any possible genetic cause of
homosexuality.
Men, in addition to their 22 pairs of matched chromosomes, have one X
and one Y chromosome. Women have two Xs.
Men inherit their X chromosomes from their mothers, and because they
have just one copy, are vulnerable to genetic defects carried on the X
chromosome such as color blindness and Fragile X syndrome, which causes
a form of mental retardation.
Hamer's team had noted a tendency for homosexuality to run in the
female line -- men whose mothers had gay brothers also tended to be
homosexual, the team reported. So it looked for an area on the X
chromosome that might be involved.
The team homed in on an area known as Xq28.
Rice's team tried to duplicate and expand on those results.
The team studied 52 sets of brothers in Canada who were both gay,
looking specifically at the Xq28 gene.
``We advertised in Canadian gay news magazines for families in which
there were at least two gay brothers,'' the team wrote.
It compared their genes to samples taken from 33 pairs of brothers who
had been gene-tested for multiple sclerosis.
But the researchers did not find any particular variation of the gene
that marked gays from non-gays. Gay brothers were not unusually likely
to share one of four variations of Xq28 that they looked for.
``It is unclear why our results are so discrepant from Hamer's original
study,'' the team wrote.
The researchers said it was possible there was another ``gay gene,'' as
the team only looked at one gene for its study.
But Rice's team also said that if homosexuality was a simple inherited
trait, it would be very likely to have been bred out -- because
homosexuals would be less likely to have children and pass on the
trait.
But studies dating back to the 1980s show some evidence that
homosexuality might run in families.
One study on identical twins, who share more of their genes than
regular siblings, found one twin was more likely to be gay if his twin
was, and another study found homosexual men were more likely to have
homosexual brothers even if they were not twins.
Other experts point out that being homosexual does not preclude having
children, so there would be no reason for a ''gay gene'' to have been
bred out.


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