Sex chromosome aberrations and transsexualism

Clinical features and prevalence of Klinefelter syndrome in transgender individuals: A systematic review

OBJECTIVE

Previous studies have suggested a higher prevalence of Klinefelter syndrome amongst transgender individuals. We undertook a systematic review to determine the prevalence of Klinefelter syndrome amongst transgender individuals presumed male at birth and summarize the clinical features and potential treatment implications for individuals with Klinefelter syndrome commencing gender-affirming hormone therapy.

DESIGN

Using preferred reporting items for systematic review and meta-analysis guidelines, we searched EMBASE, MEDLINE and the Cochrane Central Register of Controlled Trials (CENTRAL) up to 31 December 2021. All studies reporting on the prevalence or clinical features of transgender individuals with Klinefelter syndrome were included. This study is registered with the International Prospective Register of Systematic Reviews, number CRD42021227916.

RESULTS

Our search strategy retrieved 11 cohort studies comprising 1376 transgender individuals. In all, 14 of 1376 (1.02%) individuals were diagnosed with Klinefelter syndrome. Based on the seven studies in which karyotype was undertaken in all individuals, the prevalence is 9/1013 (0.88%; 95% CI, 0.41%-1.68%). Case reports highlight unique treatment considerations in this population, including azoospermia, venous thromboembolism, and monitoring of breast cancer and bone health.

CONCLUSIONS

Compared to the general population, observational studies document a higher prevalence of Klinefelter syndrome amongst transgender individuals, though underdiagnosis in the general population limits conclusions. Routine karyotype in transgender people initiating gender-affirming hormone therapy is not supported unless clinical features of Klinefelter syndrome, such as small testicular volume, or hypergonadotropic hypogonadism are present. Transgender individuals with Klinefelter syndrome need to manage a unique risk profile if they desire feminizing gender-affirming hormone therapy.

Gender Dysphoria Publication Trends: A Bibliometric Analysis between 1900 and 2018

Objective Research on gender dysphoria (GD) has been growing over the last decades with increasing interest in understanding and characterizing the causal relationships between psychological, genetics, hormonal, and sociocultural factors. Changes and acceptance of this condition as non-pathologic have led to significant changes in general perspective and its management over time. Our objective is to carry out a bibliometric analysis to know the publication trends and quality of evidence related to gender dysphoria.

Methods A systematic search and critical review of the literature was carried out between January 1900 and December 2018 to perform a bibliometric analysis. Research was done in the following databases: OVID, PubMed, EMBASE, Scopus, Web of Science and Google Scholar. The medical subject headings (MeSh) terms used were: gender dysphoria; and surgery and psychology. The results were plotted using the VOSviewer version 1.6.8. Statistical analyses were performed with the IBM SPSS, Version 25.0.

Results A total of 1,239 manuscripts were identified, out of which 1,041 were selected. The average number of cited times per year per manuscript is 1.84 (interquartile range [IQR] 0-2.33). The average impact index was 47.8 (IQR 20-111.6). The median of total citations per manuscript was 3 (IQR 0-33.1), and the highest number of citations per manuscript was 484. Most publications focus on the psychological aspects of GD, and there is a significant amount of manuscripts related to social and anthropological issues. Most articles have a low level of scientific evidence.

Conclusion There is a great amount of published literature on GD; however, there is a significant level of disagreement in many respects on this topic. Regarding surgical gender-affirmation, there is a lack of information supported by high level of evidence to uphold the emerging expansion of medical practices.

Should chromosomal analysis be performed routinely during the baseline evaluation of the gender affirmation process? The outcomes of a large cohort of gender dysphoric individuals

The role of genetics in the etiology of gender dysphoria (GD) is an important yet understudied area. Yet whether genetic analysis should be carried out during the gender affirmation process at all is a matter of debate. This study aims to evaluate the cytogenetic and molecular genetic findings of individuals with GD. We retrospectively reviewed the medical records of individuals with GD who were followed up in a tertiary clinic. After the exclusion criteria were applied, the study sample consisted of 918 individuals with GD; 691 of whom had female-to-male (FtM) and 227 male-to-female (MtF) GD. The cytogenetic analysis revealed that 223 out of 227 (98.2%) individuals with MtF GD had the 46,XY karyotype, while 683 out of 691 (98.8%) individuals with FtM GD had the 46,XX karyotype. In the Y chromosome microdeletion analysis, azospermic factor c (AZFc) deletion was detected in only two individuals with MtF GD. Our findings suggest that there are few chromosomal abnormalities in individuals with GD. Thus, this research calls into question both the role of chromosomal abnormalities in GD etiology and why the application of chromosomal analysis is in Turkey a routine part of the baseline evaluation of GD.

Sexual differentiation of the human hypothalamus: Relationship to gender identity and sexual orientation

Gender identity (an individual's perception of being male or female) and sexual orientation (heterosexuality, homosexuality, or bisexuality) are programmed into our brain during early development. During the intrauterine period in the second half of pregnancy, a testosterone surge masculinizes the fetal male brain. If such a testosterone surge does not occur, this will result in a feminine brain. As sexual differentiation of the brain takes place at a much later stage in development than sexual differentiation of the genitals, these two processes can be influenced independently of each other and can result in gender dysphoria. Nature produces a great variability for all aspects of sexual differentiation of the brain. Mechanisms involved in sexual differentiation of the brain include hormones, genetics, epigenetics, endocrine disruptors, immune response, and self-organization. Furthermore, structural and functional differences in the hypothalamus relating to gender dysphoria and sexual orientation are described in this review. All the genetic, postmortem, and in vivo scanning observations support the neurobiological theory about the origin of gender dysphoria, i.e., it is the sizes of brain structures, the neuron numbers, the molecular composition, functions, and connectivity of brain structures that determine our gender identity or sexual orientation. There is no evidence that one's postnatal social environment plays a crucial role in the development of gender identity or sexual orientation.

Molecular Karyotyping in Children and Adolescents with Gender Dysphoria

Purpose: The presence of a disorder of sexual development (DSD) acts as a diagnostic specifier for gender dysphoria (GD) under DSM-5, while the International Classification of Diseases (ICD)-10 specifically states that its equivalent diagnosis, gender identity disorder (GID), must not be the result of a chromosomal abnormality. For these reasons, routine karyotyping has been previously advocated in the clinical work-up of children and adolescents with suspected GD or GID. However, the utility of such testing remains unclear.

Methods: The results of routine molecular karyotyping were analyzed in 128 patients attending our Australian statewide pediatric gender service from 2013 to 2016. Karyotyping was performed using an Illumina BeadChip platform and provided information on both sex chromosome composition and copy number variation (CNV).

Results: No sex chromosome abnormalities directly suggestive of a DSD were discovered. The rate of CNVs among our patient cohort was 8.6% (11/128), similar to that previously reported for the general population. Unexpectedly, three trans male patients shared the same CNV, involving an almost identical 400 kbp deletion on chromosome 15q11.2. The frequency of this deletion within birth-assigned females in our cohort (3/69; 4.3%) was significantly higher than that within local control populations (0.3%; Fisher's exact test p-value=0.002), suggesting a possible association between 15q11.2 deletions and trans male identity.

Conclusion: Routine molecular karyotyping failed to detect any occult DSD and indicated that the rate of CNVs was similar to that of the general population. Given these findings, we suggest that molecular karyotyping has minimal clinical utility in the routine management of children and adolescents with GD.

Transsexualism: A Different Viewpoint to Brain Changes

Transsexualism refers to a condition or belief which results in gender dysphoria in individuals and makes them insist that their biological gender is different from their psychological and experienced gender. Although the etiology of gender dysphoria (or transsexualism) is still unknown, different neuroimaging studies show that structural and functional changes of the brain result from this sexual incongruence. The question here is whether these reported changes form part of the etiology of transsexualism or themselves result from transsexualism culture, behaviors and lifestyle. Responding to this question can be more precise by consideration of cultural neuroscience concepts, particularly the culture–behavior–brain (CBB) loop model and the interactions between behavior, culture and brain. In this article, we first review the studies on the brain of transgender people and then we will discuss the validity of this claim based on the CBB loop model. In summary, transgender individuals experience change in lifestyle, context of beliefs and concepts and, as a result, their culture and behaviors. Given the close relationship and interaction between culture, behavior and brain, the individual’s brain adapts itself to the new condition (culture) and concepts and starts to alter its function and structure.

Adolescents with gender dysphoria

Young people with gender dysphoria are increasingly seen by pediatric endocrinologists. Mental health child specialists assess the adolescent and give advice about psychological or medical treatment. Provided they fulfill eligibility and readiness criteria, adolescents may receive pubertal suspension, consisting of using gonadotrophin-releasing hormone analogs, later followed by cross-sex hormones (sex steroids of the experienced gender). If they fulfill additional criteria, they may have various types of gender affirming surgery. Current issues involve safety aspects. Although generally considered safe in the short-term, the long-term effects regarding bone health and cardiovascular risks are still unknown. Therefore, vigilance is warranted during and long after completion of the last gender affirming surgeries. The timing of the various treatment steps is also under debate: instead of fixed age limits, the cognitive and emotional maturation, along with the physical development, are now often considered as more relevant.

Twenty years of endocrinologic treatment in transsexualism: analyzing the role of chromosomal analysis and hormonal profiling in the diagnostic work-up

OBJECTIVE

To demonstrate that adequate pubertal history, physical examination, and a basal hormone profile is sufficient to exclude disorders of sexual development (DSD) in adult transsexuals and that chromosomal analysis could be omitted in cases of unremarkable hormonal profile and pubertal history.

DESIGN

Retrospective chart analysis.

SETTING

Endocrine outpatient clinic of a psychiatric research institute.

PATIENT(S)

A total of 475 subjects (302 male-to-female transsexuals [MtF], 173 female-to-male transsexuals [FtM]). Data from 323 (192 MtF/131 FtM) were collected for hormonal and pubertal abnormalities. Information regarding chromosomal analysis was available for 270 patients (165 MtF/105 FtM).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Pubertal abnormalities, menstrual cycle, and hormonal irregularities in relation to chromosomal analysis conducted by karyotype or hair root analysis.

RESULT(S)

In the MtF group, 5.2% of the patients reported pubertal irregularities and 5.7% hormonal abnormalities, and in the FtM group 3.8% and 19.1%, respectively. Overall chromosomal abnormality in both groups was 1.5% (2.9% in the FtM and 0.6% in the MtF group). The aneuploidies found included one gonosomal aneuploidy (45,X[10]/47,XXX[6]/46,XX[98]), two Robertsonian translocations (45,XXder(14;22)(q10;q10)), and one Klinefelter syndrome (47,XXY) that had already been diagnosed in puberty.

CONCLUSION(S)

Our data show a low incidence of chromosomal abnormalities and thus question routine chromosomal analysis at the baseline evaluation of transsexualism, and suggest that it be considered only in cases of abnormal history or hormonal examination.

Familiality of gender identity disorder in non-twin siblings

Familial studies and reports of co-occurrence of gender identity disorder (GID) within a family may help to clarify the question of whether transsexualism is a familial phenomenon. In a sample of 995 consecutive transsexual probands (677 male-to-female [MF] and 318 female-to-male [FM]), we report 12 pairs of transsexual non-twin siblings (nine pairs of MF siblings, two pairs of MF-FM siblings, and one pair of FM siblings). The present study doubles the number of case reports of co-occurrence of transsexualism in non-twin siblings available in the literature. According to our data, the probability that a sibling of a transsexual will also be transsexual was 4.48 times higher for siblings of MF than for siblings of FM transsexual probands, and 3.88 times higher for the brothers than for the sisters of transsexual probands. Moreover, the prevalence of transsexualism in siblings of transsexuals (1/211 siblings) was much higher than the range expected according to the prevalence data of transsexualism in Spain. The study suggests that siblings of transsexuals may have a higher risk of being transsexual than the general population, and that the risk is higher for brothers than sisters of transsexuals, and for siblings of MF than FM transsexuals. Nevertheless, the risk is low.

A polymorphism of the CYP17 gene related to sex steroid metabolism is associated with female-to-male but not male-to-female transsexualism

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.

INTERVENTION(S)

Buccal swabs and multiplex polymerase chain reaction on a microarray system.

MAIN OUTCOME MEASURE(S)

Analysis of the CYP17 -34 T>C SNP.

RESULT(S)

CYP17 -34 T>C SNP allele frequencies were statistically significantly different between FtM transsexuals and female controls (CYP17 T: 55/98 [56%] and CYP17 C: 43/98 [44%] versus CYP17 T: 1253/1826 [69%] and CYP17 C: 573/1826 [31%], respectively). In accordance, genotype distributions were also different between FtM transsexuals and female controls using a recessive genotype model (CYP17 T/T+T/C: 39/49 [80%] and C/C 10/49 [20%] vs. CYP17 T/T+T/C: 821/913 [90%] and C/C 92/913 [10%], respectively). The CYP17 -34 T>C allele and genotype distributions were not statistically significantly different between MtF transsexuals and male controls. Of note, the CYP17 -34 T>C allele distribution was gender-specific among controls (CYP17 C: males; 604 of 1512 [40%] vs. females; 573 of 1826 [31%]). 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.

Sexual differentiation of the human brain: relevance for gender identity, transsexualism and sexual orientation

Male sexual differentiation of the brain and behavior are thought, on the basis of experiments in rodents, to be caused by androgens, following conversion to estrogens. However, observations in human subjects with genetic and other disorders show that direct effects of testosterone on the developing fetal brain are of major importance for the development of male gender identity and male heterosexual orientation. Solid evidence for the importance of postnatal social factors is lacking. In the human brain, structural diferences have been described that seem to be related to gender identity and sexual orientation.

Absence of microdeletions in the azoospermia-factor region of the Y-chromosome in viennese men seeking assisted reproduction

PURPOSE

The azoospermia-factor region of the Y-chromosome is essential for spermatogenesis in humans. In the literature, a wide range is given for the frequency of microdeletions in this region. The purpose of this study was to evaluate our own population of patients.

METHODS

During a two-year period at Vienna Medical School, all male patients (n = 383) seeking assisted reproduction were screened for microdeletions. Thirty-three men had azoospermia and 154 severe oligozoospermia. Genomic DNA was prepared from peripheral lymphocytes and polymerase chain reaction analysis of the azoospermia-factor region was performed using the Promega kit.

RESULTS

No case tested positive for azoospermia-factor microdeletions. In all cases amplification of 18 non-polymorphic sequence tagged sites was obtained.

CONCLUSIONS

Y-chromosome microdeletions do not seem to be an important factor for male infertility in our patients. This suggests that screening should be restricted to men with azoospermia or severe oligozoospermia only.