Genetic control of typical and atypical sex development

Assessment of testicular function in boys and adolescents

OBJECTIVE

The hypothalamic-pituitary-testicular axis is characterised by the existence of major functional changes from its establishment in fetal life until the end of puberty. The assessment of serum testosterone and gonadotrophins and semen analysis, typically used in the adult male, is not applicable during most of infancy and childhood. On the other hand, the disorders of gonadal axis have different clinical consequences depending on the developmental stage at which the dysfunction is established. This review addresses the approaches to evaluate the hypothalamic-pituitary-testicular axis in the newborn, during childhood and at pubertal age.

DESIGN

We focused on the hormonal laboratory and genetic studies as well as on the clinical signs and imaging studies that guide the aetiological diagnosis and the functional status of the gonads.

RESULTS

Serum gonadotrophin and testosterone determination is useful in the first 3-6 months after birth and at pubertal age, whereas AMH and inhibin B are useful biomarkers of testis function from birth until the end of puberty. Clinical and imaging signs are helpful to appraise testicular hormone actions during fetal and postnatal life.

CONCLUSIONS

The interpretation of results derived from the assessment of hypothalamic-pituitary-testicular in paediatric patients requires a comprehensive knowledge of the developmental physiology of the axis to understand its pathophysiology and reach an accurate diagnosis of its disorders.

Pathological characteristics of SRY-negative 38,XX-DSD pigs: A family case report

Disorders of sex development (DSD) are congenital conditions characterized by atypical development of chromosomes, gonads, or anatomical sex. XX-DSD pigs disrupt the production of high-quality breeding pigs and impede the advancement of the pig industry. However, the etiology of XX-DSD pigs remains unclear. Systematic reports on the genetic and pathological characteristics of prepubescent XX-DSD pigs in familial contexts are sparse. This study aimed to investigate the genetic and pathological features of one-month-old XX-DSD pigs within a familial context and to provide phenotypic information to elucidate the pathogenic mechanisms of XX-DSD pigs. The findings revealed that inbreeding within the XX-DSD family may contribute to the pathogenesis of XX-DSD pigs. All XX-DSD pigs in the family had a chromosomal sex of female and were male pseudohermaphrodites. The degree of masculinization of the reproductive organs varied among XX-DSD pigs, demonstrating phenotypic heterogeneity. HE staining showed that the testes of prepubescent XX-DSD pigs contained vesicles in the seminiferous tubules, with or without vestigial germ cells. Ultrastructural analyses indicated that sertoli cells, leydig cells and germ cells in the testes of XX-DSD pigs exhibited pathological damage, confirming impaired testicular function. Immunofluorescence staining revealed high expression of SRY-box transcription factor 9 (SOX9) in XX-DSD pig testicular tissues, while forkhead box L2 (FOXL2) was minimally expressed. Disordered secretion of reproductive hormones in prepubescent XX-DSD pigs indicated abnormal hypothalamic-pituitary-gonadal axis (HPGA) function. This study elucidates the genetic and pathological characteristics of prepubescent XX-DSD pigs in familial case, providing valuable insights for further exploration of the pathogenic mechanisms underlying XX-DSD.

Whole-genome de novo sequencing reveals genomic variants associated with differences of sex development in SRY negative pigs

BACKGROUND

Differences of sex development (DSD) are congenital conditions in which chromosomal, gonadal, or phenotypic sex is atypical. In more than 50% of human DSD cases, a molecular diagnosis is not available. In intensively farmed pig populations, the incidence of XX DSD pigs is relatively high, leading to economic losses for pig breeders. Interestingly, in the majority of 38, XX DSD pigs, gonads still develop into testis-like structures or ovotestes despite the absence of the testis-determining gene (SRY). However, the current understanding of the molecular background of XX DSD pigs remains limited.

METHODS

Anatomical and histological characteristics of XX DSD pigs were analysed using necropsy and HE staining. We employed whole-genome sequencing (WGS) with 10× Genomics technology and used de novo assembly methodology to study normal female and XX DSD pigs. Finally, the identified variants were validated in 32 XX DSD pigs, and the expression levels of the candidate variants in the gonads of XX DSD pigs were further examined.

RESULTS

XX DSD pigs are characterised by the intersex reproductive organs and the absence of germ cells in the seminiferous tubules of the gonads. We identified 4,950 single-nucleotide polymorphisms (SNPs) from non-synonymous mutations in XX DSD pigs. Cohort validation results highlighted two specific SNPs, "c.218T > C" in the "Interferon-induced transmembrane protein 1 gene (IFITM1)" and "c.1043C > G" in the "Newborn ovary homeobox gene (NOBOX)", which were found exclusively in XX DSD pigs. Moreover, we verified 14 candidate structural variants (SVs) from 1,474 SVs, identifying a 70 bp deletion fragment in intron 5 of the WW domain-containing oxidoreductase gene (WWOX) in 62.5% of XX DSD pigs. The expression levels of these three candidate genes in the gonads of XX DSD pigs were significantly different from those of normal female pigs.

CONCLUSION

The nucleotide changes of IFITM1 (c.218T > C), NOBOX (c.1043 C > G), and a 70 bp deletion fragment of the WWOX were the most dominant variants among XX DSD pigs. This study provides a theoretical basis for better understanding the molecular background of XX DSD pigs. DSD are conditions affecting development of the gonads or genitalia. These disorders can happen in many different types of animals, including pigs, goats, dogs, and people. In people, DSD happens in about 0.02-0.13% of births, and in pigs, the rate is between 0.08% and 0.75%. Pigs have a common type of DSD where the animal has female chromosomes (38, XX) but no SRY gene, which is usually found on the Y chromosome in males. XX DSD pigs may look like both males and females on the outside and have testis-like or ovotestis (a mix of ovary and testis) gonads inside. XX DSD pigs often lead to not being able to have piglets, slower growth, lower chance of survival, and poorer meat quality. Here, we used a method called whole-genome de novo sequencing to look for variants in the DNA of XX DSD pigs. We then checked these differences in a larger group of pigs. Our results reveal the nucleotide changes in IFITM1 (c.218T > C), NOBOX (c.1043 C > G), and a 70 bp deletion fragment in intron 5 of the WWOX, all linked to XX DSD pigs. The expression levels of these three genes were also different in the gonads of XX DSD pigs compared to normal female pigs. These variants are expected to serve as valuable molecular markers for XX DSD pigs. Because pigs are a lot like humans in their genes, physiology, and body structure, this research could help us learn more about what causes DSD in people.

Gender Reassignment and the Role of the Laboratory in Monitoring Gender-Affirming Hormone Therapy

Transgender people experience distress due to gender incongruence (i.e., a discrepancy between their gender identity and sex assigned at birth). Gender-affirming hormone treatment (GAHT) is a part of gender reassignment treatment. The therapeutic goals of the treatment are to develop the physical characteristics of the affirmed gender as far as possible. Guidelines have been developed for GAHT, which recommend dosage as well as different formulations of oestrogen and testosterone for treatment. Questions arise about the metabolic side effects of hormone treatment. Establishing reference ranges for common analytes in transgender individuals remains a task for laboratory medicine. It has been suggested once GAHT is commenced, the reference ranges for affirmed gender are reported for red blood cells, haemoglobin and haematocrit. For transgender assigned-female-at-birth (AFAB) people, testosterone concentrations are recommended to be within the reference interval established for cisgender men and for transgender assigned-male-at-birth (AMAB) people, estradiol concentrations are within the reference range for cisgender women. Sex-specific reference ranges are available for certain laboratory tests, and these may be organ (e.g., heart)-specific. Transgender-specific reference ranges may be a requirement for such tests. Laboratories may need to make decisions on how to report other tests in the transgender population, e.g., eGFR. Interpretation of further tests (e.g., reproductive hormones) can be individualized depending on clinical information. Electronic medical record systems require fields for gender identity/biological sex at birth so that laboratory results can be flagged appropriately. In this review, we aim to summarise the current position of the role of the laboratory in the clinical care of the transgender individual. Prior to the review, we will summarise the genetics of sex determination, the aetiology of gender incongruence, and the recommendations for GAHT and monitoring for the transgender population.

Familial 46, XY Disorder of Sexual Development identified in a Ph+BCR::ABL1P210+ Acute Lymphoblastic Leukemia septuagenarian female with RCBTB2::LPAR6 fusion gene: a case report

Background

Familial 46, XY Disorder of Sexual Development (DSD) was discovered in a Ph+, BCR::ABL1P210+ Acute Lymphoblastic Leukemia (ALL) female with RCBTB2::LPAR6 fusion gene. Siblings developing 46, XY DSD are extremely rare. Patients with 46, XY DSD have much higher rates of gonadal cancers. Nevertheless, the incidence of hematologic malignancies in patients with DSDs has received little attention. RCBTB2::LPAR6 is a rarely reported fusion gene in ALL.

Case presentation

Herein, we report a rare case of a newly diagnosed Ph+, BCR::ABL1P210+ ALL patient who was 77 years old and female by social sex. Whole Exome Sequencing (WES) and RNA sequencing revealed TET2 and NF1 mutations in addition to a rarely reported RCBTB2::LPAR6 fusion gene and 17 other genes with uncertain clinical significance. The patient was surprisingly found to have a male karyotype. On ultrasound, neither the uterus nor the ovaries were discernible. A detailed family and marital history revealed that the patient had undergone surgery at an early age for an unexplained inguinal mass. She had slow pubertal development, scanty menstruation, and few overtly feminine characteristics. She had three marriages, but none succeeded in getting pregnant. The patient had never sought therapy for infertility due to the inaccessibility of medical treatment and a lack of medical knowledge. Her sister, 73 years old and female by social sex, who had amenorrhea in adolescence and was unable to conceive, had the same experience. To our surprise, she also had a male karyotype.

Conclusions

Due to the absence of long-term social attention and follow-up, studies on the incidence of hematologic malignancies in patients with 46, XY DSD are incredibly uncommon. Siblings developing 46, XY DSD is extremely rare. We report the oldest patient diagnosed with 46, XY DSD. There have not yet been any reports of familial 46, XY DSD with a concurrent diagnosis of Ph+BCR::ABL1P210+ ALL with a rarely reported RCBTB2::LPAR6 fusion gene.

Cytogenomic description of a Mexican cohort with differences in sex development

BACKGROUND

Differences in Sex Development (DSD) is a heterogeneous group of congenital alterations that affect inner and/or outer primary sex characters. Although these conditions do not represent a mortality risk, they can have a severe psycho-emotional impact if not appropriately managed. The genetic changes that can give rise to DSD are diverse, from chromosomal alterations to single base variants involved in the sexual development network. Epidemiological studies about DSD indicate a global frequency of 1:4500-5500, which can increase to 1:200-300, including isolated anatomical defects. To our knowledge, this study is the first to describe epidemiological and genetic features of DSD in a cohort of Mexican patients of a third-level care hospital.

METHODS

Descriptive and retrospective cross-sectional study that analyzed DSD patients from 2015 to 2021 attended a Paediatric Hospital from Mexico City.

RESULTS

One hundred one patients diagnosed with DSD were registered and grouped into different entities according to the Chicago consensus statement and the diagnosis defined by the multidisciplinary group. Of the total, 54% of them belong to the chromosomal DSD classification, 16% belongs to 46, XX and 30% of them belongs to the 46, XY classification.

CONCLUSION

The frequency for chromosomal DSDs was consistent with the literature; however, we found that DSD 46, XY is more frequent in our cohort, which may be due to the age of the patients captured, the characteristics of our study population, or other causes that depend on the sample size.

Clinical and gonadal transcriptome analysis of 38,XX disorder of sex development pigs†

Pigs serve as a robust animal model for the study of human diseases, notably in the context of disorders of sex development (DSD). This study aims to investigate the phenotypic characteristics and molecular mechanisms underlying the reproductive and developmental abnormalities of 38,XX ovotestis-DSD (OT-DSD) and 38,XX testis-DSD (T-DSD) in pigs. Clinical and transcriptome sequencing analyses were performed on DSD and normal female pigs. Cytogenetic and SRY analyses confirmed that OT/T-DSD pigs exhibited a 38,XX karyotype and lacked the SRY gene. The DSD pigs had higher levels of follicle-stimulating hormone, luteinizing hormone, and progesterone, but lower testosterone levels when compared with normal male pigs. The reproductive organs of OT/T-DSD pigs exhibit abnormal development, displaying both male and female characteristics, with an absence of germ cells in the seminiferous tubules. Sex determination and development-related differentially expressed genes shared between DSD pigs were identified in the gonads, including WT1, DKK1, CTNNB1, WTN9B, SHOC, PTPN11, NRG1, and NXK3-1. DKK1 is proposed as a candidate gene for investigating the regulatory mechanisms underlying gonadal phenotypic differences between OT-DSD and T-DSD pigs. Consequently, our findings provide insights into the molecular pathogenesis of DSD pigs and present an animal model for studying into DSD in humans.

Worldwide cohort study of 46, XY differences/disorders of sex development genetic diagnoses: geographic and ethnic differences in variants

Differences/disorders of sex development (DSDs) in individuals with a 46, XY karyotype are a group of congenital disorders that manifest as male gonadal hypoplasia or abnormalities of the external genitalia. Approximately 50% of patients with 46, XY DSDs cannot obtain a molecular diagnosis. The aims of this paper were to review the most common causative genes and rare genes in patients with 46, XY DSDs, analyze global molecular diagnostic cohorts for the prevalence and geographic distribution of causative genes, and identify the factors affecting cohort detection results. Although the spectrum of genetic variants varies across regions and the severity of the clinical phenotype varies across patients, next-generation sequencing (NGS), the most commonly used detection method, can still reveal genetic variants and aid in diagnosis. A comparison of the detection rates of various sequencing modalities revealed that whole-exome sequencing (WES) facilitates a greater rate of molecular diagnosis of the disease than panel sequencing. Whole-genome sequencing (WGS), third-generation sequencing, and algorithm advancements will contribute to the improvement of detection efficiency. The most commonly mutated genes associated with androgen synthesis and action are AR, SR5A2, and HSD17B3, and the most commonly mutated genes involved in gonadal formation are NR5A1 and MAP3K1. Detection results are affected by differences in enrollment criteria and sequencing technologies.

Pleasurable and problematic receptive anal intercourse and diseases of the colon, rectum and anus

The ability to experience pleasurable sexual activity is important for human health. Receptive anal intercourse (RAI) is a common, though frequently stigmatized, pleasurable sexual activity. Little is known about how diseases of the colon, rectum, and anus and their treatments affect RAI. Engaging in RAI with gastrointestinal disease can be difficult due to the unpredictability of symptoms and treatment-related toxic effects. Patients might experience sphincter hypertonicity, gastrointestinal symptom-specific anxiety, altered pelvic blood flow from structural disorders, decreased sensation from cancer-directed therapies or body image issues from stoma creation. These can result in problematic RAI - encompassing anodyspareunia (painful RAI), arousal dysfunction, orgasm dysfunction and decreased sexual desire. Therapeutic strategies for problematic RAI in patients living with gastrointestinal diseases and/or treatment-related dysfunction include pelvic floor muscle strengthening and stretching, psychological interventions, and restorative devices. Providing health-care professionals with a framework to discuss pleasurable RAI and diagnose problematic RAI can help improve patient outcomes. Normalizing RAI, affirming pleasure from RAI and acknowledging that the gastrointestinal system is involved in sexual pleasure, sexual function and sexual health will help transform the scientific paradigm of sexual health to one that is more just and equitable.

A role for TRPC3 in mammalian testis development

SOX9 is a key transcription factor for testis determination and development. Mutations in and around the SOX9 gene contribute to Differences/Disorders of Sex Development (DSD). However, a substantial proportion of DSD patients lack a definitive genetic diagnosis. SOX9 target genes are potentially DSD-causative genes, yet only a limited subset of these genes has been investigated during testis development. We hypothesize that SOX9 target genes play an integral role in testis development and could potentially be causative genes in DSD. In this study, we describe a novel testicular target gene of SOX9, Trpc3. Trpc3 exhibits high expression levels in the SOX9-expressing male Sertoli cells compared to female granulosa cells in mouse fetal gonads between embryonic day 11.5 (E11.5) and E13.5. In XY Sox9 knockout gonads, Trpc3 expression is markedly downregulated. Moreover, culture of E11.5 XY mouse gonads with TRPC3 inhibitor Pyr3 resulted in decreased germ cell numbers caused by reduced germ cell proliferation. Trpc3 is also expressed in endothelial cells and Pyr3-treated E11.5 XY mouse gonads showed a loss of the coelomic blood vessel due to increased apoptosis of endothelial cells. In the human testicular cell line NT2/D1, TRPC3 promotes cell proliferation and controls cell morphology, as observed by xCELLigence and HoloMonitor real-time analysis. In summary, our study suggests that SOX9 positively regulates Trpc3 in mouse testes and TRPC3 may mediate SOX9 function during Sertoli, germ and endothelial cell development.

COUP-TFII regulates early bipotential gonad signaling and commitment to ovarian progenitors

BACKGROUND

The absence of expression of the Y-chromosome linked testis-determining gene SRY in early supporting gonadal cells (ESGC) leads bipotential gonads into ovarian development. However, genetic variants in NR2F2, encoding three isoforms of the transcription factor COUP-TFII, represent a novel cause of SRY-negative 46,XX testicular/ovotesticular differences of sex development (T/OT-DSD). Thus, we hypothesized that COUP-TFII is part of the ovarian developmental network. COUP-TFII is known to be expressed in interstitial/mesenchymal cells giving rise to steroidogenic cells in fetal gonads, however its expression and function in ESGCs have yet to be explored.

RESULTS

By differentiating induced pluripotent stem cells into bipotential gonad-like cells in vitro and by analyzing single cell RNA-sequencing datasets of human fetal gonads, we identified that NR2F2 expression is highly upregulated during bipotential gonad development along with markers of bipotential state. NR2F2 expression was detected in early cell populations that precede the steroidogenic cell emergence and that retain a multipotent state in the undifferentiated gonad. The ESGCs differentiating into fetal Sertoli cells lost NR2F2 expression, whereas pre-granulosa cells remained NR2F2-positive. When examining the NR2F2 transcript variants individually, we demonstrated that the canonical isoform A, disrupted by frameshift variants previously reported in 46,XX T/OT-DSD patients, is nearly 1000-fold more highly expressed than other isoforms in bipotential gonad-like cells. To investigate the genetic network under COUP-TFII regulation in human gonadal cell context, we generated a NR2F2 knockout (KO) in the human granulosa-like cell line COV434 and studied NR2F2-KO COV434 cell transcriptome. NR2F2 ablation downregulated markers of ESGC and pre-granulosa cells. NR2F2-KO COV434 cells lost the enrichment for female-supporting gonadal progenitor and acquired gene signatures more similar to gonadal interstitial cells.

CONCLUSIONS

Our findings suggest that COUP-TFII has a role in maintaining a multipotent state necessary for commitment to the ovarian development. We propose that COUP-TFII regulates cell fate during gonad development and impairment of its function may disrupt the transcriptional plasticity of ESGCs. During early gonad development, disruption of ESGC plasticity may drive them into commitment to the testicular pathway, as observed in 46,XX OT-DSD patients with NR2F2 haploinsufficiency.

Support for affirmative actions to increase inclusivity of intersex* persons at an Austrian medical university

BACKGROUND

Since the ruling handed down by the Austrian Constitutional Court in 2018 intersex variation has been recognized under Austrian law as a "third sex". In order to ensure that people with intersex variation are not discriminated against based on their group membership affirmative actions (i.e., proactive practices to avert discrimination) can be implemented. The current study explored whether students and employees at an Austrian medical university know about intersex variation. Furthermore, the study investigated what affirmative actions are practiced at the medical university to be inclusive for intersex persons and students' and employees' support for such affirmative actions.

METHODS

All students and employees of a medical university in Austria were invited by e-mail to participate at the current study that included a self-constructed knowledge test on intersex variation with ten true-false questions. On five-point Likert scales participants reported for each of twelve listed affirmative actions whether they had seen a certain affirmative action at their university and how important they thought the implementation of an affirmative action was. Finally, participants' gender, age, sexual orientation, highest level of education, and nationality was assessed. A cluster analysis was performed to determine groups of people with different degrees of support for affirmative actions for intersex persons.

RESULTS

220 students (62% cisgender women, 38% cisgender men) and 200 employees (72% cisgender women, 28% cisgender men) participated. Participants responded correctly to three out of ten knowledge test questions. The cluster analysis revealed that participants could be clustered as heterosexual cisgender women (Cluster 1; 55%), heterosexual cisgender men (Cluster 2; 30%), or sexual minority cisgender women and men (Cluster 3; 15%). Sexual minority persons knew more about intersex variation than did heterosexual participants. On average, affirmative actions for the inclusivity of intersex people have not been encountered (M = 1.5, SD = 0.4) at the studied university. Participants, especially those in Cluster 3, believed that the listed actions are moderately important.

CONCLUSIONS

At the medical university many actions should be taken to increase inclusivity for intersex people. Increasing the knowledge of university staff and students concerning intersex might help increase their support for such actions.

The past and future of "sex genes"

Much later than the discovery of "sex chromosomes" and of "sex hormones", genetics started delivering detailed explanations of sex-determining developmental pathways. Despite increasing knowledge of biological processes, concepts and theories about sex development are never based on facts alone. There are inevitable entanglements of biological description and changing cultural assumptions and they play a key role in how sex genes are framed and interpreted in biological research. In this review article we first focus on the early 20th century biology that worked in a hormone-based paradigm. Genetic explanations emerged later, first on the basis of sex chromosomes; starting in the 1980s, on the basis of genes. We highlight orthodox views of female development, which saw the default pathway of human sex development. We will show how recent findings in biology challenge it. The article discusses the interactions of causal claims in science with cultural assumption about gender and outlines three influential strands of critical feminist philosophy of science: the critique of genetic determinism and genetic essentialism, of dualist assumptions, and of an androcentric bias in the conception of research strategies. In the final section we suggest key agenda points of future genetic research on sex determination.