Notes[N1] Transsexual genes identified. News-Medical.net (Online). Monday, 27-Oct-2008.
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[N2] For a contrasting analysis and report of the same report, see the TS-Si.org article.

Genomic Association Study Identifies Genetic Basis for MtF Feminization. TS-Si News Service. TS-Si.org (Online). 27 October 2008.
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Citations[C1] Sex and gender: what is the difference? Britta N. Torgrimson and Christopher T. Minson. Editorial. Journal of Applied Physiology (J Appl Physiol) 99: 785-787, 2005. doi: 10.1152 / japplphysiol.00376.2005 8750-7587/05.
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Excerpt

IT IS CLEAR THAT SEX IS A key biological variable that should be considered in all basic physiological and biological research. However, despite a long history of interest in sex-based investigations, this topic has historically not been well studied. The current importance of sex research is obvious by the recent rise in articles reporting on sex-based biology across scientific journals, including the Journal of Applied Physiology. There are two terms being used in this contemporary dialogue to describe the sex-based research: "sex" and "gender." The term gender is becoming more common in scientific publications to describe biological variation traditionally assigned to sex, and this nonspecific language merits a standardized approach.

Increasingly, researchers are becoming aware of the appropriate use of the terms sex vs. gender. Still, some scientists are vaguely aware that a distinction exists between these terms or that this difference is an important one. The purpose of this article is to publicize the necessity for implementing a standardized use of the terms sex and gender in physiology. Thus this article will present a general history examining the transition in the frequency of use of the term gender instead of sex in physiology, present standard definitions by promoting the recommendation from the Institute of Medicine (IOM), and provide examples of appropriate use of these terms in reference to specific contexts.

Coming to a consensus in the use of terminology is a worthwhile endeavor for disciplines such as physiology that rely heavily on specific language to explain phenomena. Other disciplines, including psychology and anthropology, have put into practice distinguishing between the terms sex and gender in their discourse (4, 11, 12). As physiologists, we will likely find that adopting this distinction can only improve communication within as well as outside our discipline.

[C2] Sex and Gender: Same or Different? Part IV of Gender Construction in Everyday Life: Transsexualism (Abridged). Feminism & Psychology 10(1): 46-54 2000.
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Excerpt

Along the primrose path of childhood children learn something fundamental. At a most basic level they incorporate that Dads and Moms are designations with very different implications. Up front, it is accepted that Dads are men and Moms are women; that Dads and Moms do different things at home and elsewhere. Simultaneously children learn that boys play rough and girls play nice and they usually like to do different things. Then kids learn that boys grow up to be Dads and girls grow up to be Moms.

Interestingly, this is the standard pattern children incorporate even when they know these rules have exceptions. They almost always know families where its Mom who is the outside-the-home money earner and Dad who stays home, and where boys are nice and quiet while girls are hellions. The basic stereotypes, however, seem somehow branded on their psyche in the every day course of growing up. The input is from family, friends, media, religion and even politics. And most of middle-class society colludes, in turn, to transmit social and cultural normative expectations with essentially the same rules. With a certain degree of schooling and maturity children learn that the sexes to which we are referring are male and female. It further comes to be understood that male and female are terms used to incorporate a whole catalog of physical and behavioral differences.

[C3] Male-to-Female Transsexuals Have Female Neuron Numbers in a Limbic Nucleus. Frank P. M. Kruijver, Jiang-Ning Zhou, Chris W. Pool, Michel A. Hofman, Louis J. G. Gooren and Dick F. Swaab. The Journal of Clinical Endocrinology & Metabolism 85(5) 2034-2041.
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Abstract

Transsexuals experience themselves as being of the opposite sex, despite having the biological characteristics of one sex. A crucial question resulting from a previous brain study in male-to-female transsexuals was whether the reported difference according to gender identity in the central part of the bed nucleus of the stria terminalis (BSTc) was based on a neuronal difference in the BSTc itself or just a reflection of a difference in vasoactive intestinal polypeptide innervation from the amygdala, which was used as a marker. Therefore, we determined in 42 subjects the number of somatostatin-expressing neurons in the BSTc in relation to sex, sexual orientation, gender identity, and past or present hormonal status. Regardless of sexual orientation, men had almost twice as many somatostatin neurons as women (P < 0.006). The number of neurons in the BSTc of male-to-female transsexuals was similar to that of the females (P = 0.83). In contrast, the neuron number of a female-to-male transsexual was found to be in the male range. Hormone treatment or sex hormone level variations in adulthood did not seem to have influenced BSTc neuron numbers. The present findings of somatostatin neuronal sex differences in the BSTc and its sex reversal in the transsexual brain clearly support the paradigm that in transsexuals sexual differentiation of the brain and genitals may go into opposite directions and point to a neurobiological basis of gender identity disorder.

Introduction

ANIMAL experiments and observations in human brains have convincingly shown that sexual differentiation not only concerns the genitalia but also the brain (1, 2). The strongly connected and sexually differentiated hypothalamus, septum, bed nucleus of the stria terminalis (BST), and amygdala are implicated in sexually dimorphic patterns of reproductive and nonreproductive behaviors.

Gender identity (i.e. the feeling to be male or to be female) is an important trait of a subject. Transsexuals experience themselves as being of the opposite sex, despite having the biological characteristics of one sex. In line with the hypothesis that in transsexuals sexual differentiation of the brain contrasts with that of the genetic and physical characteristics of sex, our group has recently found that the size of the central subdivision of the BST (BSTc) was within the female range in genetically male-to-female transsexuals. In that study the, BSTc was defined on the basis of its vasoactive intestinal polypeptide innervation, which is probably mainly derived from the amygdala. A crucial question resulting from that study was, therefore, whether the difference according to gender in the BSTc is based on a neuronal difference in the BSTc itself or rather a reflection of a difference in innervation from the amygdala. To see whether the BSTc itself has a neuronal organization that is opposite to that of the genetic and genitalial characteristics of transsexuals, we determined the number of somatostatin (SOM)-expressing neurons in the BSTc, which is the major neuronal population in this structure.