A gene variant has been identified that appears to be associated with female-to-male transsexuality – the feeling some women have that they belong to the opposite sexBiological attributes and legal categories used to classify humans as male, female, intersex or other categories, primarily associated with physical and physiological features including chromosomes, genetic expression, hormone levels and function, and reproductive/sexual anatomy..
While such complex behaviour is likely the result of multiple genes, environmental and cultural factors, the researchers say the discovery suggests that transsexuality does have a genetic component.
The variation is in the gene for an enzyme called cytochrome P17, which is involved in the metabolism of sex hormonesHormones, such as oestrogen and testosterone, affecting sexual and reproductive development or function.. Its presence leads to higher than average tissue concentrations of maleA sex, usually assigned at birth, and based on chromosomes (e.g. XY), gene expression, hormone levels and function, and reproductive/sexual anatomy (e.g. penis, testicles). and femaleA sex, usually assigned at birth, and based on chromosomes (e.g. XX), gene expression, hormone levels and function, and reproductive/sexual anatomy (e.g. vagina, uterus). sex hormonesHormones, such as oestrogen and testosterone, affecting sexual and reproductive development or function., which may in turn influence early brain development.
Clemens Tempfer and his colleagues at the Medical University of Vienna in Austria discovered the variant after analysing DNA samples from 49 female-to-male (FtM)May refer to a person assigned female at birth whose gender is male all or part of the time; transitioning-to-male; female-to-male spectrum. and 102 male-to-female (MtF)May refer to a person assigned male at birth whose gender is female all or part of the time; transitioning-to-female; female-to-male spectrum. transsexuals, as well as 1669 non-transsexual controls.
The variant was more common in men than women, although it doesn’t seem to be implicated in MtF transsexuality as the proportion of MtF transsexuals with it was similar to that in non-transsexual men. In women, however, there were some differences: 44% of FtM transsexuals carried it, compared with 31% of non-transsexual women.
Testosterone boost
While there are many women with the variant who are not transsexualThis is typically used to describe people who identify as transgender who are transitioning toward the gender with which they identify. This may include socially presenting (e.g., clothing, hair, mannerisms, overall gender expression) as the gender with which they identify, or it may include more extensive changes like taking hormones and/or surgical procedures to modify their body. and many FtM transsexuals who lack it, the finding raises the possibility that the variant makes women more likely to feel that their bodies are of the wrong sexBiological attributes and legal categories used to classify humans as male, female, intersex or other categories, primarily associated with physical and physiological features including chromosomes, genetic expression, hormone levels and function, and reproductive/sexual anatomy., and that this is a result of their brains having been exposed to higher than average levels of sex hormonesHormones, such as oestrogen and testosterone, affecting sexual and reproductive development or function. during development.
“It may increase the likelihood that people will become transsexual”, says Tempfer. But he stresses that their cultural environment is also important.
“The present study found that a mutant gene that ultimately results in higher testosterone levels is overrepresented in female-to maleA sex, usually assigned at birth, and based on chromosomes (e.g. XY), gene expression, hormone levels and function, and reproductive/sexual anatomy (e.g. penis, testicles). transsexualism”, says Mikael Landén of the Karolinska Institute in Stockholm, Sweden.
“This is in line with what we previously know about masculinisation of the brain and is therefore less likely to be a chance finding”, he says. “Hence, the study is important and adds to the notion that gender identity• One’s innermost concept of self as male or female or both or neither – how individuals perceive themselves and what they call themselves. One’s gender identity can be the same or different than the sex assigned at birth. Individuals are conscious of this between the ages 18 months and 3 years. Most people develop a gender identity that matches their biological sex. For some, however, their gender identity is different from their biological or assigned sex. Some of these individuals choose to socially, hormonally and/or surgically change their sex to more fully match their gender identity.
• The gender to which one feels one belongs.
• Internal and psychological sense of oneself as a woman, a man, both, in between, or neither.
is influenced by sex hormonesHormones, such as oestrogen and testosterone, affecting sexual and reproductive development or function. early in life, and that certain gene combinations make individuals more vulnerable to aberrant effects”.
Motive fears
However, Janett Scott, former president of the Beaumont Society, a UK support group for transgender• Sometimes used as an umbrella to describe anyone whose identity or behaviour falls outside of stereotypical gender norms. More narrowly defined, it refers to an individual whose gender identity does not match their assigned birth gender. Being transgender does not imply any specific sexual orientation (attraction to people of a specific gender). Therefore, transgender people may additionally identify with a variety of other sexual identities as well.
• An umbrella term used to include transsexual people, transvestites and cross-dressers, as in “the transgender community.”
• This is an umbrella term that applies to anyone who does not feel that their gender identity (e.g., identifying as male, female, or other) matches their anatomical/bio- logical sex.
• An umbrella term for people whose gender identity and/or expression differs from that of their sex assigned at birth. Transgender people may or may not alter their bodies to better fit with their gender identity through means such as hormones or surgery. Some intersex people identify as transgender but the two are not the same. Identities such as transsexual or transvestite are distinct sub-categories of transgender and should not be used as synonyms. Should only be used as an adjective e.g. ‘transgender people’. The word “Transgendered” is used by some people but its use is discouraged.
people, is concerned that positing a biological basis for transsexuality may encourage people to try and cure it.
“Nature may have made us the way that we are, but nurture is what gives us a problem”, she says.
Tempfer strongly denies any such motive for his research: “That is completely out of the question”, he says.
Nonetheless, he says, if other gene variants with a stronger association to transsexuality are identified, establishing a diagnosis might become easier. This might allow gender reassignmentThe process by which an individual reassigns their gendered appearance. surgery or hormone therapy to start earlier in life.
Author – Linda Geddes
Original posting date – 29 July 2008
Source – https://www.newscientist.com/article/dn14424-transsexuality-gene-makes-women-feel-like-men/