Genes determine transsexuality

[Shana A]

Genes determine transsexuality

http://www.thehindu.com/holnus/099200905141151.htm

Sydney (IANS): The largest ever genetic study of transsexuals has established a link between gender identity and a gene involved in modifying the action of sex hormone testosterone.

From an early age people develop an inner sense of being male or female. Transsexuals however, identify with a physical sex opposite to their biological sex.

DNA samples were collected from 112 male to female transsexuals and researchers compared genetic differences with non transsexuals.

They discovered that male to female transsexuals were more likely to have a longer version of a gene which is known to modify the action of testosterone.

[Just Kate]

Profoundly interesting.  I cannot wait to read the actual journal article (once the Biological Psychiatry website comes back up).

[NicholeW.]

There was a good bit of pub about this study when it was announced last year. I believe if your interested enough, Inter, you can order a copy through Prince Henry Institute or UCLA, perhaps, if the Biological Psychiatry site is down for long.

[Just Kate]

I'll keep an eye out for the site to come back up for now, but if not, I'll look into taking your advice.

[Suzy]

I think this is a fascinating study, and would love to see more follow-up on it.

There are always other ethical implications, though.  If they found a link, could it lead to treatment where those with GID are "cured"?  Could it lead to selective abortions?  And on and on it goes.  Still I would love to see more work done.

Kristi

[GinaDouglas]

I'm not sure if "adaptive DNA" is the right term for it, but there are some elements of DNA that turns on and shuts off and different times.  I can't remember the exact term for it, this kind of if/then DNA; but it's the reason why there is such a huge variety of size and characteristics amongst dogs.  I'm thinking the term is something like "transitive DNA", but Googling that showed it's not the term.

Anyway, when science fully understands the role of this kind of DNA in humans, I am sure we will find many different genetic basises for transsexualism and ->-bleeped-<-.

[Janet_Girl]

The question comes to mind, would you take the testing if offered?  What if you tested negative, would you stop your transition?  Or would you believe in your own feelings?

And can science offer real proof GID exist to the fact that the rest of the world would accept it or us?

I would like to know myself, but it would not change a thing for me.

Janet

[Just Kate]

The question comes to mind, would you take the testing if offered?  What if you tested negative, would you stop your transition?  Or would you believe in your own feelings?

And can science offer real proof GID exist to the fact that the rest of the world would accept it or us?

I would like to know myself, but it would not change a thing for me.

Janet

This is an interesting question - the idea that, if the best scientific evidence said you were NOT a transsexual, would that change your mind concerning your own transition? 

I think it would depend strongly on how far one has gone, or more particularly, what one has already given up in order to become what one perceives to be oneself.  I imagine, the more one has given up, the less likely they will be convinced, under any circumstance, that they might not be what they believe themselves to be. 

cognitive dissonance > scientific evidence

After all, we aren't Vulcans. *shameless Star Trek reference*
[/quote]

[Lisbeth]

This is an interesting question - the idea that, if the best scientific evidence said you were NOT a transsexual, would that change your mind concerning your own transition? 

I recommend you study the term "statistical correlation." Correlation is not determination.

They discovered that male to female transsexuals were more likely to have a longer version of a gene which is known to modify the action of testosterone.

[GinaDouglas]

What if you tested negative, would you stop your transition?  Or would you believe in your own feelings?
Janet

It's not a hypothetical question for me.  When I first entered college, in 1978; and when I first entered grad school in 1989; I exhaustively researched transsexualism.  It was crystal clear, that scientifically I could not be considered to be transsexual, because I was sexually attracted exclusively to females.  At those times, I had more faith in science than I had in my own judgment; so I resolved to do my best to be the straight man that science told me I was.

Now, with regards to this test, I'd like to take it.  However, if the test was negative, I would think there was simply another test, as yet undiscovered, which would someday prove that I am in fact what I know myself to be.  You know, fool me once, fool me twice...

[Just Kate]

I recommend you study the term "statistical correlation." Correlation is not determination.

I'm quite familiar with this, but I do not see how my rephrasing of Janet's question implies a correlation vs causation problem.

EDIT: My question was independent of the study findings - I just found Janet's question interesting and took it the next step.

[Michelle.]

A study of 112 M2F's is the largest genetic study to date.

Well the conclusion of that article is correct,

"As with all genetic association studies, it will be important to replicate these findings in other populations," said Harley, an associate professor, according to a Prince Henry release.

Researchers are now planning even larger genetic studies and are investigating a wider range of genes that may be related to gender identity.

Let the further studies and ethical debates begin.

Notice the "other populations" and "Hindu...," was this an Indian study or Australian one?

Also is the variance in the size of the T-receptor gene the result of the gene itself, or a result of an in utereo condition?

[Annwyn]

Absolute hogwash.  It's like saying your religion is determined by your genes.  There's a lot more at play than genes.

I really hate my own field of study...

[ZoeB]

A polymorphism of the CYP17 gene related to sex steroid metabolism is associated with female-to-male but not male-to-female transsexualism Bentz E, Hefler L, Kaufmann U, Huber J, Kolbus A, Tempfer C Fertility and Sterility , Volume 90 , Issue 1 , Pages 56 - 59

OBJECTIVE: To assess the association between transsexualism and allele and genotype frequencies of the common cytochrome P450 (CYP) 17 -34 T>C single nucleotide polymorphism (SNP). DESIGN: Case-control study. SETTING: Academic research institution. PATIENT(S): 102 male-to-female (MtF) and 49 female-to-male (FtM) transsexuals, 756 male controls, and 915 female controls.
    ...
    The MtF transsexuals had an allele distribution equivalent to male controls, whereas FtM transsexuals did not follow the gender-specific allele distribution of female controls but rather had an allele distribution equivalent to MtF transsexuals and male controls. CONCLUSION(S): These data support CYP17 as a candidate gene of FtM transsexualism and indicate that loss of a female-specific CYP17 T -34C allele distribution pattern is associated with FtM transsexualism.

Androgen Receptor Repeat Length Polymorphism Associated with Male-to-Female Transsexualism by Hare at al Biological Psychiatry Volume 65, Issue 1, Pages 93-96 (1 January 2009)

Background

There is a likely genetic component to transsexualism, and genes involved in sex steroidogenesis are good candidates. We explored the specific hypothesis that male-to-female transsexualism is associated with gene variants responsible for undermasculinization and/or feminization. Specifically, we assessed the role of disease-associated repeat length polymorphisms in the androgen receptor (AR), estrogen receptor β (ERβ), and aromatase (CYP19) genes.
Methods

Subject-control analysis included 112 male-to-female transsexuals and 258 non-transsexual males. Associations and interactions were investigated between CAG repeat length in the AR gene, CA repeat length in the ERβ gene, and TTTA repeat length in the CYP19 gene and male-to-female transsexualism.
Results

A significant association was identified between transsexualism and the AR allele, with transsexuals having longer AR repeat lengths than non-transsexual male control subjects (p = .04). No associations for transsexualism were evident in repeat lengths for CYP19 or ERβ genes. Individuals were then classified as short or long for each gene polymorphism on the basis of control median polymorphism lengths in order to further elucidate possible combined effects. No interaction associations between the three genes and transsexualism were identified.
Conclusions

This study provides evidence that male gender identity might be partly mediated through the androgen receptor.

[Feever]

I would take the test.

In fact I would take almost any test to have some clinical proof to be able to hold in my hand to tell me why I feel the way I do.  Would it change my plans?  Probably not.  I know how I feel.

[Miniar]

I'd love to take the test, but seeing as this is a study in MtF transsexualism, I don't think it'd do any good.

I think it's obvious that some of this is genetically founded and I don't quite approve of my deep seeded personal identity being compared with "religion" which more often than not requires just taking scripture's (any religious scripture, not just the bible) word for it. Allthough, every religious text is originally written by man, a physical being, and affected by that man and his physical surroundings so there is a scientific basis for religion and understanding it might make scripture make more and better sense, and be something you'd better be able to trust....
But I'm getting WAY off topic here.

[NicholeW.]

It's not a hypothetical question for me.  When I first entered college, in 1978; and when I first entered grad school in 1989; I exhaustively researched transsexualism.  It was crystal clear, that scientifically I could not be considered to be transsexual, because I was sexually attracted exclusively to females.  At those times, I had more faith in science than I had in my own judgment; so I resolved to do my best to be the straight man that science told me I was.

Have to admit, Gina, I'm rather puzzled by your belief that "science" has determined that MTF transsexuals are "only" those who are attracted exclusively to males. Even some of the more rabid-supporters of a particularly rabid group of "classic transsexuals" admit attraction to women. And many of us are both intellectually bisexual and have had and continue to have not only attractions to both males and females but sexual relations with both as well.

There's a statistical correlation between bisexuality and females, at least a much greater occurrence of bisexuality among females than among males (some of that sould be admitting, sorta like the guys who believe that if they are dating or married to a woman and only have "stealth" sex with males that they remain "heterosexual".) Greater numbers of women tend to exemplfy a characteristic whereby they find that sexual attraction goes with the attraction to a particular partner. Thus, they will sometimes be "lesbian" and sometimes be "straight." (Which sounds to me a lot like bisexual.)

I am continuing not to see any correlation between "who I love or am attracted toward" and my sex. So I am puzzled by this constant refrain that "sexuality" somehow plays into a discussion of sex. Feel free to enlighten me, if you will, through PMs so as not to break the rhythm of the thread any more than this post has already done.

Thanks.

Nichole 

[Sandy]

Have to admit, Gina, I'm rather puzzled by your belief that "science" has determined that MTF transsexuals are "only" those who are attracted exclusively to males. Even some of the more rabid-supporters of a particularly rabid group of "classic transsexuals" admit attraction to women. And many of us are both intellectually bisexual and have had and continue to have not only attractions to both males and females but sexual relations with both as well.

There's a statistical correlation between bisexuality and females, at least a much greater occurrence of bisexuality among females than among males (some of that sould be admitting, sorta like the guys who believe that if they are dating or married to a woman and only have "stealth" sex with males that they remain "heterosexual".) Greater numbers of women tend to exemplfy a characteristic whereby they find that sexual attraction goes with the attraction to a particular partner. Thus, they will sometimes be "lesbian" and sometimes be "straight." (Which sounds to me a lot like bisexual.)

I am continuing not to see any correlation between "who I love or am attracted toward" and my sex. So I am puzzled by this constant refrain that "sexuality" somehow plays into a discussion of sex. Feel free to enlighten me, if you will, through PMs so as not to break the rhythm of the thread any more than this post has already done.

Thanks.

Nichole

I too used my heterosexual nature as proof that I wasn't a transsexual.  I liked girls not boys (then) and so how could I be a girl on the inside?  It drove my denial for a very long time.

Back then, at least from what I knew from the main stream press and stories I could get my hands on, gender identity and sexual orientation *were* linked and many considered them identical.  I think that is one of the reasons given for John Hopkins closing their gender clinic.  The so-called doctor that took over (I forgot is name) deemed transsexuality a mode of homosexuality and should be treated as such.  It broke my heart when I read that.  It meant that I was truly a pervert and not a "real" transsexual because the experts at JH said that no such thing existed.

Time/people/science moves on.  Things change.  That was then, this is now.

-Sandy (Thank Goddess!)

[Feever]

I too used my heterosexual nature as proof that I wasn't a transsexual.

This is exactly my case. 

I have never been attracted to a man, but I think that is possible that in the future I could be.

[Ms Jessica]

very interesting (especially since I'm a geneticist). 

I'll see if I can't get pdfs of the articles.  (the FTM one sounds interesting too)

WRT to Interalia's and Janet's discussion of "does a negative result change your mind about transition" I'd like to put it in perspective of a heritable disease: primary ciliary dyskinesia (PCD).  It's a multisystemic disease that affects, among other things, cilia in the respiratory system.  There are currently only two genes for which one can be tested to check for causative mutations.  However, mutations in the two implicated genes only account for something like 30 or 40% of all cases of PCD.  What about the other 60 to 70% of individuals with PCD but no mutations in the two known genes?  There are about 8 other genes (IIRC, it might be more) involved in the structure and function of cilia, so the current testing methodology is far from exhaustive.  As more is known about additional genes, then testing can improve.  The way it stands now, you can still be diagnosed with PCD even if you're mutation free in the two testable genes. 
Coming back to transsexualism: finding one gene involved in sex steroid receptors might be only the tip of a VERY big iceberg.  Mutations in the one gene can be perpetuated in a single population (google or wikipedia Founder Mutations for more info on this) but may not exist in other groups of people.  In other words, your negative test just means that's not the cause of your transsexualism, it doesn't mean you aren't trans.  If you have all the other symptoms for being trans, then guess what, you're trans.  All the genetic testing in the world doesn't have much to do with it.  There are genetic and environmental components to several things we don't understand well (such as autism). 

The nice thing about this study is that it's actual work looking at transsexuals.  Improving understanding of transsexualism and possible etiologies for being trans can go a long way to legitimizing us in the eyes of a non-tolerant society.  Although, as someone else said above, it might just also lead to more abortions.  I'll try to be optimistic though.  It is Friday, after all. 

Post Merge: May 15, 2009, 01:13:23 PM
I was able to download pdf's of both the Bentz et al and Hare et al articles.  If you're interested in getting them by email, send me a PM.