Androgen imprinting of the brain in animal models and humans with intersex disorders: review and recommendations

Association between the 2D:4D ratio and schizophrenia

OBJECTIVE

To investigate the potential association between the ratio of the second digit length to the fourth digit length (2D:4D) and schizophrenia, to provide evidence regarding the pathogenesis of schizophrenia.

METHODS

In this study, we enrolled 843 patients with schizophrenia (387 men and 456 women), all of whom met the diagnostic criteria of the Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV), and 1050 normal healthy controls (477 men and 573 women). The digit lengths of both hands were measured in all subjects and the 2D:4D ratio was analyzed.

RESULTS

In the healthy controls, the 2D:4D ratio was sexually dimorphic, with a larger value in women than in men. In addition, the 2D:4D ratio in the schizophrenia patients was significantly larger than in the healthy controls. The 2D:4D ratio of the right hand was more sexually dimorphic than the left hand. Furthermore, the difference in 2D:4D ratios between the male patients and male controls was significantly larger than in their female counterparts.

CONCLUSIONS

By analyzing the 2D:4D ratio and considering alternative factors related to schizophrenia, our findings support the hypothesis that there are abnormal cerebral conditions in schizophrenia patients.

Sexual Orientation in Individuals With Congenital Adrenal Hyperplasia: A Systematic Review

Congenital adrenal hyperplasia (CAH) is a genetic condition of the steroidogenic enzymes in the adrenal cortex normally leading to variable degrees of cortisol and aldosterone deficiency as well as androgen excess. Exposure to androgens prenatally might lead to ambiguous genitalia. The fetal brain develops in traditional male direction through a direct action of androgens on the developing nerve cells, or in the traditional female direction in the absence of androgens. This may indicate that sexual development, including sexual orientation, are programmed into our brain structures prenatally. The objective of this study was to perform a systematic review of the literature, investigating sexual orientation in individuals with CAH. The study also aimed at identifying which measures are used to define sexual orientation across studies. The review is based on articles identified through a comprehensive search of the OVIDMedline, PsycINFO, CINAHL, and Web of Science databases published up to May 2019. All peer-reviewed articles investigating sexual orientation in people with CAH were included. Quantitative, qualitative, and mixed methods were considered, as well as self-, parent-, and third-party reports, and no age or language restrictions were enforced on publications. The present review included 30 studies investigating sexual orientation in patients with CAH assigned female at birth (46, XX) (n = 927) or assigned male at birth (46, XY and 46, XX) (n = 274). Results indicate that assigned females at birth (46, XX) with CAH had a greater likelihood to not have an exclusively heterosexual orientation than females from the general population, whereas no assigned males at birth (46, XY or 46, XX) with CAH identified themselves as non-heterosexual. There was a wide diversity in measures used and a preference for unvalidated and self-constructed interviews. Hence, the results need to be interpreted with caution. Methodological weaknesses might have led to non-heterosexual orientation being overestimated or underestimated. The methodological challenges identified by this review should be further investigated in future studies.

Evidence that prenatal testosterone transfer from male twins reduces the fertility and socioeconomic success of their female co-twins

During sensitive periods in utero, gonadal steroids help organize biological sex differences in humans and other mammals. In litter-bearing species, chromosomal females passively exposed to prenatal testosterone from male littermates exhibit altered physical and behavioral traits as adults. The consequences of such effects are less well understood in humans, but recent near-doubling of twinning rates in many countries since 1980, secondary to advanced maternal age and increased reliance on in vitro fertilization, means that an increasing subset of females in many populations may be exposed to prenatal testosterone from their male co-twin. Here we use data on all births in Norway (n = 728,842, including 13,800 twins) between 1967 and 1978 to show that females exposed in utero to a male co-twin have a decreased probability of graduating from high school (15.2%), completing college (3.9%), and being married (11.7%), and have lower fertility (5.8%) and life-cycle earnings (8.6%). These relationships remain unchanged among the subsets of 583 and 239 females whose male co-twin died during the first postnatal year and first 28 days of life, respectively, supporting the interpretation that they are due primarily to prenatal exposure rather than to postnatal socialization effects of being raised with a male sibling. Our findings provide empirical evidence, using objectively measured nation-level data, that human females exposed prenatally to a male co-twin experience long-term changes in marriage, fertility, and human capital. These findings support the hypothesis of in utero testosterone transfer between twins, which is likely affecting a small but growing subset of females worldwide.

Gene regulatory mechanisms underlying sex differences in brain development and psychiatric disease

The sexual differentiation of the mammalian nervous system requires the precise coordination of the temporal and spatial regulation of gene expression in diverse cell types. Sex hormones act at multiple developmental time points to specify sex-typical differentiation during embryonic and early development and to coordinate subsequent responses to gonadal hormones later in life by establishing sex-typical patterns of epigenetic modifications across the genome. Thus, mutations associated with neuropsychiatric conditions may result in sexually dimorphic symptoms by acting on different neural substrates or chromatin landscapes in males and females. Finally, as stress hormone signaling may directly alter the molecular machinery that interacts with sex hormone receptors to regulate gene expression, the contribution of chronic stress to the pathogenesis or presentation of mental illness may be additionally different between the sexes. Here, we review the mechanisms that contribute to sexual differentiation in the mammalian nervous system and consider some of the implications of these processes for sex differences in neuropsychiatric conditions.

Controversies of Sex Re-assignment in Genetic Males with Congenital Inadequacy of the Penis

Sex assignment in 46XY genetic male children with congenital inadequacy of the penis (CIP) is controversial. Traditionally, children with penile length less than 2 cm at birth are considered unsuitable to be raised as males. They are typically re-assigned to female-sex and feminizing genitoplasty is usually done in infancy. However, the concept of cerebral androgen imprinting has caused paradigm shift in the philosophy of sex re-assignment. Masculinization of the brain, rather than length of the penis, is the modern criterion of sex re-assignment in CIP. This review summarizes the current understanding of the complex issue. In 46XY children with CIP, male-sex assignment appears appropriate in non-hormonal conditions such as idiopathic micropenis, aphallia and exstrophy. Female-sex re-assignment appears acceptable in complete androgen insensitivity (CAIS), while partial androgen insensitivity syndrome (PAIS) patients are highly dissatisfied with the assignment of either sex. Children with 5-alpha reductase deficiency are likely to have spontaneous penile lengthening at puberty. Hence, they are better raised as males. Although female assignment is common in pure gonadal dysgenesis, long-term results are not known to justify the decision.

Neonatal Sex Assignment in Disorders of Sex Development: A Philosophical Introspection

Management of ambiguous genitalia is highly controversial. This condition was known previously as intersex and presently as disorders of sex development (DSD). There is no consensus regarding the choice, timing and method of sex assignment in neonates with DSD. Consensus conferences could not unify the views of various stakeholders and third parties. This article philosophically examines the nature and origin of such controversies. Misconception, bias and conflicting priorities are identified as the three cardinal sources of controversies. Conceptual duality of sexes, confused notion of sex and gender, bias towards penetrative intercourse, conflict between utopian ideals and reality, unwillingness to compromise are identified as perpetuators of controversies. Suggestions are made regarding sex assignment in various types of DSD based on the understanding of published literature and the author's personal experience.

Regulation of testicular descent

Testicular descent occurs in two morphologically distinct phases, each under different hormonal control from the testis itself. The first phase occurs between 8 and 15 weeks when insulin-like hormone 3 (Insl3) from the Leydig cells stimulates the gubernaculum to swell, thereby anchoring the testis near the future inguinal canal as the foetus grows. Testosterone causes regression of the cranial suspensory ligament to augment the transabdominal phase. The second, or inguinoscrotal phase, occurs between 25 and 35 weeks, when the gubernaculum bulges out of the external ring and migrates to the scrotum, all under control of testosterone. However, androgen acts mostly indirectly via the genitofemoral nerve (GFN), which produces calcitonin gene-related peptide (CGRP) to control the direction of migration. In animal models the androgen receptors are in the inguinoscrotal fat pad, which probably produces a neurotrophin to masculinise the GFN sensory fibres that regulate gubernacular migration. There is little direct evidence that this same process occurs in humans, but CGRP can regulate closure of the processus vaginalis in inguinal hernia, confirming that the GFN probably mediates human testicular descent by a similar mechanism as seen in rodent models. Despite increased understanding about normal testicular descent, the common causes of cryptorchidism remain elusive.

Practical approach to steroid 5alpha-reductase type 2 deficiency

The aim of this article is to review the literature on steroid 5alpha-reductase type 2 deficiency (5α-RD2) to provide clinicians with information to guide their management of patients with this disorder. The 5alpha-reductase type 2 is encoded by the 5alpha-reductase type 2 gene (SRD5A2) on chromosome 2 and is predominantly expressed in external genital tissues and the prostate. Mutations of the SRD5A2 gene leads to an uncommon autosomal recessive disorder affecting sexual differentiation in individuals with 46,XY karyotype; their phenotype can range from almost normal female structures to a distinct male phenotype with ambiguous genitalia at birth. These phenotypes result from impaired conversion of testosterone to dihydrotestosterone due to mutations in the SRD5A2 gene. Patients exhibit virilization at puberty without breast development, which is often accompanied by gender identity change from female to male. More than 40 mutations have been reported in all five exons of the SRD5A2 gene. Phenotype-genotype correlations for 5α-RD2 have not been well established. The newborn phenotypes of male pseudohermaphrodites with 5α-RD2, partial androgen insensitivity syndrome (PAIS), or 17β-hydroxysteroid dehydrogenase type 3 (17β-HSD3) enzyme deficiency may be indistinguishable. We conclude that steroid 5α-RD2 should be included in the differential diagnosis of newborns with 46,XY DSD. It is important that the diagnosis be made in infancy by biochemical and molecular studies before gender assignment or any surgical intervention because these patients should be considered males at birth.

Long-term psychosocial adjustments, satisfaction related to gender and the family equations in disorders of sexual differentiation with male sex assignment

PURPOSE

The varied management and counseling in disorders of sexual differentiation (DSD) depends a lot on the socioeconomic structure. A follow-up study was designed to evaluate the outcome in terms of patient satisfaction with strong socio-cultural issues.

METHOD

Of the 1,134 DSD patients being followed up in pediatric intersex clinic, 60 adolescents and adults assigned male sex in childhood were called for follow-up. They were interviewed for psychosocial and family adjustments including level of acceptance of gender, social relationships and future expectations.

RESULTS

The ages ranged from 15 to 25 years (mean, 19.3 ± 3.7 years). The disorders were male pseudo hermaphrodite (MPH)-43, mixed gonadal dysgenesis (MGD)-3, true hermaphrodite (TH)-7 and congenital adrenal hyperplasia (CAH)-7. Of all patients, 85% (51/60) felt satisfied with their gender assignment; 76.9% (46/60) did not feel comfortable with the opposite sex. Penile erections; ejaculation and masculine voice were present in 53, 44 and 47 patients. Facial hair was normal; sparse and absent in 16, 26 and 18 patients, respectively. Stretched penile length was 2.5-9 cm (median, 5.5 cm) and 16/60 patients were satisfied with their penile length; 28 patients required redo surgeries for scrotum diverticulum (1), proximal penile diverticulum (1), stricture urethra (2), hair in the urethra (3), vaginal pouch dilatation (1), orchiopexy (2), residual chordee correction (3), distal urethroplasty (4), urethral fistula repair (21), mastectomy (6) and testicular prosthesis (4). Family support was available to all 85% (51/60) of the patients who had good family relationships. However, only 15% (9/60) felt that they fitted into society. Peer relationships were considered 'good' by 43/60 and poor by 17/60. Two patients had got married and 44.8% (26/58) patients would consider marriage in future. Most patients (42/60) were worried about the smaller size of the phallus and lack of adequate semen, leading to apprehension before marriage. As much as 15 patients had jobs, 15 attended school, 3 attended colleges and 17 illiterate patients were dependent on their families.

CONCLUSIONS

Despite moral, social and economic support provided by the parents, children with DSD continue to have apprehensions in social adjustments.

Disorders of sex development expose transcriptional autonomy of genetic sex and androgen-programmed hormonal sex in human blood leukocytes

BACKGROUND

Gender appears to be determined by independent programs controlled by the sex-chromosomes and by androgen-dependent programming during embryonic development. To enable experimental dissection of these components in the human, we performed genome-wide profiling of the transcriptomes of peripheral blood mononuclear cells (PBMC) in patients with rare defined "disorders of sex development" (DSD, e.g., 46, XY-females due to defective androgen biosynthesis) compared to normal 46, XY-males and 46, XX-females.

RESULTS

A discrete set of transcripts was directly correlated with XY or XX genotypes in all individuals independent of male or female phenotype of the external genitalia. However, a significantly larger gene set in the PBMC only reflected the degree of external genital masculinization independent of the sex chromosomes and independent of concurrent post-natal sex steroid hormone levels. Consequently, the architecture of the transcriptional PBMC-"sexes" was either male, female or even "intersex" with a discordant alignment of the DSD individuals' genetic and hormonal sex signatures.

CONCLUSION

A significant fraction of gene expression differences between males and females in the human appears to have its roots in early embryogenesis and is not only caused by sex chromosomes but also by long-term sex-specific hormonal programming due to presence or absence of androgen during the time of external genital masculinization. Genetic sex and the androgen milieu during embryonic development might therefore independently modulate functional traits, phenotype and diseases associated with male or female gender as well as with DSD conditions.

Clinical evaluation study of the German network of disorders of sex development (DSD)/intersexuality: study design, description of the study population, and data quality

BACKGROUND

The German Network of Disorders of Sex Development (DSD)/Intersexuality carried out a large scale clinical evaluation study on quality of life, gender identity, treatment satisfaction, coping, and problems associated with diagnoses and therapies in individuals with disorders of sex development (DSD). DSD are a heterogeneous group of various genetic disorders of sex determination or sex differentiation, all of which are rare conditions. In about half of all cases the molecular genetic diagnosis is unknown and diagnosis rests on clinical features.

METHODS AND DESIGN

The multi-centre clinical evaluation study includes short-term follow-up in some and cross-sectional assessments in all age and diagnostic groups fitting the criteria of DSD. Recruitment was from January 2005 until December 2007 in whole Germany and, additionally, in 2007 in Austria and German-speaking Switzerland. The study consists of a psychosocial inquiry for children, adolescents and their parents, and adults with standardized instruments and the collection of DSD-specific medical data by the attending physician. The main goal was the description of clinical outcomes and the health-care situation of individuals with DSD using a broad generic definition of DSD including all conditions with a mismatch of chromosomal, gonadal and phenotypical sex. 439 children and adolescents, their parents and adults with DSD participated.

DISCUSSION

The clinical evaluation study represents the most comprehensive study in this clinical field. The paper discusses the study protocol, the data management and data quality as well as the classification used, and it describes the study population. Given the lack of large datasets in rare conditions such as DSD and often biased results from small scale clinical case series, the study aims to generate concrete hypotheses for evidence-based guidelines, which should be tested in further studies.