Up-regulation of SOX9 in human sex-determining region on the Y chromosome (SRY)-negative XX males

Molecular cytogenetic analysis and genetic counseling: a case report of eight 46,XX males and a literature review

Background

46,XX male syndrome is a rare disorder that usually causes infertility. This study was established to identify the genetic causes of this condition in a series of 46,XX males through the combined application of cytogenetic and molecular genetic techniques.

Case presentation

We identified eight azoospermic 46,XX males who underwent infertility-related consultations at our center. They all presented normal male phenotypes. In seven of the eight 46,XX males (87.5%), translocation of the SRY gene to the terminal short arm of the X chromosome was clearly involved in their condition, which illustrated that this translocation is the main mechanism of 46,XX sex reversal, in line with previous reports. However, one patient presented a homozygous DAX1 mutation (c.498G > A, p.R166R), which was not previously reported in SRY-negative XX males.

Conclusions

We proposed that this synonymous DAX1 mutation in case 8 might not be associated with the activation of the male sex-determining pathway, and the male phenotype in this case might be regulated by some unidentified genetic or environmental factors. Hence, the detection of genetic variations associated with sex reversal in critical sex-determining genes should be recommended for SRY-negative XX males. Only after comprehensive cytogenetic and molecular genetic analyses can genetic counseling be offered to 46,XX males.

Female-to-male sex reversal associated with unique Xp21.2 deletion disrupting genomic regulatory architecture of the dosage-sensitive sex reversal region

BACKGROUND

The XX male disorder of sex development (DSD) is a rare condition that is most commonly associated with the presence of the SRY gene on one of the X chromosomes due to unequal crossing-over between sex chromosomes during spermatogenesis. However, in about 20% of the XX male individuals, SRY is missing, although these persons have at least some testis differentiation. The genetic basis of genital ambiguity and the mechanisms triggering testis development in such patients remain unknown.

METHODS

The proband with 46,XX SRY-negative testicular DSD was screened for point mutations by whole exome sequencing and CNVs using a high-resolution DSD gene-targeted and whole genome array comparative genomic hybridisation. The identified Xp21.2 genomic alteration was further characterised by direct sequencing of the breakpoint junctions and bioinformatics analysis.

RESULTS

A unique, 80 kb microdeletion removing the regulatory sequences and the NR0B1 gene was detected by microarray analysis. This deletion disturbs the human-specific genomic architecture of the Xp21.2 dosage-sensitive sex (DSS) reversal region in the XX patient with male-appearing ambiguous genitalia and ovotestis.

CONCLUSIONS

Duplication of the DSS region containing the MAGEB and NR0B1 genes has been implicated in testis repression and sex reversal. Identification of this microdeletion highlights the importance of genomic integrity in the regulation and interaction of sex determining genes during gonadal development.

46 XX karyotype during male fertility evaluation; case series and literature review

Forty-six XX disorder of sex development is an uncommon medical condition observed at times during the evaluation of a man's fertility. The following is a case series and literature review of phenotypically normal men diagnosed with this karyotype. Our goal is to comprehend the patients’ clinical presentation as well as their laboratory results aiming to explore options available for their management. A formal literature review through PubMed and MEDLINE databases was performed using “46 XX man” as a word search. A total of 55 patients, including those conveyed in this article were diagnosed with a 46 XX karyotype during their fertility evaluation. The patients’ mean age ± s.d. was 34 ± 10 years and their mean height ± s.d. was 166 ± 6.5 cm. Overall, they presented with hypergonadotropic hypogonadism. Sexual dysfunction, reduced hair distribution, and gynecomastia were reported in 20% (4/20), 25.8% (8/31), and 42% (13/31) of the patients, respectively. The SRY gene was detected in 36 (83.7%) and was absent in the remaining seven (16.3%) patients. We found that a multidisciplinary approach to management is preferred in 46 XX patients. Screening for remnants of the mullerian ducts and for malignant transformation in dysgenetic gonads is imperative. Hypogonadism should be addressed, while fertility options are in vitro fertilization with donor sperm or adoption.

Molecular mechanisms associated with 46,XX disorders of sex development

In the female gonad, distinct signalling pathways activate ovarian differentiation while repressing the formation of testes. Human disorders of sex development (DSDs), such as 46,XX DSDs, can arise when this signalling is aberrant. Here we review the current understanding of the genetic mechanisms that control gonadal development, with particular emphasis on those that drive or inhibit ovarian differentiation. We discuss how disruption to these molecular pathways can lead to 46,XX disorders of ovarian development. Finally, we look at recently characterized novel genes and pathways that contribute and speculate how advances in technology will aid in further characterization of normal and disrupted human ovarian development.

Cryopreservation of testicular tissue before long-term testicular cell culture does not alter in vitro cell dynamics

OBJECTIVE

To assess whether testicular cell dynamics are altered during long-term culture after testicular tissue cryopreservation.

DESIGN

Experimental basic science study.

SETTING

Reproductive biology laboratory.

PATIENT(S)

Testicular tissue with normal spermatogenesis was obtained from six donors.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Detection and comparison of testicular cells from fresh and frozen tissues during long-term culture.

RESULT(S)

Human testicular cells derived from fresh (n = 3) and cryopreserved (n = 3) tissues were cultured for 2 months and analyzed with quantitative reverse-transcription polymerase chain reaction and immunofluorescence. Spermatogonia including spermatogonial stem cells (SSCs) were reliably detected by combining VASA, a germ cell marker, with UCHL1, a marker expressed by spermatogonia. The established markers STAR, ACTA2, and SOX9 were used to analyze the presence of Leydig cells, peritubular myoid cells, and Sertoli cells, respectively. No obvious differences were found between the cultures initiated from fresh or cryopreserved tissues. Single or small groups of SSCs (VASA(+)/UCHL1(+)) were detected in considerable amounts up to 1 month of culture, but infrequently after 2 months. SSCs were found attached to the feeder monolayer, which expressed markers for Sertoli cells, Leydig cells, and peritubular myoid cells. In addition, VASA(-)/UCHL1(+) cells, most likely originating from the interstitium, also contributed to this monolayer. Apart from Sertoli cells, all somatic cell types could be detected throughout the culture period.

CONCLUSION(S)

Testicular tissue can be cryopreserved before long-term culture without modifying its outcome, which encourages implementation of testicular tissue banking for fertility preservation. However, because of the limited numbers of SSCs available after 2 months, further exploration and optimization of the culture system is needed.

The battle of the sexes for stroke therapy: female- versus male-derived stem cells

Cell therapy is a major discipline of regenerative medicine that has been continually growing over the last two decades. The aging of the population necessitates discovery of therapeutic innovations to combat debilitating disorders, such as stroke. Menstrual blood and Sertoli cells are two gender-specific sources of viable transplantable cells for stroke therapy. The use of autologous cells for the subacute phase of stroke offers practical clinical application. Menstrual blood cells are readily available, display proliferative capacity, pluripotency and angiogenic features, and, following transplantation in stroke models, have the ability to migrate to the infarct site, regulate the inflammatory response, secrete neurotrophic factors, and have the possibility to differentiate into neural lineage. Similarly, the testis-derived Sertoli cells secrete many growth and trophic factors, are highly immunosuppressive, and exert neuroprotective effects in animal models of neurological disorders. We highlight the practicality of experimental and clinical application of menstrual blood cells and Sertoli cells to treat stroke, from cell isolation and cryopreservation to administration.

Elucidation of distinctive genomic DNA structures in patients with 46,XX testicular disorders of sex development using genome wide analyses

PURPOSE

Although several genes, including the SRY gene, are involved in testicular differentiation, the entire mechanism of this differentiation remains unclear. We performed genome wide analysis in patients with 46,XX testicular disorders of sex development to comprehensively elucidate the mechanisms of testicular differentiation.

MATERIALS AND METHODS

Whole genomic DNA was extracted from the peripheral blood of 4 patients with 46,XX testicular disorders of sex development who were SRY negative. Genomic DNA was hybridized to a GeneChip® human mapping 250K array set. Compared to normal female data, we detected common loss of heterozygosity and copy number variation regions in 4 patients using Genotyping Console™ software.

RESULTS

Loss of heterozygosity was detected in 19 regions of 11 chromosomes. A total of 27 genes or nearby genomic areas were included in the applicable regions. Copy number loss was recognized in 13 regions of 10 chromosomes, and these regions included 55 genes. Copy number gain was detected in 6 regions of 4 chromosomes, which included the upstream region of the SOX3 gene.

CONCLUSIONS

The regions with loss of heterozygosity did not contain genes associated with testicular differentiation. However, the upstream area of the SOX3 gene, which is located in Xq27.1, was included in the region of copy number gain. These results suggest that high expression of the SOX3 gene led to testicular differentiation despite SRY gene loss. As this applicable area is not within a coding region, genome wide analyses were valuable for detecting the novel regions associated with testicular differentiation.

Gene expression profile during testicular development in patients with SRY-negative 46,XX testicular disorder of sex development

OBJECTIVE

To elucidate alternative pathways in testicular development, we attempted to clarify the genetic characteristics of SRY-negative XX testes.

MATERIALS AND METHODS

We previously reported 5 cases of SRY-negative 46,XX testicular disorders of sex development and demonstrated that coordinated expression of genes such as SOX9, SOX3, and DAX1 was associated with testicular development. We performed a case-control study between the aforementioned boy with 46,XX testicular disorders of sex development and an age-matched patient with hydrocele testis (46,XY). During their consecutive surgeries, testicular biopsy specimens were obtained. Genes with differential expression compared with XY testis were identified using polymerase chain reaction (PCR)-based subtractive hybridization and sequencing. For validation of differential gene expression, real-time RT-PCR was performed using gene-specific primers. The distribution of candidate proteins in the testicular tissue was clarified by immunohistochemistry in human and rodent specimens. Moreover, in vitro inhibitory assays were performed.

RESULTS

We identified 13 upregulated and 7 downregulated genes in XX testis. Among the candidate genes, we focused on ROCK1 (Rho-associated, coiled-coil protein kinase 1) in the upregulated gene group, because high expression in XX testis was validated by real-time RT-PCR. ROCK1 protein was detected in germ cells, Leydig cells, and Sertoli cells by immunohistochemistry. Moreover, the addition of specific ROCK1 inhibitor to Sertoli cells decreased SOX9 gene expression.

CONCLUSION

On the basis of in vitro inhibitory assay, it is suggested that ROCK1 phosphorylates and activates SOX9 in Sertoli cells. Testes formation might be initiated by an alternative signaling pathway attributed to ROCK1, not SRY, activation in XX testes.

All males do not have 46 xy karyotype: A rare case report

The sex of an embryo is determined by genetic sex due to presence or absence of Y chromosome, but it may not be true in all. We hereby report an interesting case of a phenotypic male carrying a female karyotype (46 XX). A 26-year-old male presented with bilateral gynecomastia, poor development of secondary sexual characters and azospermia. On evaluation patient had hypergonadotrophic hypogonadism and chromosomal analysis revealed 46 XX karyotype. The ultrasound revealed no Mullerian structures. Fluorescent in situ hybridization (FISH) showed sex determining region of Y chromosome (SRY) gene locus on X chromosome.

A case report of an incidental finding of a 46,XX, SRY-negative male with masculine phenotype during standard fertility workup with review of the literature and proposed immediate and long-term management guidance

OBJECTIVE

To describe and explore the current literature on the rare genetic condition of 46,XX SRY-negative males. In addition, we propose comprehensive clinical guidelines in the management of this condition to aid fertility clinicians in their management of affected individuals.

DESIGN

Case report with expert consensus-derived clinical management guidance.

SETTING

Fertility outpatient clinic at a tertiary referral center.

PATIENT(S)

A 40-year-old male found to have 46,XX disorder of sex development (DSD) on routine fertility screening.

INTERVENTION(S)

A review of the literature, expert consultation, and formulation of comprehensive clinical guidance.

MAIN OUTCOME MEASURE(S)

We report an interesting and rare case of a phenotypical male with the karyotype 46,XX DSD without an SRY region. There is limited literature exploring this condition, and its etiology remains poorly understood. There is currently no clinical guidance available for fertility clinicians to follow when treating this condition.

RESULT(S)

A male phenotype with a 46 karyotype without the sex-defining region of the Y chromosome.

CONCLUSION(S)

A multidisciplinary approach should be adopted in the management of 46,XX individuals. All patients with azoospermia must be karyotyped. Sperm donation remains the only fertility treatment available. The 46,XX patients need lifelong followup led by an endocrinologist with regular imaging of the gonads, bone density measurements, baseline blood tests, and T supplementation. Psychological support is a key part of a holistic approach.

Duplication of SOX9 is not a common cause of 46,XX testicular or 46,XX ovotesticular DSD

BACKGROUND

Translocation of the SRY gene to the paternal X chromosome is the explanation for testis development in the majority of subjects with 46,XX testicular disorder of sexual development (DSD). However, nearly all subjects with 46,XX ovotesticular DSD and up to one third of subjects with 46,XX testicular DSD lack SRY. SRY-independent expression of SOX9 has been implicated in the etiology of testis development in some individuals.

METHODS

We amplified microsatellite markers in the region of SOX9 from a cohort of 30 subjects with either 46,XX testicular or 46,XX ovotesticular DSD to detect SOX9 duplications.

RESULTS

Duplication of the SOX9 region in 17q was not detected in any subject.

CONCLUSION

Duplication in the region of 17q that contains SOX9 is not a common cause of testis development in subjects with SRY-negative 46,XX testicular or ovotesticular DSD.

Clinical features and testicular morphology in patients with Kallmann syndrome

Kallmann syndrome (KS) is a genetic disorder characterized by the simultaneous occurrence of idiopathic hypogonadotropic hypogonadism (IHH) and anosmia. Here, we present 3 cases of KS with detailed description. In Case 1, testicular morphology was examined by testicular biopsy, and Leydig cells were examined by immunohistochemistry using antibodies against Ad4BP/SF1. Contrary to our predictions, the present study revealed the presence of Leydig cells in the testis. Testicular morphology in the patients with KS is more varied than expected, and further investigation is required to elucidate hormonal effects on normal testicular development.

Pure non-gestational ovarian choriocarcinoma in a 45,XO/46,XX SRY-negative true hermaphrodite

Non-gestational ovarian choriocarcinoma (NGCO) is an extremely rare malignant tumor with a poor prognosis and is difficult to distinguish from gestational choriocarcinoma. True hermaphrodite (TH) is genetically a heterogenous condition causing ovarian and testicular tissue development in the same individual. We report here the first case of pure NGCO in the right ovotestis of a 23-year-old 45,XO/46X,X sex-determining region Y chromosome (SRY)-negative TH. The diagnosis of non-gestational origin was confirmed by testing five short tandem repeats (STR). The patient responded well to radical surgery with bleomycin, etoposide, cisplatin (BEP) regimen. We also hypothesize that some mutations of an X-linked or autosomal gene lead to testicular determination in SRY-negative TH patients.

46,XX male - testicular disorder of sexual differentiation (DSD): hormonal, molecular and cytogenetic studies

The XX male syndrome - Testicular Disorder of Sexual Differentiation (DSD) is a rare condition characterized by a spectrum of clinical presentations, ranging from ambiguous to normal male genitalia. We report hormonal, molecular and cytogenetic evaluations of a boy presenting with this syndrome. Examination of the genitalia at age of 16 months, showed: penis of 3.5 cm, proximal hypospadia and scrotal testes. Pelvic ultrasound did not demonstrate Mullerian duct structures. Karyotype was 46,XX. Gonadotrophin stimulation test yielded insufficient testosterone production. Gonadal biopsy showed seminiferous tubules without evidence of Leydig cells. Molecular studies revealed that SRY and TSPY genes and also DYZ3 sequences were absent. In addition, the lack of deletions or duplications of SOX9, NR5A1, WNT4 and NROB1 regions was verified. The infant was heterozygous for all microsatellites at the 9p region, including DMRT1 gene, investigated. Only 10% of the patients are SRY-negative and usually they have ambiguous genitalia, as the aforementioned patient. The incomplete masculinization suggests gain of function mutation in one or more genes downstream to SRY gene.

46, XX SRY-positive male syndrome presenting with primary hypogonadism in the setting of scleroderma

OBJECTIVE

To describe a case of SRY gene translocation in a man with scleroderma presenting with primary hypogonadism.

METHODS

We present the clinical, physical, laboratory, and pathologic findings of the study patient and discuss the cytogenetic analysis and the cause of the sexual dysfunction. Relevant literature is reviewed.

RESULTS

A 35-year-old man with a recent diagnosis of diffuse cutaneous sclerosis was referred by his rheumatologist because of a low testosterone level. His medical history was notable for right cryptorchidism corrected after birth. He had no history of sexual activity, but reported normal erectile function before his current presentation. Physical examination findings were remarkable for a height of 157.5 cm; weight of 72.7 kg; extensive, diffuse thickening of the skin; mild gynecomastia; little axillary and pubic hair; and soft testes (1-2 mL bilaterally). Initial laboratory testing revealed the following values: follicle-stimulating hormone, 22.1 mIU/mL (reference range, 1.4-18.1 mIU/mL); luteinizing hormone, 19.7 mIU/mL (reference range, 1.5-9.3 mIU/mL); total testosterone, 25 ng/dL (reference range, 241-827 ng/dL); and free direct testosterone, 0.8 pg/mL (reference range, 8.7-25.1 pg/mL). Laboratory test results were consistent with primary hypogonadism. A urologist performed testicular biopsy, which showed severe testicular atrophy with absent spermatogenesis. Primary hypogonadism due to Klinefelter syndrome or testicular fibrosis secondary to scleroderma was suspected. Karyotype analysis showed a 46, XX karyotype, and fluorescence in situ hybridization was consistent with a 46, XX, Xp22.3(SRY+) gene translocation. After a normal prostate-specific antigen level was documented, testosterone replacement therapy was initiated, and he was referred for genetic counseling.

CONCLUSIONS

The 46, XX SRY-positive male syndrome is rare. Adult diagnosis can be challenging because of normal sexual development. Scleroderma, which rarely can occur in Klinefelter-type syndromes, further complicated the diagnosis in this case.

Identification of new susceptibility regions for X;Y translocations in patients with testicular disorder of sex development

Testicular disorder of sex development in the presence of a 46,XX karyotype is a rare condition. In most instances, it is caused by an X;Y translocation in the paternal gametes, causing SRY to be transferred on the X chromosome. An abnormal recombination event between homologous genes PRKX and PRKY is implicated in approximately one third of the cases. In this study, we report the characterization by fluorescence in situ hybridization of four patients with a 46,X,der(X)t(X;Y) constitution: two monozygotic adult twins, one adult male and a young boy. Molecular cytogenetic analyses using BAC clones specific to the X and Y chromosomes revealed that the translocation is not mediated by an abnormal PRKX-PRKY recombination event in any of our patients. On the other hand, the twins and the adult male have similar breakpoints, having almost the entire short arm of the Y chromosome translocated on their der(X). On their der(X) chromosome, breakpoints are located close to PRKX, in an interval of less than 200 kb. As for the young boy, his breakpoints are located approximately 300 kb proximal to SRY, in Yp11.31, and at the beginning of the pseudoautosomal region in Xp22.33. Our data suggest that some regions are prone to breakage on the sex chromosomes and that these regions represent possible hot spots for X;Y translocations that are not mediated by abnormal recombination.

Characterization and functionality of proliferative human Sertoli cells

It has long been thought that mammalian Sertoli cells are terminally differentiated and nondividing postpuberty. For most previous in vitro studies immature rodent testes have been the source of Sertoli cells and these have shown little proliferative ability when cultured. We have isolated and characterized Sertoli cells from human cadaveric testes from seven donors ranging from 12 to 36 years of age. The cells proliferated readily in vitro under the optimized conditions used with a doubling time of approximately 4 days. Nuclear 5-ethynyl-2'-deoxyuridine (EdU) incorporation confirmed that dividing cells represented the majority of the population. Classical Sertoli cell ultrastructural features, lipid droplet accumulation, and immunoexpression of GATA-4, Sox9, and the FSH receptor (FSHr) were observed by electron and fluorescence microscopy, respectively. Flow cytometry revealed the expression of GATA-4 and Sox9 by more than 99% of the cells, and abundant expression of a number of markers indicative of multipotent mesenchymal cells. Low detection of endogenous alkaline phosphatase activity after passaging showed that few peritubular myoid cells were present. GATA-4 and SOX9 expression were confirmed by reverse transcription polymerase chain reaction (RT-PCR), along with expression of stem cell factor (SCF), glial cell line-derived neurotrophic factor (GDNF), and bone morphogenic protein 4 (BMP4). Tight junctions were formed by Sertoli cells plated on transwell inserts coated with fibronectin as revealed by increased transepithelial electrical resistance (TER) and polarized secretion of the immunoregulatory protein, galectin-1. These primary Sertoli cell populations could be expanded dramatically in vitro and could be cryopreserved. The results show that functional human Sertoli cells can be propagated in vitro from testicular cells isolated from adult testis. The proliferative human Sertoli cells should have important applications in studying infertility, reproductive toxicology, testicular cancer, and spermatogenesis, and due to their unique biological properties potentially could be useful in cell therapy.

Disorders of Sexual Differentiation

The term, disorders of sexual differentiation, broadly represents a disjunction between genotype and phenotype. Phenotype in turn can refer to external or internal genital development. Disorders of sexual differentiation are determined at conception insofar as (1) the abnormal genotype is the aberrant genetic product of fertilization at the chromosomal level or (2) the abnormal phenotype results from postfertilization errors in function at the gene level, somewhere along the pathway of transcription and translation. In either event, the error is genetic, whether or not sporadic or inherited, even if the pathways have yet to be fully elucidated for a given disorder.

The mechanism of ascorbic acid-induced differentiation of ATDC5 chondrogenic cells

The ATDC5 cell line exhibits a multistep process of chondrogenic differentiation analogous to that observed during endochondral bone formation. Previous investigators have induced ATDC5 cells to differentiate by exposing them to insulin at high concentrations. We have observed spontaneous differentiation of ATDC5 cells maintained in ascorbic acid-containing alpha-MEM. A comparison of the differentiation events in response to high-dose insulin vs. ascorbic acid showed similar expression patterns of key genes, including collagen II, Runx2, Sox9, Indian hedgehog, and collagen X. We took advantage of the action of ascorbic acid to examine signaling events associated with differentiation. In contrast to high-dose insulin, which downregulates both IGF-I and insulin receptors, there were only minimal changes in the abundance of these receptors during ascorbic acid-induced differentiation. Furthermore, ascorbic acid exposure was associated with ERK activation, and ERK inhibition attenuated ascorbic acid-induced differentiation. This was in contrast to the inhibitory effect of ERK activation during IGF-I-induced differentiation. Inhibition of collagen formation with a proline analog markedly attenuated the differentiating effect of ascorbic acid on ATDC5 cells. When plates were conditioned with ATDC5 cells exposed to ascorbic acid, ATDC5 cells were able to differentiate in the absence of ascorbic acid. Our results indicate that matrix formation early in the differentiation process is essential for ascorbic acid-induced ATDC5 differentiation. We conclude that ascorbic acid can promote the differentiation of ATDC5 cells by promoting the formation of collagenous matrix and that matrix formation mediates activation of the ERK signaling pathway, which promotes the differentiation program.

Genetic pathway of external genitalia formation and molecular etiology of hypospadias

Hypospadias is one of the most common congenital disorders in males. Impaired fetal androgen action interferes with masculinization, including external genitalia formation, and can result in this anomaly; however, the molecular etiology remains unknown. Recent molecular approaches, including gene-targeting approaches in mice and single nucleotide polymorphisms analyses in humans, might provide an opportunity to identify the causative and risk factors of this anomaly. Several genes, such as sonic hedgehog, fibroblast growth factors, bone morphogenetic proteins, homeobox genes, and the Wnt family regulate external genitalia formation. Mastermind-like domain containing 1/chromosome X open reading frame 6 mutation and activating transcription factor 3 variants have been shown to be associated with the incidence of isolated hypospadias. In addition, this anomaly may be associated with a specific haplotype of the gene for estrogen receptor alpha, which mediates the estrogenic effects of environmental endocrine disruptors, and the effects of these disruptors on external genitalia formation might depend on individual genetic susceptibility. These molecular studies will refine our knowledge of the genetic mechanism involved in external genitalia formation, and lead to new strategies for the clinical management of hypospadias.

Epigenetic abnormality of SRY gene in the adult XY female with pericentric inversion of the Y chromosome

In normal ontogenetic development, the expression of the sex-determining region of the Y chromosome (SRY) gene, involved in the first step of male sex differentiation, is spatiotemporally regulated in an elaborate fashion. SRY is expressed in germ cells and Sertoli cells in adult testes. However, only few reports have focused on the expressions of SRY and the other sex-determining genes in both the classical organ developing through these genes (gonad) and the peripheral tissue (skin) of adult XY females. In this study, we examined the gonadal tissue and fibroblasts of a 17-year-old woman suspected of having disorders of sexual differentiation by cytogenetic, histological, and molecular analyses. The patient was found to have the 46,X,inv(Y)(p11.2q11.2) karyotype and streak gonads with abnormally prolonged SRY expression. The sex-determining gene expressions in the patient-derived fibroblasts were significantly changed relative to those from a normal male. Further, the acetylated histone H3 levels in the SRY region were significantly high relative to those of the normal male. As SRY is epistatic in the sex-determination pathway, the prolonged SRY expression possibly induced a destabilizing effect on the expressions of the downstream sex-determining genes. Collectively, alterations in the sex-determining gene expressions persisted in association with disorders of sexual differentiation not only in the streak gonads but also in the skin of the patient. The findings suggest that correct regulation of SRY expression is crucial for normal male sex differentiation, even if SRY is translated normally.

Severe XIST hypomethylation clearly distinguishes (SRY+) 46,XX-maleness from Klinefelter syndrome

OBJECTIVE

46,XX-maleness affects 1 in 20 000 live male newborns resulting in infertility and hypergonadotrophic hypogonadism. Although the phenotypes of XX-males have been well described, the molecular nature of the X chromosomes remains elusive. We assessed the X inactivation status by DNA methylation analysis of four informative loci and compared those to Klinefelter syndrome (KS) and Turner syndrome.

DESIGN AND METHODS

Patient cohort consisted of ten sex-determining region of the Y (SRY+) XX-males, two (SRY-) XX-males, ten 47,XXY Klinefelter men, six 45,X Turner females and ten male and female control individuals each. Methylation analysis was carried out by bisulphite sequencing of DNA from peripheral blood lymphocytes analysing X-inactive-specific transcript (XIST), phosphoglycerate kinase 1 (PGK1), ferritin, heavy peptide-like 17 (FTHL17) and short stature homeobox (SHOX).

RESULTS

XIST methylation was 18% in (SRY+) XX-males, and thus they were severely hypomethylated compared to (SRY-) XX-males (48%; P<0.01), Klinefelter men (44%; P<0.01) and female controls (47%; P<0.01). Turner females and male controls displayed a high degree of XIST methylation of 98 and 94% respectively. Methylation of PGK1, undergoing X inactivation, was not significantly reduced in (SRY+) XX-males compared to female controls in spite of severe XIST hypomethylation (51 vs 69%; P>0.05). FTHL17, escaping X inactivation, but undergoing cell-type-specific inactivation was similarly methylated in XX-males (89%), KS patients (87%) and female controls (90%). SHOX, an X inactivation escapee located in the pseudoautosomal region, displays similarly low degrees of methylation for XX-males (7%), KS patients (7%) and female controls (9%).

CONCLUSIONS

XIST hypomethylation clearly distinguishes (SRY+) XX-males from Klinefelter men. It does not, however, impair appropriate epigenetic regulation of representative X-linked loci.