A possible common origin of "Y-negative" human XX males and XX true hermaphrodites

Exploring uncharted territory: A case report on de la Chapelle syndrome presenting as male subfertility

INTRODUCTION

De la Chapelle Syndrome, also known as 46 XX disorders, is a genetic condition that affects sexual development and presents challenges, in physical, hormonal, and genetic aspects.

CASE PRESENTATION

This case study explores a 42-year man with de la Chapelle Syndrome who experienced primary subfertility for eight years. The patient demonstrated delayed development of secondary sexual characteristics, shrinking testes and sparse hair distribution. A team comprising fertility specialists, uro surgeons, endocrinologists and genetic counselors collaborated to develop an approach. Based on the patients 46 XX karyotype without sex-determining region Y gene mutation assisted reproduction using donor sperm was chosen as the option. The report delves into the genetics of both sex-determining region Y gene positive and sex-determining region Y gene negative cases while emphasizing the significance of conducting thorough evaluations for issues related to sexual differentiation.

DISCUSSION

Management strategies encompass an approach tailored to factors such as age, fertility desires and level of virilization exhibited by the patient. Surgical interventions, hormone treatments and psychological support all play roles in the management. Limited fertility treatment options are available for cases involving XX syndrome with testes such as intrauterine insemination using donor sperm and assisted reproduction with donor sperm. This case underscores the difficulties associated with delayed diagnosis.

CONCLUSION

Highlights the importance of adopting an approach that addresses fertility concerns along with endocrine issues and psychological support when managing de la Chapelle Syndrome.

A Case of de la Chapelle Syndrome

A rare disorder of sex development (DSD) linked to a 46,XX karyotype is characterized by male external genitalia, which can range from typical to atypical, often accompanied by testosterone deficiency. A 3-year-old child who appeared phenotypically male was brought to the hospital by his parents due to concerns about ambiguous genitalia. A comprehensive series of pathological tests and radiological imaging studies were conducted to ascertain the underlying cause of his presentation. Karyotyping revealed a 46,XX genotype, while magnetic resonance imaging (MRI) results indicated the presence of both testes and a Müllerian remnant. Consequently, the diagnosis was established as the de la Chapelle syndrome. This case report aims to highlight various imaging findings associated with this syndrome.

A Rare Presentation of Disorder of Sex Development

Disorder of sex development (DSD) is the term ascribed to a wide group of disorders presenting with congenital discord between chromosomal sex and phenotypic manifestation. Its incidence is 1 in 4500 births. 46 XX testicular DSD is a rare disorder characterized by the discordance between female karyotype and male phenotype. Its incidence is 1:20,000 to 25,000 male infants. It is further classified into SRY positive and SRY negative individuals, depending on the presence or absence of sex-determining region Y gene (SRY) on the X chromosome as a result of translocation. We are hereby reporting a rare case of de la Chapelle syndrome (SRY negative). A 30-year-old phenotypical male presented to us with complaints of primary infertility. He had had hypospadias during his childhood and underwent corrective surgery at the age of 18 years. For the previous 1.5 years, he had been complaining of decreased libido, difficulty in micturition, and presence of watery ejaculate. On examination, he had bilateral palpable testis with the testicular volume of 7 mL each, curved micropenis with chordee, and eccentric meatus with fistula. Semen analysis revealed azoospermia and hormonal profile was consistent with hypergonadotropic hypogonadism. His karyotyping turned out to be 46 XX chromosome without the SRY gene on polymerase chain reaction (PCR) array. He was medically treated with testosterone and underwent surgical correction of chordee.  The SRY negative testicular 46 XX disorder is a rare expression and can be diagnosed at the time of birth with the presence of severe hypospadias, cryptorchidism, or ambiguous genitalia. All new-borns with these findings should undergo evaluation for the disorder of sexual development. Such individuals can never father a child and genetic counseling should be offered. Infertility is the main concern for such individuals which can be addressed by in vitro fertilization (IVF) with a sperm donor or adoption.

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.

Ten cases with 46,XX testicular disorder of sex development: single center experience

Objective

To present clinical, chromosomal and hormonal features of ten cases with SRY-positive 46,XX testicular disorder of sex development who were admitted to our infertility clinic.

Cases and Methods

Records of the cases who were admitted to our infertility clinic between 2004 and 2015 were investigated. Ten 46,XX testicular disorder of sex development cases were detected. Clinical, hormonal and chromosomal assessments were analized.

Results

Mean age at diagnosis was 30.4, mean body height was 166.9cm. Hormonal data indicated that the patients had a higher FSH, LH levels, lower TT level and normal E2, PRL levels. Karyotype analysis of all patients confirmed 46,XX karyotype, and FISH analysis showed that SRY gene was positive and translocated to Xp. The AZFa, AZFb and AZFc regions were absent in 8 cases. In one case AZFb and AZFc incomplete deletion and normal AZFa region was present. In the other one all AZF regions were present.

Conclusion

Gonadal development disorders such as SRY-positive 46,XX testicular disorder of sex development can be diagnosed in infertility clinics during infertility work-up. Although these cases had no chance of bearing a child, they should be protected from negative effects of testosterone deficiency by replacement therapies.

XX testicular disorder of sex differentiation: case report

The 46 XX, testicular sex differentiation disorder, or XX male syndrome, is a rare condition detected by cytogenetics, in which testicular development occurs in the absence of the Y chromosome. It occurs in 1:20,000 to 25,000 male newborns and represents 2% of cases of male infertility. About 90% of individuals present with normal phenotype at birth and are generally diagnosed after puberty for hypoganadism, gynecomastia, and/or infertility. The authors present the report of an XX male with complete masculinization and infertility.

Sex Chromosome Mosaicism in the Gonads of DSD Patients: A Karyotype/Phenotype Correlation

Sex chromosome mosaicism results in a large clinical spectrum of disorders of sexual development (DSD). The percentage of 45,X cells in the developing gonad plays a major role in sex determination. However, few reports on the gonadal mosaic status have been published, and the phenotype is usually correlated with peripheral lymphocyte karyotypes, which makes the phenotype prediction imprecise. This study was conducted on 7 Egyptian DSD patients to demonstrate the effect of sex chromosome constitution of both blood lymphocytes and gonadal tissues on the phenotypic manifestations. Conventional cytogenetic and FISH analyses of blood lymphocytes were conducted, and laparoscopy with gonadal biopsy was performed for histopathologic examination and FISH analysis. Gonosomal mosaicism was detected in 3 patients who had a non-mosaic chromosome pattern in blood lymphocytes. Two patients showed the same type of sex chromosome mosaicism in both the blood and gonadal tissues but with different distributions. Two other patients revealed a non-mosaic pattern in both tissues. The present study elucidates the importance of examining sex chromosome mosaicism in gonadal tissues of DSD patients and highlights the critical role of 45,X mosaicism which can lead to serious effects during early gonadal organogenesis.

A duplication upstream of SOX9 was not positively correlated with the SRY‑negative 46,XX testicular disorder of sex development: A case report and literature review

The 46,XX male disorder of sex development (DSD) is rarely observed in humans. Patients with DSD are all male with testicular tissue differentiation. The mechanism of sex determination and differentiation remains to be elucidated. In the present case report, an 46,XX inv (9) infertile male negative for the sex‑determining region of the Y chromosome (SRY) gene was examined. This infertile male was systemically assessed by semen analysis, serum hormone testing and gonadal biopsy. Formalin‑fixed and paraffin‑embedded gonad tissues were assessed histochemically. The SRY gene was analyzed by fluorescence in situ hybridization (FISH) and polymerase chain reaction (PCR). The other 23 specific loci, including the azoospermia factor region on the Y chromosome and the sequence-targeted sites of the SRY‑box 9 (SOX9) gene were analyzed by PCR. The genes RSPO1, DAX1, SOX3, ROCK, DMRT1, SPRY2 and FGF9 were also assessed using sequencing analysis. Affymetrix Cytogenetics Whole Genome 2.7 M Arrays were used for detecting the genomic DNA from the patient and the parents. The patient with the 46,XX inv (9) (p11q13) karyotype exhibited male primary, however, not secondary sexual characteristics. However, the patient's mother with the 46, XX inv (9) karyotype was unaffected. The testicular tissue dysplasia of the patient was confirmed by tissue biopsy and absence of the SRY gene, and the other 23 loci on the Y chromosome were confirmed by FISH and/or PCR. The RSPO1, DAX1, SOX3, ROCK, DMRT1, SPRY2 and FGF9 genes were sequenced and no mutations were detected. A duplication on the 3 M site in the upstream region of SOX9 was identified in the patient as well as in the mother. The patient with the 46,XX testicular DSD and SRY‑negative status was found to be infertile. The duplication on the 3 M site in the upstream region of SOX9 was a polymorphism, which indicated that the change was not a cause of 46,XX male SDS. These clinical, molecular and cytogenetic findings suggested that other unidentified genetic or environmental factors are significant in the regulation of SDS.

46,XX testicular disorder of sexual development with SRY-negative caused by some unidentified mechanisms: a case report and review of the literature

Background

46,XX testicular disorder of sex development is a rare genetic syndrome, characterized by a complete or partial mismatch between genetic sex and phenotypic sex, which results in infertility because of the absence of the azoospermia factor region in the long arm of Y chromosome.

Case presentation

We report a case of a 14-year-old male with microorchidism and mild bilateral gynecomastia who referred to our hospital because of abnormal gender characteristics. The patient was treated for congenital scrotal type hypospadias at the age of 4 years. Semen analysis indicated azoospermia by centrifugation of ejaculate. Levels of follicle-stimulating hormone and luteinizing hormone were elevated, while that of testosterone was low and those of estradiol and prolactin were normal. The results of gonadal biopsy showed hyalinization of the seminiferous tubules, but there was no evidence of spermatogenic cells. Karyotype analysis of the patient confirmed 46,XX karyotype and fluorescent in situ hybridization analysis of the sex-determining region Y (SRY) gene was negative. Molecular analysis revealed that the SRY gene and the AZFa, AZFb and AZFc regions were absent. No mutation was detected in the coding region and exon/intron boundaries of the RSPO1, DAX1, SOX9, SOX3, SOX10, ROCK1, and DMRT genes, and no copy number variation in the whole genome sequence was found.

Conclusion

This study adds a new case of SRY-negative 46,XX testicular disorder of sex development and further verifies the view that the absence of major regions from the Y chromosome leads to an incomplete masculine phenotype, abnormal hormone levels and infertility. To date, the mechanisms for induction of testicular tissue in 46,XX SRY-negative patients remain unknown, although other genetic or environmental factors play a significant role in the regulation of sex determination and differentiation.

46,XX male disorder of sexual development:a case report

The main factor influencing sex determination of an embryo is the sex-determining region Y (SRY), a master regulatory gene located on the Y chromosome. The presence of SRY causes the bipotential gonad to differentiate into a testis. However, some individuals carry a Y chromosome but are phenotypically female (46,XY females) or have a female karyotype but are phenotypically male (46,XX males). 46, XX male is rare (1:20 000 in newborn males), and SRY positivity is responsible for this condition in approximately 90% of these subjects. External genitalia of 46,XX SRY-positive males appear as normal male external genitalia, and such cases are diagnosed when they present with small testes and/or infertility after puberty. Herein, we report an adolescent who presented with low testicular volume and who was diagnosed as a 46,XX male. SRY positivity was demonstrated in the patient by fluorescence in situ hybridization method.

Clinical, cytogenetic, and molecular analysis with 46,XX male sex reversal syndrome: case reports

PURPOSE

To investigate the clinical characteristics of different categories of sex-reversed 46,XX individuals and their relationships with chromosomal karyotype and the SRY gene.

METHODS

Chromosome karyotyping for peripheral blood culture and multi-PCR and FISH were performed.

RESULTS

Endocrinological data showed that their endocrine hormone levels were similar to that observed for Klinefelter syndrome, with higher FSH and LH levels and lower T levels. Chromosome karyotyping for peripheral blood culture revealed 46, XX complement for 11 males. Molecular studies showed that there were locus deletions at SY84, SY86, SY127, SY134, SY254 and SY255 in AZF on chromosome Y in 9 cases, with the SRY gene present at the terminus of the X chromosome short arm. In one case, besides 6 locus deletions in AZF, there was also SRY gene deletion. In another case, there were locus deletions only at SY254 and SY255, with SY84, SY86, SY127 SY134 loci and SRY present.

CONCLUSIONS

The majority (10/11) of 46,XX males were SRY positive, with the SRY gene translocated into the terminus of the X chromosome short arm. These patients were caused mainly by an X/Y chromosomal inter-change during paternal meiosis, leading to the differentiation of primary gonads into testes. Only a single patient (1/11) was SRY-negative, in which there might be some unknown downstream genes involved in sex determination.

A comprehensive review of genetics and genetic testing in azoospermia

Azoospermia due to obstructive and non-obstructive mechanisms is a common manifestation of male infertility accounting for 10-15% of such cases. Known genetic factors are responsible for approximately 1/3 of cases of azoospermia. Nonetheless, at least 40% of cases are currently categorized as idiopathic and may be linked to unknown genetic abnormalities. It is recommended that various genetic screening tests are performed in azoospermic men, given that their results may play vital role in not only identifying the etiology but also in preventing the iatrogenic transmission of genetic defects to offspring via advanced assisted conception techniques. In the present review, we examine the current genetic information associated with azoospermia based on results from search engines, such as PUBMED, OVID, SCIENCE DIRECT and SCOPUS. We also present a critical appraisal of use of genetic testing in this subset of infertile patients.

Genes and phenotypes of the human Y chromosome

By 1959 it was recognized that the gene (or genes) responsible for initiating the human male phenotype were carried on the Y chromosome. But in subsequent years, few phenotypes were associated with the Y chromosome. Recently, using molecular techniques combined with classical genetics, the Y chromosome has been the focus of intensive and productive investigation. Some of the findings are unexpected and have extended our understanding of the functions of the human Y chromosome. The notion that the Y chromosome is largely devoid of genes is changing. At the present, over 20 Y chromosome genes or pseudogenes have been identified or cloned, a number that is rapidly increasing. A high proportion of Y chromosome sequences have been found to be related to X chromosome sequences: the assembly of a complete physical map of the Y chromosome euchromatic region (believed to carry all of the genes) has shown 25% of the region studied to have homology to the X chromosome.3 Several X-homologous genes are located in the X and Y chromosome pairing regions, an area predicted to have shared homology. Surprisingly, some of the Y-encoded genes that lie outside of the X and Y pairing region share high sequence similarity, and in at least one case, functional identity, with genes on the X chromosome.

Genetic characterization of two 46,XX males without gonadal ambiguities

PURPOSE

To evaluate hypotheses which explain phenotypic variability in sex determining region Y positive 46,XX males. We investigate two 46,XX males without gonadal ambiguities.

METHODS

Cytogenetic and molecular analyses were used to identify the presence of Y chromosome material and to map the translocation breakpoint. Finally, the pattern of X chromosome inactivation was studied using the methylation assay at the androgen receptor locus.

RESULTS

The presence of Y chromosome material, including the sex determining region Y gene, was demonstrated in both men. However, the amount of translocated Y chromosome material differed between the patients. Different X chromosome inactivation patterns were found in the patients; random in one patient and non-random in the other.

CONCLUSIONS

We found a lack of association between phenotype and X chromosome inactivation pattern. Our cytogenetic and molecular analyses show support for the position effect hypothesis explaining the phenotypic variability in XX males.

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

BACKGROUND

In mammals, gonadal sex is normally determined by the presence or absence of the Y chromosome gene SRY. After expression of SRY in the sexually indifferent gonad, a number of genes encoding transcription factors and growth factors implicated in testis differentiation start to show male-specific expression. However, in XX males, these genes must be up-regulated in the absence of SRY, but the aetiology of SRY-negative XX maleness remains unclear.

AIM AND METHODS

We examined the expression of representative gonad marker genes in SRY-negative XX male testes.

RESULTS

RT-PCR and immunohistochemical studies revealed that SOX9, DAX-1, Ad4BP/SF-1, WT-1, GATA-4 and MIS were expressed in testicular tissues of SRY-negative XX males. Expression levels of SOX9 in testes of these patients averaged 1.9-fold higher than in normal XY testes, while expression levels of Ad4BP/SF-1, DAX-1 and MIS were lower in the SRY-negative XX testes than in XY testes. All XX patients were found to carry two copies of the SOX9 gene per diploid genome as do normal XX females and XY males. The XX male patients also carried two copies of the DAX-1 gene as do normal XX females, while normal XY males carry a single DAX-1 gene.

CONCLUSIONS

Our data suggest that lesions affecting SOX9 expression are the key factor in sex determination in SRY-negative XX males, and that the decreased expression of Ad4BP/SF-1, DAX-1 and MIS contribute to their clinical features.

An XX male with the sex-determining region Y gene inserted in the long arm of chromosome 16

OBJECTIVE

To report a case of a 46,XX male with an insertion of the sex-determining region Y (SRY) region in the terminal end of the long arm of chromosome 16.

DESIGN

Case report.

SETTING

Molecular and cytogenetic units in a university hospital.

PATIENT(S)

An infertile male, with normal masculinization of the external genitalia, who was referred for chromosomal analysis as an unaffected member of a family with idiopathic hypertrophic osteoarthropathy.

INTERVENTION(S)

Cytogenetic investigation, physical examination, and hormonal assays.

MAIN OUTCOME MEASURE(S)

Chromosomal analysis using GTG banding and fluorescence in situ hybridization (FISH).

RESULT(S)

Conventional chromosome analysis revealed a normal 46,XX karyotype. The FISH with bacterial artificial chromosomes (BACs) of the SRY region indicated the presence of this region on the terminal end of the long arm of chromosome 16.

CONCLUSION(S)

This is the first case of a 46,XX male with the SRY gene present on an autosome-here chromosome 16. The size of the inserted region containing SRY, inserted in 16qter, is approximately 600 kb.

[XX male: 3 case reports during childhood]

We report on three patients with the clinical condition known as "XX male", which is uncommon in the pediatric age group. Patients have a male phenotype (usually without ambiguous genitalia) and testes; however, the karyotype is 46,XX. The diagnosis is usually made in adult life due to infertility; it may also be done by the pediatrician when there is ambiguous genitalia or gynecomastia. The SRY gene (Sex-determining Region of the Y chromosome) is detected in most cases, thus explaining the origin of testicular development; however, it is absent in 20% of the cases, thus indicating that gonadal determination is a complex process which depends on the interaction of many genes and transcription factors. The finding of only 3 cases in two reference services in a 30-year period indicates the rarity of this disorder among intersex cases.

Clinical, hormonal and cytogenetic evaluation of 46,XX males and review of the literature

The main factor influencing the sex determination of an embryo is the genetic sex determined by the presence or absence of the Y chromosome. However, some individuals carry a Y chromosome but are phenotypically female (46,XY females) or have a female karyotype but are phenotypically male (46,XX males). 46,XX maleness is a rare sex reversal syndrome affecting 1 in 20,000 newborn males. Molecular analysis of sex-reversed patients led to the discovery of the SRY gene (sex-determining region on Y). The presence of SRY causes the bipotential gonad to develop into a testis. The majority of 46, SRY-positive XX males have normal genitalia; in contrast SRY-negative XX males usually have genital ambiguity. A small number of SRY-positive XX males also present with ambiguous genitalia. Phenotypic variability observed in 46,XX sex reversed patients cannot be explained only by the presence or absence of SRY despite the fact that SRY is considered to be the major regulatory factor for testis determination. There must be some other genes either in the Y or other autosomal chromosomes involved in the definition of phenotype. In this article, we evaluate four patients with 46,XX male syndrome with various phenotypes. Two of these cases are among the first reported to be diagnosed prenatally.

Three new 46,XX male patients: a clinical, cytogenetic and molecular analysis

BACKGROUND

XX males range phenotypically from completely masculinised individuals to true hermaphrodites and include a subset of SRY negative patients. The correlation between genotype (SRY+/-) and phenotype is still unclear.

AIM

To report three new patients with this rare condition, one of whom was diagnosed prenatally and another was SRY negative, and to verify in our patients whether the presence of SRY results in a more masculinised phenotype.

PATIENTS AND METHODS

We present two phenotypically normal XX male patients (10 and 13.5 years) and one 3.1 years old XX male with ambiguous external male genitalia Prader IV. The patients were diagnosed by clinical, hormonal, sonographic, genetic and histological criteria.

RESULTS

Basal hormonal status was normal for phenotype but an excessive response to GnRH testing was noticed in the second patient together with insufficient hCG stimulation in all three patients. Pelvic ultrasound displayed male structures without Müllerian ducts; testicular biopsy, performed only in the intersex patient, showed Sertoli and Leydig cell hypoplasia. Chromosome analysis confirmed 46,XX karyotype. FISH analysis and molecular analysis by PCR were positive for Yp fragments/SRY gene on Xp in two patients and negative in the patient with ambiguous external genitalia.

CONCLUSIONS

In our observation Y chromosome-specific material containing the SRY gene translocated to the X chromosome results in a completely masculinised phenotype. In the intersex patient, incomplete masculinisation without SRY suggests a mutation of one or more downstream non-Y testis-determining genes.

True hermaphroditism with ambiguous genitalia due to a complicated mosaic karyotype: clinical features, cytogenetic findings, and literature review

Abnormal recombination between the X and Y chromosomes during meiosis, occurring outside the pseudoautosomal region, can result in translocation of the SRY gene from the Y to the X chromosome, and consequently in abnormal sexual differentiation, such as the development of 46,XX males or true hermaphroditism. In this report we present clinical, cytogenetic, and molecular-cytogenetic data of a patient with ambiguous genitalia and true hermaphroditism, who had a unique mosaic karyotype, comprising three different cell lines: 46,XX(SRY+), 45,X(SRY+), and 45,X. The mosaic karyotype of our patient probably represents two different events: abnormal recombination between the X and Y chromosomes during paternal meiosis, and postzygotic loss of one of the X chromosomes. Replication studies demonstrated that in 80% of the XX cells, the SRY sequence was located on the active X chromosome. This finding suggests nonrandom X inactivation and, together with the presence of the SRY gene, explains the male phenotype of our patient. On the other hand, the presence of the 45,X cell line may have contributed to genital ambiguity. We conclude that fluorescence in situ hybridization (FISH) analysis with SRY probes is highly recommended and allows accurate diagnosis and optimal management in cases of 46,XX hermaphroditism and ambiguous genitalia.

Skewed X-chromosome inactivation pattern in SRY positive XX maleness: a case report and review of literature

XX maleness is the most common condition in which testes develop in the absence of a cytogenetically detectable Y chromosome. Using fluorescence in situ hybridization (FISH) or PCR, it was possible to detect the transfer of Yp fragments including SRY gene to the terminal part of X chromosome in the majority of XX males. We report a 32-year-old-male in whom a seminal analysis showed azoospermia, an X chromatin analysis showed 44% of Barr body positive nuclei and a chromosomal analysis revealed a 46,XX karyotype. Physical examination showed a normal sexual development and bilateral small testes. Hormonal studies revealed hypergonadotropic hypogonadism. Testis histological examination showed a profile of Sertoli Only Cell Syndrome. FISH study ruled out the presence of a Y-bearing cell line, and confirmed translocation of SRY to Xp terminal part. In order to confirm that the complete masculinized phenotype was related to a preferential inactivation of the no rearranged X chromosome, X-chromosome inactivation patterns (XCIP) were studied by analysis of methylation status of the androgen receptor gene. Highly skewed XCIP was observed by greater than 90% preferential inactivation involving one of the two X chromosomes, suggesting that the SRY-bearing X chromosome was the preferentially active X allowing for sufficient SRY expression for complete masculinization.

Velocardiofacial syndrome in an unexplained XX male

We report the unusual finding of velocardiofacial syndrome (VCF) in an unexplained 46,XX male. A microdeletion of 22q11.2 was confirmed by fluorescence in situ hybridization (FISH) analysis. Routine G-banded chromosome analysis revealed an XX sex chromosome constitution. FISH was performed using the SRY probe and failed to detect hybridization. The sex chromosome status of the patient was further investigated by PCR testing to screen for the presence of 24 distinct loci spanning the Y chromosome. PCR screening failed to detect any apparent Y chromosome material.

46,XX sex reversal

In humans, sexual differentiation is directed by SRY, a master regulatory gene located at the Y chromosome. This gene initiates the male pathway or represses the female pathway by regulating the transcription of downstream genes; however, the precise mechanisms by which SRY acts are largely unknown. Moreover, several genes have recently been implicated in the development of the bipotential gonad even before SRY is expressed. In some individuals, the normal process of sexual differentiation is altered and a sex reversal disorder is observed. These subjects present the chromosomes of one sex but the physical attributes of the other. Over the past years, considerable progress has been achieved in the molecular characterization of these disorders by using a combination of strategies including cell biology, animal models, and by studying patients with these pathologic entities.

Incomplete masculinisation of XX subjects carrying the SRY gene on an inactive X chromosome

46,XX subjects carrying the testis determining SRY gene usually have a completely male phenotype. In this study, five very rare cases of SRY carrying subjects (two XX males and three XX true hermaphrodites) with various degrees of incomplete masculinisation were analysed in order to elucidate the cause of sexual ambiguity despite the presence of the SRY gene. PCR amplification of 20 Y chromosome specific sequences showed the Yp fragment to be much longer in XX males than in true hermaphrodites. FISH analysis combined with RBG banding of metaphase chromosomes of four patients showed that in all three true hermaphrodites and in one XX male the Yp fragment was translocated onto a late replicating inactive X chromosome in over 90% of their blood lymphocytes. However, in a control classical XX male with no ambiguous features, the Yp fragment (significantly shorter than in the XX male with sexual ambiguity and only slightly longer than in XX hermaphrodites) was translocated onto the active X chromosome in over 90% of cells.

These studies strongly indicate that inactivation on the X chromosome spreading into a translocated Yp fragment could be the major mechanism causing a sexually ambiguous phenotype in XX (SRY+) subjects.

Molecular, cytogenetic, and clinical characterisation of six XX males including one prenatal diagnosis

Cytogenetic analysis, fluorescent in situ hybridisation (FISH), and molecular amplification have been used to characterise the transfer of Yp fragments to Xp22.3 in six XX males. PCR amplification of the genes SRY, RPS4Y, ZFY, AMELY, KALY, and DAZ and of several other markers along the Y chromosome short and long arms indicated the presence of two different breakpoints in the Y fragment. However, the clinical features were very similar in five of the cases, showing a male phenotype with small testes, testicular atrophy, and azoospermia. All these patients have normal intelligence and a stature within the normal male range. In the remaining case, the diagnosis was made prenatally in a fetus with male genitalia detected by ultrasound and a 46,XX karyotype in amniocytes and fetal blood. Molecular analysis of fetal DNA showed the presence of the SRY gene. FISH techniques also showed Y chromosomal DNA on Xp22.3 in metaphases of placental cells. To our knowledge, this is the second molecular prenatal diagnosis reported of an XX male.

The effects of aromatase and 5 alpha-reductase inhibitors, antiandrogen, and sex steroids on Bidder's organs development and gonadal differentiation in Bufo bufo tadpoles

Embryos of toads (Bufo bufo) were treated with aromatase (4-OHA) and 5 alpha-reductase (17 beta C) inhibitors, antiandrogen (CPA), estradiol-17 beta, testosterone, and 5 alpha-dihydrotestosterone in order to study the role played by sex steroids in the development and sex differentiation of gonads. Test compounds were administered to tadpoles in water and morphometric and cytometric analyses were carried out on histological sections of the cephalic Bidder's organ (a rudimentary ovary) and of the gonadal region. In Bidder's organs, the number and size of oogonia and oocytes were modified by the treatments. However, the female commitment of the Bidder's organ occurs independently from steroid treatments that lead to an acceleration or slackening of the processes of proliferation and differentiation of oogonia. 4-OHA and androgens caused various degrees of inhibition of ovarian differentiation, with gonads maintaining an undifferentiated condition. Estrogen provoked a shift of the sex ratio towards the female sex, yet slackened gonadal growth. 17 beta C accelerated ovarian differentiation in females while CPA enhanced gonadal differentiation in both sexes by promoting the germ and somatic cell proliferation. We suggest that sex hormones may have a local regulatory role in gonadal differentiation during early developmental stages. Furthermore, the strong tendency of Bidderian germ cells to develop in the oogenetic way regardless of sex genotype and steroid treatments, and the quantitative sex differences found in the control Bidder's organs and gonads, suggest that other factors (such as intracellular mechanisms) may be involved in the initial steps of the process of germ cell differentiation.

Regulation of sexual dimorphism in mammals

Sexual dimorphism in humans has been the subject of wonder for centuries. In 355 BC, Aristotle postulated that sexual dimorphism arose from differences in the heat of semen at the time of copulation. In his scheme, hot semen generated males, whereas cold semen made females (Jacquart, D., and C. Thomasset. Sexuality and Medicine in the Middle Ages, 1988). In medieval times, there was great controversy about the existence of a female pope, who may have in fact had an intersex phenotype (New, M. I., and E. S. Kitzinger. J. Clin. Endocrinol. Metab. 76: 3-13, 1993.). Recent years have seen a resurgence of interest in mechanisms controlling sexual differentiation in mammals. Sex differentiation relies on establishment of chromosomal sex at fertilization, followed by the differentiation of gonads, and ultimately the establishment of phenotypic sex in its final form at puberty. Each event in sex determination depends on the preceding event, and normally, chromosomal, gonadal, and somatic sex all agree. There are, however, instances where chromosomal, gonadal, or somatic sex do not agree, and sexual differentiation is ambiguous, with male and female characteristics combined in a single individual. In humans, well-characterized patients are 46, XY women who have the syndrome of pure gonadal dysgenesis, and a subset of true hermaphrodites are phenotypic men with a 46, XX karyotype. Analysis of such individuals has permitted identification of some of the molecules involved in sex determination, including SRY (sex-determining region Y gene), which is a Y chromosomal gene fulfilling the genetic and conceptual requirements of a testis-determining factor. The purpose of this review is to summarize the molecular basis for syndromes of sexual ambiguity seen in human patients and to identify areas where further research is needed. Understanding how sex-specific gene activity is orchestrated may provide insight into the molecular basis of other cell fate decisions during development which, in turn, may lead to an understanding of aberrant cell fate decisions made in patients with birth defects and during neoplastic change.

Genetic causes of male infertility

Male infertility has often been ascribed to infections, immunologic factors, chemical insults or malformations. About 10% of infertile males have severe defects in sperm production. Lately, research has focused on possible genetic aetiologies. In this review genetic causes of male infertility are discussed. For pragmatic reasons three groups have been defined. In the first group, disorders of sexual differentiation associated with male infertility are considered. In the second group, male infertility is discussed in a context of some genetic diseases. In the third group, genetic causes for isolated defects of sperm production and function are reported.

Development in a 46 XX boy with positive SRY gene

We present the case of an 11 year-old boy, who asked for medical attention due to obesity and assumed underdeveloped external genitalia. He did not have genital anomalies, penile length was 5.3 cm, testicular volume 2 ml and pubic hair Tanner stage 1. His bone age was normal for chronological age. Endocrinological study showed normal results for his age. Karyotype revealed a 46 XX pattern. MRI of external genitalia showed bilateral scrotal testes which were normal in diameter for his age. The check of his historical growth chart and follow-up revealed normal growth with spontaneous pubertal development. However, hormonal studies showed progressive increase of FSH levels, indicative of failure of germinal epithelium. The presence of Y sequences, including SRY gene, was demonstrated by PCR. Our observation is in agreement with the view that 46 XX male subjects diagnosed at peripubertal age with the SRY gene in the genome have a good prognosis regarding growth and development, but the principal problem of these patients is infertility.

A male-specific role for SOX9 in vertebrate sex determination

Mutation analyses of patients with campomelic dysplasia, a bone dysmorphology and XY sex reversal syndrome, indicate that the SRY-related gene SOX9 is involved in both skeletal development and sex determination. To clarify the role SOX9 plays in vertebrate sex determination, we have investigated its expression during gonad development in mouse and chicken embryos. In the mouse, high levels of Sox9 mRNA were found in male (XY) but not female (XX) genital ridges, and were localised to the sex cords of the developing testis. Purified fetal germ cells lacked Sox9 expression, indicating that Sox9 expression is specific to the Sertoli cell lineage. Sex specificity of SOX9 protein expression was confirmed using a polyclonal antiserum. The timing and cell-type specificity of Sox9 expression suggests that Sox9 may be directly regulated by SRY. Male-specific expression of cSOX9 mRNA during the sex determination period was also observed in chicken genital ridges. The conservation of sexually dimorphic expression in two vertebrate classes which have significant differences in their sex determination mechanisms, points to a fundamental role for SOX9 in testis determination in vertebrates. Sox9 expression was maintained in the mouse testis during fetal and adult life, but no expression was seen at any stage by in situ hybridisation in the developing ovary. Male-specific expression was also observed in the cells surrounding the Mullerian ducts and in the epididymis, and expression in both sexes was detected in the developing collecting ducts of the metanephric kidney. These results suggest that SOX9 may have a wider role in the development of the genitourinary system.

Phenotypical expression in XX males correlates with testicular response to exogenous choriogonadotropin in early infancy: does a variable degree of testicular failure determine the degree of genital ambiguity?

The 46,XX male syndrome is characterized by the presence of testicular development in subjects who lack a Y chromosome. The majority of patients have male external genitalia without ambiguity; however, 10-15% show diverse degrees of hypospadias. Testicular function is normal at birth but deteriorates thereafter. However, it has not been clarified why some cases exhibit genital ambiguity. This study examined 10 affected patients, including 4 prepubertal (< 1 year old) with hypospadias (1 glandular, 1 penile, and 2 penoscrotal). In all subjects, testicular function was evaluated by performing a stimulation with choriogonadotropin. In the postpubertal individuals, basal and poststimuli testosterone were below the reference values. Prepubertal patients had age-appropriate basal test-osterone concentrations. All responded to the choriogonadotropin challenge; however, the most significant response was observed in the patient with the glandular hypospadias, the second highest response was presented by the patient with the penile hypospadias, while both patients with the penoscrotal hypospadias had the poorest responses. These results suggest that the degree of genital ambiguity is correlated with the impairment in testosterone response to choriogonadotropin in early infancy, indicating a defect in testosterone production in XX males with genital ambiguity.

Molecular analysis in true hermaphrodites with different karyotypes and similar phenotypes

True hermaphroditism is characterized by the development of ovarian and testicular tissue in the same individual. Müllerian and Wolffian structures are usually present, and external genitalia are often ambiguous. The most frequent karyotype in these patients is 46,XX or various forms of mosaicism, whereas 46,XX is very rarely found. The phenotype in all these subjects is similar. We studied 10 true hermaphrodites. Six of them had a 46,XX chromosomal complement: 3 had been reared as males and 3 as females. The other 4 patients were mosaics: 3 were 46,XX/46,XY and one had a 46,XX/47,XXY karyotype. One of the 46,XX/46,XY mosaics was reared as a female, whereas the other 3 mosaics were reared as males. The sex of assignment in the 10 patients depended only on labio-scrotal differentiation. Molecular studies in 46,XX subjects documented the absence of Y centromeric sequences in all cases, arguing against hidden mosaicism. One patient presented Yp sequences (ZFY+, SRY+), which contrast with South African black 46,XX true hermaphrodites in whom no Y sequences were found. Molecular analysis in the subjects with mosaicism demonstrated the presence of Y centromeric and Yp sequences confirming the presence of a Y chromosome. Gonadal development, endocrine function, and phenotype in the 10 patients did not correlate with the presence of a Y chromosome or Y-derived sequences in the genome, confirming that true hermaphroditism is a heterogeneous condition.

SRY-negative true hermaphrodites and an XX male in two generations of the same family

Two 46,XX true hermaphrodites and one XX male without genital ambiguities are reported. They coexist in two generations of the same pedigree, with paternal transmission and in the absence of SRY (sex-determining region, Y chromosome). These familial cases provide evidence to support the hypothesis that these disorders are alternative manifestations of the same genetic defect, probably an autosomal dominant mutation (with incomplete penetrance) or an X-linked mutation (limited by the presence of the Y chromosome).

Genetic mapping of the autosomal region involved in XX sex-reversal and horn development in goats

Contrary to other genetic disorders, the genetic study of sex determination anomalies in humans stumbles over the difficulty in observing large pedigrees. In goats, abnormalities in sex determination are intimately linked to a dominant Mendelian gene coding for the "polled" (hornless) character, which could render this species an interesting animal model for the rare human cases of SRY-negative XX males. In this report, we describe genetic linkage between the polled/intersex synchome (PIS) and four microsatellite markers of the distal region of goat Chromosome 1 (CHI1), quite distinct from the bovine "polled" region. According to comparative mapping data, no sex-determining gene has been described so far in homologous regions in the human. This genetic localization constitutes a first step towards identifying a new autosomal sex-determining gene in mammals.

Clinical traits and molecular findings in 46,XX males

46,XX maleness is characterized by the presence of testicular development in subjects who lack a Y chromosome. The majority of affected persons have normal external genitalia, but 10-15% show various degrees of hypospadias. Several hypotheses have been proposed to explain the etiology of this constitution: translocation of the testis-determining factor (TDF) from the Y to the X chromosome, mutation in an autosomal or X chromosomal gene which permits testicular determination in the absence of TDF, and undetected mosaicism with a Y-bearing cell line. We report the phenotypic data and results of molecular analyses performed in six sporadic Mexican males with 46,XX karyotype. Molecular studies revealed Yp sequences in two individuals (ZFY+ SRY+) with different phenotypes, a third one presented with a smaller segment of Yp (ZFY- SRY+) and complete virilization, while the remaining three were Y-negative and showed hypospadias. In all subjects a hidden mosaicism with a Y-bearing cell line was ruled out due to the absence of Y-centromeric sequences. Our data demonstrate that the phenotype does not always correlate with the presence or absence of Y-sequences in the genome, and confirm that 46,XX maleness is a genetically heterogeneous condition.

XX true hermaphroditism in southern African blacks: exclusion of SRY sequences and uniparental disomy of the X chromosome

A molecular investigation of 16 Bantu-speaking Black XX true hermaphrodites was undertaken in an attempt to determine the cause of the disorder. Y-specific sequences, including sequences mapping to the sex-determining region of the Y, were shown to be absent from lymphocyte tissue of all 16 patients tested. Y chromosome sequences were also absent from the ovarian and testicular components of both ovotestes of a single XX true hermaphrodite, thus excluding gonadal mosaicism involving Y chromosome sequences. Since there is evidence for Xp genes involved in testis determination/differentiation, uniparental disomy of the X chromosome was investigated in 14 XXTH families. Uniparental disomy was excluded in 12 of the 14 families, and isodisomy was excluded in the remaining two cases.

[Genetics of human sex determination and its disturbances]

The genetics of human sex determination is considered in view of the various disorders of gonad development. The Y chromosome plays an important role in the induction of sex determination by encoding the testis-determining factor (TDF). However, not all deviations in regular development can be explained by mutations of the TDF as unique factor. Therefore, it is necessary to postulate other mutations in still unknown genes of the cascade for male-specific determination as well as the requirement of an ovary-determining factor for regular female development.

Clinical and anatomical spectrum in XX sex reversed patients. Relationship to the presence of Y specific DNA-sequences

OBJECTIVE

Testicular differentiation can occur in the absence of the Y chromosome giving XX sex-reversed males. Although Y chromosomal sequences can be detected in the majority of male subjects with a 46,XX karyotype, several studies have shown that approximately 10% of patients lack Y material including the SRY gene. The aim of this study was to see if the classification of XX sex-reversed individuals into three groups, Y-DNA-positive phenotypically normal XX males, Y-DNA-negative XX males with genital ambiguities and Y-DNA-negative true hermaphrodites can be applied to our cases.

DESIGN

Endocrinological and genetic studies were conducted in 20 XX sex-reversed patients.

PATIENTS

Twenty patients with various phenotypes were studied. They were between 20 days and 35 years old. Ten presented ambiguous external genitalia (Prader's stages II to IV). After laparotomy or gonadal biopsy, the diagnosis was 46,XX true hermaphroditism in five, and XX male in 15.

MEASUREMENTS

Blood samples were obtained from all patients for hormonal and molecular studies. Basal levels of testosterone, oestradiol and pituitary gonadotrophins were measured by RIA. In addition, two stimulation tests were performed: gonadotrophin stimulation with GnRH and testicular stimulation with hCG. Several Y-specific DNA sequences of the short arm of the Y chromosome were analysed by Southern blot and polymerase chain reaction methods.

RESULTS

In this study, three categories of XX sex-reversed individuals were observed: phenotypically normal males with or without gynaecomastia, males with genital ambiguities, and true hermaphrodites. Endocrinological data were similar in XX males and in true hermaphrodites. Testosterone levels exhibited normal (n = 9) or decreased (n = 11) values. The hCG response was low. FSH and LH were elevated in 13 patients. Molecular analysis in ten patients showed varying amounts of Y material including the Y boundary and SRY. Ten patients with various phenotypes lacked Y chromosomal DNA. There was no relation between Leydig cell function (as indicated by testosterone levels before or after hCG stimulation) and the presence of Y chromosome material.

CONCLUSION

Although the presence of Y-specific DNA generally results in a more masculinized phenotype, exceptions do occur. In the Y-DNA-negative group, complete or incomplete masculinization in the absence of SRY suggests a mutation of one or more downstream non-Y, testis-determining genes.

True hermaphroditism: geographical distribution, clinical findings, chromosomes and gonadal histology

We reviewed 283 cases of human true hermaphroditism published from 1980 to 1992. Of the 96 cases described in Africa 96.9% showed a 46,XX karyotype. In Europe 40.5% of 74 cases and 21.0% of the patients in North America had chromosomal mosaicism. The 46,XY karyotype is extremely rare (7%) and equally distributed through Asia, Europe and North America. Of 283 cases 87 were of black or black mixed origin with a 46,XX chromosomal constellation. The most common gonad in patients with true hermaphroditism, an ovotestis, was found in 44.4% of 568 gonads. Gonads with testicular tissue were more frequent on the right side of the body, while pure ovarian tissue was more common on the left. Histologically the testicular tissue was described to be immature and only twice was spermatogenesis reported while the ovarian portion often appeared normal. This coincides with 21 pregnancies reported in ten true hermaphrodites while only one true hermaphrodite apparently has fathered a child. Of the patients 4.6% were reported to have gonadal tumours. Position and type of the genital ducts, frequency of clinical findings such as genital abnormalities and gynaecomastia, correlations between assigned sex and karyotype as well as the age at diagnosis are reported.

Familial true hermaphroditism: paternal and maternal transmission of true hermaphroditism (46,XX) and XX maleness in the absence of Y-chromosomal sequences

We report on 46,XX true hermaphroditism and 46,XX maleness coexisting in the same pedigree, with maternal as well as paternal transmission of the disorder. Molecular genetic analysis showed that both hermaphrodites as well as the 46,XX male were negative for Y-chromosomal sequences. Thus, this pedigree is highly informative and allows the following conclusions: first, the maternal as well as paternal transmission of the disorder allows the possibility of an autosomal dominant as well as an X-chromosomal dominant mode of inheritance; second, testicular determination in the absence of Y-specific sequences in familial 46,XX true hermaphrodites as well as in 46,XX males seems to be due to the varying expression of the same genetic defect; and third, there is incomplete penetrance of the defect.

A regulatory cascade hypothesis for mammalian sex determination: SRY represses a negative regulator of male development

The mammalian Y chromosome carries the SRY gene, which determines testis formation. Here we review data on individuals who are XX but exhibit male characteristics: some have SRY; others do not. We have analyzed three families containing more than one such individual and show that these individuals lack SRY. Pedigree analysis leads to the hypothesis that they carry recessive mutations (in a gene termed Z) that allow expression of male characteristics. We propose that wild-type Z product is a negative regulator of male sex determination and is functional in wild-type females. In males, SRY product represses or otherwise negatively regulates Z and thereby allows male sex determination. This hypothesis can also explain other types of sex reversal in mammals, in particular, XY females containing SRY. Some of these individuals may have mutations at the Z locus rendering them insensitive to SRY. Recessive mutations (such as the polled mutation of goats) leading to sex reversal are known in a variety of animals and might be used to map and ultimately clone the human Z gene.

Hormonal and molecular genetic findings in 46,XX subjects with sexual ambiguity and testicular differentiation

Ten patients were studied who had sexual ambiguity having in common a 46.XX karyotype and testicular tissue. They were aged from one month to 23 years; some of them were followed through puberty. Eight cases were sporadic and two familial. They were divided into two groups according to finding of surgery and histology: 46, XX males with sexual ambiguity and 46 XX true hermaphrodites (TH). They were no differences in phenotypes (except uterus and ovotestis in TH). The endocrinological data were identical in the two groups: testosterone levels were in the normal range during puberty, then decreased in adulthood. Gonadotrophins were above the normal range at mid-puberty. Gonadal biopsies, regardless of the ovarian part of the ovotestis, were identical in two groups, i.e., normal in the youngest patients, then spermatogonia disappeared afterwards and dysgenesis became obvious. In one case, the ovarian zone of the ovotestis was only detected on serial cuts after gonadectomy. Southern blots displayed the presence of Y specific material in tow cases (PABY-SRY-PO.9). Otherwise, in all other patients, there was the lack of any Y sequences without any differences between the two groups. These data suggests that 46, XX males with sexual ambiguity and 46 XX true hermaphrodites may be alternative expressions of two genetic defects: one, a minimal interchange between Yp and Xp, another, a mutation of an autosomal testis determining factor for the patients without Y detectable material.