<p>Background: 46,XX testicular/ovotesticular disorders of sexual development (T/OT DSD) are infrequent congenital conditions characterized by the presence of functional ovarian and testicular or only testicular parenchyma. The aim of the study was to retrospectively describe clinical, hormonal, and genetic characteristics of 29 patients with 46,XX T/OT DSD (2000-2023), focusing on gonadal function, hormonal production, and long-term follow-up. Most patients (n = 25, 86.2%) presented with atypical genitalia that suggested DSD. Median age at first assessment was 0.38 years. Sex assignment was male in 21 patients without reports of discordant gender identity. Sex assignment was recommended before expert evaluation and without adequate studies in 64% of those patients with atypical genitalia (16/25). The median external masculinization score was 8 (range 4-12). During mini-puberty, LH, testosterone, AMH, and the LH/FSH ratio were above the female reference range and no different from the normal male reference range. Spontaneous puberty was observed in one female and 10 male-assigned subjects. Among the latter, pubertal virilization occurred with signs of hypergonadotropic hypogonadism and gynecomastia. Molecular studies identified the underlying mechanism in 7 patients: SRY gene was identified in two, WT1 gene variations were detected in three others, and 2 syndromic patients harbored complex chromosomal rearrangements. Our findings underscore the clinical and biochemical variability in 46,XX T/OT DSD. Expert evaluation and accurate diagnostic work-up are essential prior to sex assignment and to prevent misdiagnosis and inappropriate treatments. Mini-puberty was characterized by a masculinized pattern of gonadotropin secretion. The potential for functional male pubertal development should be taken into account when making sex assignment decisions. </p>.

46,XX testicular/ovotesticular differences/disorders of sexual development (TDSD/OTDSD) are rare in childhood and exhibit marked distinctions compared to those in adulthood. This study aimed to summarize the clinical characteristics and outcomes of 46,XX TDSD/OTDSD in childhood. The sexual development characteristics, hormone profiles, chromosomal analysis, fluorescence in situ hybridization analysis (FISH) sex-determining region Y (SRY) analysis (peripheral blood and tissues), molecular genetic etiology, gonadal pathology, risk of gonadal tumors, and assigned gender of 52 patients were collected and analyzed. The median age at initial presentation was 18 months, and external masculinization score(EMS) within the range of 3 < EMS ≤ 6 was more prevalent. There were no statistical differences in hormone levels [luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone (T)] between the different age groups. Among the 52 children, 4 showed positive SRY in peripheral blood, whereas none of the 8 children exhibited positive SRY in tissue samples. A total of 29 children underwent whole exome sequencing (WES) and copy number variant (CNV) analysis, but no genetic variants were identified. A total of 47 children underwent gonadal biopsy and showed no evidence of tumors. However, immunohistochemical analysis revealed that 2 of 16 children were OCT3/4 positive. The most frequent type of gonadal pathology (17/47) was bilateral seminiferous tubules. After the assessment, gender assignment was revised in six cases: five individuals originally assigned as female at birth were reassigned as male, while one individual assigned as male was changed to female. In seven cases, the gender of rearing remained undetermined pending further longitudinal psychosocial assessment. Among the female-reared cohort, three children were more than 11 years old. As a result of undergoing bilateral gonadectomy at an early age, the patients were unable to spontaneously enter puberty. However, given their short stature, they are receiving growth hormone (GH) treatment and have not yet received sufficient sex hormone replacement therapy (HRT). Among the male-reared cohort, seven children had entered puberty. The average age at puberty onset was 12 ± 0.87 years, the average testicular volume was 5.14 ± 1.57 mL, the mean basal LH level was 6.44 ± 4.19 IU/L, the mean basal FSH level was 13.18 ± 10.22 IU/L, and the mean basal T was 3.40 ± 1.63 nmol/L. Compared to adults, children with 46,XX testicular/ovotesticular DSD were very different. SRY-negative children were predominant and tended to have more severe external genital abnormalities during childhood. Peripheral blood or tissue SRY mosaicism was not a prevalent cause and the intricate genetic pathways behind these cases were unknown. There were no statistical differences in hormone levels (LH, FSH, and T) between the different age groups. The assigned gender is mainly male, and the incidence of gonadal tumor risk markers was modest. During adolescence, their testosterone levels could normalize despite elevated FSH and LH levels.

Duplications occurring upstream of the SOX9 gene have been identified in a limited subset of patients with 46,XX testicular/ovotesticular differences/disorders of sex development (DSD). However, comprehensive understanding regarding their clinical presentation and diagnosis is limited. To gain further insight into the diagnosis of a large cohort of 46,XX individuals with duplications upstream of SOX9. We retrospectively analyzed data of 46,XX/SRY-negative individuals with SOX9 upstream duplications. Clinical data were recorded, and genetic etiologies were investigated using karyotyping, fluorescence in situ hybridization (FISH) for SRY analysis, microarray analysis, multiplex ligation-dependent probe amplification (MLPA) and next-generation sequencing panels including whole genome sequencing. We analyzed 12 individuals with 46,XX karyotype who had heterozygous duplications upstream of SOX9, ranging from 107 to 941 kb. Ages at diagnosis ranged from 0.1 to 55 years. Seven (58%) had testicular/ovotesticular DSD, while 5 (41%) were asymptomatic carriers detected through family screening. There was no significant correlation between duplication size and genital/gonadal phenotype. The duplication was inherited from the father (n = 3) or an asymptomatic mother (n = 2). In one family, a duplication missed by the 300K microarray was detected by MLPA and confirmed with 750K microarray. 46,XX individuals with SOX9 upstream duplications may exhibit no symptoms, but thorough family screening is crucial due to the potential inheritance and testicular/ovotesticular DSD risk in subsequent generations. We emphasize the effectiveness of high-resolution microarray analysis (>500K) as the primary diagnostic tool for 46,XX/SRY-negative testicular/ovotesticular DSD individuals, enabling thorough genome-wide assessment of copy number variations and detecting small alterations.

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. 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. 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. Nonsyndromic 46,XX testicular disorders/differences of sex development (DSD) are characterized by: the presence of a 46,XX karyotype; external genitalia ranging from typical male to ambiguous; two testicles; azoospermia; absence of müllerian structures; and absence of other syndromic features, such as congenital anomalies outside of the genitourinary system, learning disorders / cognitive impairment, or behavioral issues. Approximately 85% of individuals with nonsyndromic 46,XX testicular DSD present after puberty with normal pubic hair and normal penile size but small testes, gynecomastia, and sterility resulting from azoospermia. Approximately 15% of individuals with nonsyndromic 46,XX testicular DSD present at birth with ambiguous genitalia. Gender role and gender identity are reported as male. If untreated, males with 46,XX testicular DSD experience the consequences of testosterone deficiency. Diagnosis of nonsyndromic 46,XX testicular DSD is based on the combination of clinical findings, endocrine testing, and cytogenetic testing. Endocrine studies usually show hypergonadotropic hypogonadism secondary to testicular failure. Cytogenetic studies at the 550-band level demonstrate a 46,XX karyotype. SRY, the gene that encodes the sex-determining region Y protein, is the principal gene known to be associated with 46,XX testicular DSD. Approximately 80% of individuals with nonsyndromic 46,XX testicular DSD are SRY positive, as shown by use of FISH or chromosomal microarray. Other causes in SRY-negative individuals include small copy number variants (CNVs) in or around SOX3 or SOX9 and specific heterozygous pathogenic variants in NR5A1 or WT1. Treatment of manifestations: Similar to that for other causes of testosterone deficiency. After age 14 years, low-dose testosterone therapy is initiated and gradually increased to reach adult levels. In affected individuals with short stature who are eligible for growth hormone therapy, testosterone therapy is either delayed or given at lower doses initially in order to maximize growth potential. Reduction mammoplasty may be considered if gynecomastia remains an issue following testosterone replacement therapy. Standard treatment for osteopenia, hypospadias, and cryptorchidism. Providers are encouraged to anticipate the need for further psychological support. Surveillance: Measurement of length/height at each visit. Assessment of mood, libido, energy, erectile function, acne, breast tenderness, and presence or progression of gynecomastia at each visit in adolescence and adulthood. For those on testosterone replacement therapy: measurement of serum testosterone levels every three months (just prior to the next injection) until testosterone dose is optimized; then annual measurement of serum testosterone levels, lipid profile, and liver function tests. Measurement of hematocrit at three, six, and 12 months after initiation of testosterone therapy, then annually thereafter. Digital rectal examination and measurement of serum prostate-specific antigen at three, six, and 12 months after initiation of testosterone therapy in adults, then annually thereafter. Dual-energy x-ray absorptiometry scan every three to five years after puberty or annually, if osteopenia has been identified. Agents/circumstances to avoid: Contraindications to testosterone replacement therapy include prostate cancer (known or suspected) and breast cancer; oral androgens such as methyltestosterone and fluoxymesterone should not be given because of liver toxicity. The mode of inheritance and recurrence risk to sibs of a proband with a nonsyndromic 46,XX testicular DSD depend on the molecular diagnosis in the proband and the genetic status of the parents. SRY-positive 46,XX testicular DSD is generally not inherited because it results from de novo abnormal interchange between the Y chromosome and the X chromosome, resulting in the presence of SRY on the X chromosome and infertility. In the rare cases when SRY is translocated to another chromosome or when fertility is preserved, sex-limited autosomal dominant inheritance is observed. Pathogenic variants in NR5A1 are inherited in an autosomal dominant fashion, with reduced penetrance and variable expressivity. If a fertile parent is heterozygous, they will pass the variant to 50% of their offspring; offspring who are XX are at risk for testicular or ovotesticular DSD. To date, all known individuals with CNVs in or around SOX3 whose parents have undergone molecular genetic testing have the disorder as a result of a de novo pathogenic variant. In this scenario, the risk to sibs is low. Autosomal dominant inheritance has been documented for familial cases thought to be caused by CNVs in or around SOX9. However, only those with a 46,XX karyotype will be affected. To date, all known individuals with a pathogenic WT1 variant that causes nonsyndromic 46,XX testicular DSD whose parents have undergone molecular genetic testing have the disorder as a result of a de novo pathogenic variant. In this scenario, the risk to sibs is low.

Prenatal-onset androgen excess leads to abnormal sexual development in 46,XX individuals. This androgen excess can be caused endogenously by the adrenals or gonads or by exposure to exogenous androgens. The most common cause of 46,XX disorders/differences in sex development (DSD) is congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency, comprising >90% of 46,XX DSD cases. Deficiencies of 11β-hydroxylase, 3β-hydroxysteroid dehydrogenase, and P450-oxidoreductase (POR) are rare types of CAH, resulting in 46,XX DSD. In all CAH forms, patients have normal ovarian development. The molecular genetic causes of 46,XX DSD, besides CAH, are uncommon. These etiologies include primary glucocorticoid resistance (PGCR) and aromatase deficiency with normal ovarian development. Additionally, 46,XX gonads can differentiate into testes, causing 46,XX testicular (T) DSD or a coexistence of ovarian and testicular tissue, defined as 46,XX ovotesticular (OT)-DSD. PGCR is caused by inactivating variants in NR3C1, resulting in glucocorticoid insensitivity and the signs of mineralocorticoid and androgen excess. Pathogenic variants in the CYP19A1 gene lead to aromatase deficiency, causing androgen excess. Many genes are involved in the mechanisms of gonadal development, and genes associated with 46,XX T/OT-DSD include translocations of the SRY; copy number variants in NR2F2, NR0B1, SOX3, SOX9, SOX10, and FGF9, and sequence variants in NR5A1, NR2F2, RSPO1, SOX9, WNT2B, WNT4, and WT1. Progress in cytogenetic and molecular genetic techniques has significantly improved our understanding of the etiology of non-CAH 46,XX DSD. Nonetheless, uncertainties about gonadal function and gender outcomes may make the management of these conditions challenging. This review explores the intricate landscape of diagnosing and managing these conditions, shedding light on the unique aspects that distinguish them from other types of DSD.