SRY protein is expressed in ovotestis and streak gonads from human sex-reversal

In mammals, a master gene located on the Y chromosome, the testis-determining gene SRY, controls sex determination. SRY protein is expressed in the genital ridge before testis determination, and in the testis it is expressed in Sertoli and germ cells. Completely sex-reversed patients are classified as either 46,XX males or 46,XY females. SRY mutations have been described in only 15% of patients with 46,XY complete or partial gonadal dysgenesis. However, although incomplete or partial sex-reversal affects 46,XX true hermaphrodites, 46,XY gonadal dysgenesis, and 46,XX/46,XY mosaicism, only 15% of the 46,XX true hermaphrodites analyzed have the SRY gene. Here, we demonstrate that the SRY protein is expressed in the tubules of streak gonads and rete testis, indicating that the SRY protein is normally expressed early during testis determination. Based on these results, we propose that some factors downstream from SRY may be mutated in these 46,XY sex-reversal patients. We have also analyzed SRY protein expression in the ovotestis from 46,XX true hermaphrodites and 46,XX/46,XY mosaicism, demonstrating SRY protein expression in both testicular and ovarian portions in these patients. This suggests that the SRY protein does not inhibit ovary development. These results confirm that other factors are needed for complete testis development, in particular, those downstream of the SRY protein.     

Molecular analysis of SRY gene in patients with mixed gonadal dysgenesis.

Mixed gonadal dysgenesis (MGD) includes a group of heterogeneous conditions consisting of a dysgenetic testis with a streak gonad. MGD is probably due to a disturbance in testicular determination/differentiation. The objective of this study is to analyze the SRY gene in MGD patients. A molecular investigation was undertaken in sixteen patients with this disorder in an attempt to determine mutations in SRY through polymerase chain reaction, single strand conformational polymorphism and direct sequencing. Eleven patients showed 45,X/46,XY and five 46,XY karyotype. Mutations in SRY gene were shown to be absent in these patients. This study confirms the findings of other studies. The etiology of MGD is heterogeneous, and cytogenetics mosaicism typically seen in these patients may be a cause of this condition, although, the presence of mutations in testicular organizing genes downstream of SRY is still to rule out.     

Evidence for increased prevalence of SRY mutations in XY females with complete rather than partial gonadal dysgenesis.

The Y chromosome gene SRY (sex-determining region, Y gene) has been equated with the mammalian testis-determining factor. The SRY gene of five subjects with 46,XY complete gonadal dysgenesis (46,XY karyotype, completely female external genitalia, normal Müllerian ducts, and streak gonads) was evaluated for possible mutations in the coding region by using both single-strand conformation polymorphism (SSCP) assay and DNA sequencing. Mutations were identified in three subjects, of which two gave altered SSCP patterns. Two of them were point mutations causing amino acid substitutions, and the third was a single-base deletion causing a frameshift. All three mutations caused alterations in the putative DNA-binding region of the SRY protein. Genomic DNA was obtained from the fathers of two of the three mutant patients: one mutation was demonstrated to be de novo, and the other was inherited. The presence of SRY mutations in three of five patients suggests that the frequency of SRY mutations in XY females is higher than current estimates.     

A novel missense mutation (S18N) in the 5′ non-HMG box region of the SRY gene in a patient with partial gonadal dysgenesis and his normal male relatives

Mutations in the sex-determining region of the Y chromosome (the SRY gene) have been reported in low frequency in patients with 46,XY gonadal dysgenesis. We investigated 21 Brazilian 46,XY sex-reversed patients, who presented either complete or partial gonadal dysgenesis or embryonic testicular regression syndrome. Using Southern blotting, polymerase chain reaction, denaturing gradient gel electrophoresis and direct sequencing, we analyzed deletions and point mutations in the SRY gene. We found a missense mutation at codon 18 upstream of the 5′ border of the HMG box of the SRY gene in one patient with partial gonadal dysgenesis. This variant sequence was also found in DNA obtained from blood and sperm cells of his father and in blood cells of his normal brother. The S18N mutation was not found in 50 normal males, ruling out the possibility of a common polymorphism. We identified a novel familial missense mutation (S18N) in the 5’ non-HMG box of the SRY gene in 1 of 21 patients with 46,XY sex reversal. Received: 6 May 1997 / Accepted: 2 October 1997     

Aberrant testicular differentiation in 46,XY gonadal dysgenesis: Morphology,endocrinology, serology

Summary In an infant with gonadal dysgenesis and somatic anomalies, the internal and external genitalia were female but the gonads contained tubular structures suggesting male differentiation. The karyotype was 46,XY with no evidence of structural aberration or mosaicism. Hormonal metabolism and H-Y antigen expression were assayed in cultured gonadal cells. Although unable to synthesize testosterone, the cultured cells were able to convert it to dihydrotestosterone. H-Y antigen was present, perhaps at a level lower than that in cells from normal XY males. Our observations indicate that a modicum of testicular organogenesis may precede the involution that results in a streak gonad in some cases of gonadal dysgenesis.     

Monozygotic twins of opposite sex

Although discordant karyotypes are known in identical twins, cases involving differences in sex phenotype are rare. We studied identical twins with the 46,XY karyotype - a male with mixed gonadal dysgenesis and a female with "pure" gonadal dysgenesis. The testis-determining SRY gene was present in DNA from both twins but no mutations were detected in the SRY conserved motif. Monozygosity was indicated by short tandem repeat polymorphism analysis. These observations could be attributed to (i) mutation and mosaicism involving "downstream" sex-determining loci, (ii) variable penetrance of genes such as DSS/NR0B1, duplication of which can disrupt the male-determining pathway, or (iii) occurrence of cryptic 45,X gonadal cell lines.     

An SRY-negative 47,XXY mother and daughter

Females with XY gonadal dysgenesis are sterile, due to degeneration of the initially present ovaries into nonfunctional streak gonads. Some of these sex-reversal cases can be attributed to mutation or deletion of the SRY gene. We now describe an SRY-deleted 47,XXY female who has one son and two daughters, and one of her daughters has the same 47,XXY karyotype. PCR and FISH analysis revealed that the mother carries a structurally altered Y chromosome that most likely resulted from an aberrant X-Y interchange between the closely related genomic regions surrounding the gene pair PRKX and PRKY on Xp22.3 and Yp11.2, respectively. As a consequence, Yp material, including SRY, has been replaced by terminal Xp sequences up to the PRKX gene. The fertility of the XXY mother can be attributed to the presence of the additional X chromosome that is missing in XY gonadal dysgenesis females. To our knowledge, this is the first human XXY female described who is fertile.     

Complete XY gonadal dysgenesis due to p.D293N homozygous mutation in theNR5A1 gene: a case study

TheSRY gene (sex-determining region on the Y chromosome; MIM *480000) is responsible for initiating male gonadal development. However, only 15–20% of the cases of XY gonadal dysgenesis are due to mutations in its sequence. Recently, heterozygous mutations in theNR5A1 gene (nuclear receptor subfamily 5, group A, member 1; MIM +184757) have been described in association with ovarian failure and disorders of testis development with or without adrenal failure. Here we describe a case of XY complete gonadal dysgenesis due to a p.D293N homozygous mutation in theNR5A1 gene, with normalSRY and no adrenal failure.     

A 46,XY female DSD patient with bilateral gonadoblastoma, a novel SRY missense mutation combined with a WT1 KTS splice-site mutation

Patients with Disorders of Sex Development (DSD), especially those with gonadal dysgenesis and hypovirilization are at risk of developing malignant type II germ cell tumors/cancer (GCC) (seminoma/dysgerminoma and nonseminoma), with either carcinoma in situ (CIS) or gonadoblastoma (GB) as precursor lesion. In 10-15% of 46,XY gonadal dysgenesis cases (i.e., Swyer syndrome), SRY mutations, residing in the HMG (High Mobility Group) domain, are found to affect nuclear transport or binding to and bending of DNA. Frasier syndrome (FS) is characterized by gonadal dysgenesis with a high risk for development of GB as well as chronic renal failure in early adulthood, and is known to arise from a splice site mutation in intron 9 of the Wilms' tumor 1 gene (WT1). Mutations in SRY as well as WT1 can lead to diminished expression and function of SRY, resulting in sub-optimal SOX9 expression, Sertoli cell formation and subsequent lack of proper testicular development. Embryonic germ cells residing in this unfavourable micro-environment have an increased risk for malignant transformation. Here a unique case of a phenotypically normal female (age 22 years) is reported, presenting with primary amenorrhoea, later diagnosed as hypergonadotropic hypogonadism on the basis of 46,XY gonadal dygenesis with a novel missense mutation in SRY. Functional in vitro studies showed no convincing protein malfunctioning. Laparoscopic examination revealed streak ovaries and a normal, but small, uterus. Pathological examination demonstrated bilateral GB and dysgerminoma, confirmed by immunohistochemistry. Occurrence of a delayed progressive kidney failure (focal segmental glomerular sclerosis) triggered analysis of WT1, revealing a pathogenic splice-site mutation in intron 9. Analysis of the SRY gene in an additional five FS cases did not reveal any mutations. The case presented shows the importance of multi-gene based diagnosis of DSD patients, allowing early diagnosis and treatment, thus preventing putative development of an invasive cancer.     

Description and molecular analysis of SRY and AR genes in a patient with 46,XY pure gonadal dysgenesis (Swyer syndrome)

46,XY pure gonadal dysgenesis, first described in 1955 by Swyer, results from testicular tissue loss during the first 8 weeks of fetal life, a critical period for male differentiation. We describe a case of an 18 years old patient presented to us with a chief complain of primary amenorrhea. Chromosomal analysis revealed a 46,XY karyotype. A molecular investigation was undertaken in an attempt to determine mutations in SRY and AR genes through DNA sequencing. Mutations were shown to be absent. The molecular basis of Swyer syndrome is still unknown, although the presence of mutations in testicular organizing genes downstream of SRY is still to rule out. The patient, who is considered as female, was placed on estrogen replacement therapy, while bilateral prophylactic laparoscopic gonadectomy was programmed due to the high prevalence of gonadal tumors in this syndrome. No signs of malignance were detected in the gonadal tissue, which predicts that an intact SRY gene is usually, but not always, not related to the formation of malignancies like dysgeminomas or gonadoblastomas.     

A novel mutation (c. 341A>G) in the SRY gene in a 46,XY female patient with gonadal dysgenesis

SRY (sex-determining region Y) gene, MIM 480000, NM_005634) is crucial for sex differentiation which encodes the protein responsible for initiating testis differentiation. SRY mutations are associated with the presence of XY gonadal dysgenesis symptoms.     

St?rungen der m?nnlichen Gonadendifferenzierung

XY gonadal dysgenesis is characterized by a failure of testis differentiation and can be caused either by disturbed development of the urogenital ridge to the bipotential gonad or by impaired differentiation of the bipotential gonad to testis. Genes responsible for early gonadal development like WT1 and SF1 can be distinguished from genes involved in testis differentiation such as SRY, SOX9, DMRT, DAX1, WNT4, DHH, CBX2, TSPYL1, ATRX and ARX. In complete XY gonadal dysgenesis, M??llerian but no Wolffian structures are present. In partial XY gonadal dysgenesis, remnants of M??llerian and Wolffian ducts can be present and virilization of the external genitalia can take place. In about a third of cases, XY gonadal dysgenesis occurs in a syndromic form. In these syndromic forms, the extragenital phenotypes can indicate the causative genes, but these genes can also cause non-syndromic forms of XY gonadal dysgenesis.     

Asymmetrical gonadal dysgenesis. Report of a case (author's transl)]

The authors report a case of asymmetrical gonadal dysgenesis related to 45XO-46XY mosaicism in a 16 year old girl. Delayed growth and puberty, Turner's dysmorphism without sexual ambiguity and skeletal abnormalities are the main clinical features suggesting the diagnosis. Exploratory laparotomy reveals infantil uterus, bilateral fallopian tubes and streak gonads. A right dysgenetic testis is identified on electron microscopic examination. Theories on pathogenesis of this unusual genetic defect are discussed.     

H-Y antigen in 46,XY gonadal dysgenesis

Summary Presence of H-Y antigen has been correlated with testicular differentiation, and absence of H-Y with failure of testicular differentiation, in a variety of mammalian species. To determine more precisely the relationship between expression of H-Y antigen and development of the testis, we studied the cells of phenotypic females with the 46,XY male karyotype. Blood leukocytes were typed H-Y⁺ in five XY females with gonadal dysgenesis, although in other studies blood leukocytes from XY females with gonadal dysgenesis were typed H-Y^-. Thus mere presence of H-Y antigen is not sufficient to guarantee normal differentiation of the testis. In the present paper we review evidence for an additional factor in gonadal organogenesis, the H-Y antigen receptor. We infer that testicular development requires engagement of H-Y and its receptor. It follows that XY gonadal dysgenesis is the consequence of functional absence of the H-Y testis inducer as in the following conditions: failure of synthesis of H-Y or failure of specific binding of H-Y.     

Mutation analysis of subjects with 46, XX sex reversal and 46, XY gonadal dysgenesis does not support the involvement of SOX3 in testis determination

Despite the identification of an increasing number of genes involved in sex determination and differentiation, no cause can be attributed to most cases of 46, XY gonadal dysgenesis, approximately 20% of 46, XX males and the majority of subjects with 46, XX true hermaphroditism. Perhaps the most interesting candidate for involvement in sexual development is SOX3, which belongs to the same family of proteins (SOX) as SRY and SOX9, both of which are involved in testis differentiation. As SOX3 is the most likely evolutionary precursor to SRY, it has been proposed that it has retained a role in testis differentiation. Therefore, we screened the coding region and the 5 and 3 flanking region of the SOX3 gene for mutations by means of single-stranded conformation polymorphism and heteroduplex analysis in eight subjects with 46, XX sex reversal (SRY negative) and 25 subjects with 46, XY gonadal dysgenesis. Although no mutations were identified, a nucleotide polymorphism (1056C/T) and a unique synonymous nucleotide change (1182A/C) were detected in a subject with 46, XY gonadal dysgenesis. The single nucleotide polymorphism had a heterozygosity rate of 5.1% (in a control population) and may prove useful for future X-inactivation studies. The absence of SOX3 mutations in these patients suggests that SOX3 is not a cause of abnormal male sexual development and might not be involved in testis differentiation.An erratum to this article can be found at     

Molecular analysis in true hermaphroditism: demonstration of low-level hidden mosaicism for Y-derived sequences in 46,XX cases

True hermaphroditism (TH) is an unusual form of sex reversal, characterized by the development of testicular and ovarian tissue in the same subject. Approximately 60% of the patients have a 46,XX karyotype, 33% are mosaics with a second cell line containing a Y chromosome, while the remaining 7% are 46,XY. Molecular analyses have demonstrated that SRY is present in only 10% of TH with a 46,XX karyotype; therefore, in the remaining 90%, mutations at unknown X-linked or autosomal sex determining loci have been proposed as factors responsible for testicular development. True hermaphroditism presents considerable genetic heterogeneity with several molecular anomalies leading to the dual gonadal development as SRY point mutations or SRY hidden gonadal mosaicism. In order to identify genetic defects associated with subjects with the disease, we performed molecular analyses of the SRY gene in DNA from blood leukocytes and gonadal tissue in 12 true hermaphrodites with different karyotypes. Our results using PCR and FISH analyses reveal the presence of hidden mosaicism for SRY or other Y sequences in some patients with XX true hermaphroditism and confirms that mosaicism for SRY limited to the gonads is an alternative mechanism for testicular development in 46,XX true hermaphrodites.     

Molecular analysis of the sex-determining region from the Y chromosome in two patients with Frasier syndrome.

In the Frasier syndrome there is an association between XY gonadal dysgenesis and chronic renal failure. Owing to an observed sex reversal, the Y chromosomes of two girls with this syndrome have been analyzed. Using molecular-biology techniques, no major alterations of the known sex-determining area of the Y chromosome were found. Furthermore, the sequence did not reveal impairment of the recently described testis-determining factor SRY. These data suggest that in the Frasier syndrome, XY sex reversal and renal failure could be the result of either faulty gene(s) located downstream in the sex differentiation pathway during embryogenesis, or impaired SRY regulation. Preliminary results on the Wilms' tumor suppressor gene WT1, a candidate for acting downstream to SRY, are also provided.