Tuesday, August 10, 2010

sex/gender determination - not just XX or XY

Much ado has been made over the sex status of Nikki Araguz. Most people have an over simplified and misguided understanding of what determines male or female in mammals, and of the significance of biological sex/gender. In fact, genetically, physiologically, and pragmatically, sex/gender is only a minor biological attribute in human beings. There are even numerous biological variations that produce people who are neither strictly male or female. Some of the variations are primarily genetic in nature and some are hormonal conditions that are the product of specific genetic conditions. What is most important for people to understand though, is that nature can produce XX male people and XY female people under a variety of conditions, in addition to the usual XY male and XX female, plus numerous genetic intersex/hermaphroditic conditions, many of which involve mosaic sex chromosomes such as XXY, XYY, XXX, X0, 0Y, genetic mutations. Consequently, it is scientifically inaccurate for uninformed people like the attorney Chad Ellis, who represents Heather Delgado in her lawsuit against Nikki Araguz, to claim categorically that genes are the sole determinant of sex/gender and that such genetics render biological sex/gender immutable at conception. Such a claim by Chad Ellis is patently false, in addition to being uninformed.

Primarily sex/gender in humans is determined by a specific gene called the "sex determining region"(SRY) (1), where there is a specific protein containing the "testis determining factor"(TDF) (1). However this gene can exist in various mutated forms. One mutation called Swyer Syndrome (2) causes total "gonadal dysgenesis" and consequently produces an XY female person who is born with female genitalia, but without any internal gonads or a uterus. Another mutation translocates the TDF factor onto an X chromosome, which produces an XX male person, and is called "XX male syndrome"(3).

Nikki Araguz at about age nineteen
In addition to the testis determining factor, in order for a person to develop as a male, the gene that controls the androgen receptors in each cell must also function to produce male characteristics. When the gene for the androgen receptor doesn't function correctly, a condition called Androgen Insensitivity Syndrome (AIS) [4] occurs. The AIS mutation can cause either complete insensitivity to androgens (testosterone), or partial insensitivity to androgens. In cases of complete AIS, the person is born with female genitalia that includes a vagina, nondescript gonads in the position of ovaries without clear characteristics for either sex, but without a uterus. In cases of partial AIS, the person can be born with either ambiguous genitalia or with apparently male genitalia, but because such people do not respond to androgens, their genitals often don't develop any further after birth, at puberty, or during adulthood.

It seems apparent that Nikki Araguz was born with partial Androgen Insensitivity Syndrome, possibly with genitals that appeared relatively normal at birth, but which could not grow any further because her body doesn't respond to androgens (testosterone). The video documentary of Nikki Araguz that was made while she was in college at the age of about nineteen or twenty provides excellent evidence of her genetic condition. In the video Nikki Araguz has all the facial features and characteristics of any ordinary female, and a matching small stature and frame. Given the genetic condition Nikki Araguz was born with, there isn't any way that her body could ever develop into a fully adult male one because even exogenously provided testosterone would not have had any effect on her.

It should be noted that cells through every person's bodies have both androgen and estrogen receptors. Some areas of the body have specific estrogen or androgen receptors that produce obvious results. For example androgen receptors in facial hair follicles produce a facial beard when stimulated by androgens/testosterone. Consequently a person will develop a beard regardless of having an XX or XY sex chromosome pair if they are given testosterone and if they have working androgen receptors. This is why XX transsexual-men who are given testosterone develop beards and lowered voices. However, such testosterone treatment would not have any effect on someone with AIS, such as Nikki Araguz. Similarly, anyone with working estrogen receptors who is given adequate estrogen and progesterone will develop breasts, as is the case for transsexual-women who take estrogen.

As for Nikki Aarguz, even without genital reconstruction surgery, and despite presumptively having an XY sex chromosome pair (apparently not yet confirmed with DNA testing), she was never truly male because her body is only able to respond to hormones in a female manner. Given a full understanding of the science of sex determination, it seems that given a "reasonable person" standard, it makes complete sense for Nikki Araguz to be medically treated to enable her to live a fully female life since her body wasn't able to develop as a male at birth, or throughout her life, in any event. Hopefully the attorneys for Nikki Araguz will have the opportunity to present this level of expert scientific testimony to the Texas Court considering whether or not she should be considered legally female.

(1) sex-determining region - http://en.wikipedia.org/wiki/SRY

(2) swyer syndrome - http://en.wikipedia.org/wiki/Swyer_syndrome

(3) xx male syndrome - http://en.wikipedia.org/wiki/XX_male_syndrome

(4) androgen insensitivity syndrome - http://en.wikipedia.org/wiki/Androgen_insensitivity_syndrome

(5) x chromosome - http://en.wikipedia.org/wiki/Y_chromosome

1 comment:

  1. Thank you for pointing all this out - these details seem have been set aside in the reporting of this case.