Familial frameshift SRY mutation inherited from a mosaic father with testicular dysgenesis syndrome

Molecular and Functional Characterization of Human Sex-Determining Region on the Y Chromosome Variants Using Protamine 1 Promoter

The male sex-determining gene, sex-determining region on the Y chromosome (SRY), is expressed in adult testicular germ cells; however, its role in regulating spermatogenesis remains unclear. The role of SRY in the postmeiotic gene expression was investigated by determining the effect of SRY on the promoter of the haploid-specific Protamine 1 (PRM1) gene, which harbors five distinct SRY-binding motifs. In a luciferase reporter assay system, SRY upregulates PRM1 promoter activity in vitro in a dose-dependent manner. Through a gel-shift assay involving a 31-bp DNA fragment encompassing the SRY element within the PRM1 promoter, the third SRY-binding site on the sense strand (-373/-367) was identified as crucial for PRM1 promoter activation. This assay was extended to analyze 9 SRY variants found in the testicular DNA of 44 azoospermia patients. The findings suggest that SRY regulates PRM1 promoter activity by directly binding to its specific motif within the PRM1 promoter.

Towards improved genetic diagnosis of human differences of sex development

Despite being collectively among the most frequent congenital developmental conditions worldwide, differences of sex development (DSD) lack recognition and research funding. As a result, what constitutes optimal management remains uncertain. Identification of the individual conditions under the DSD umbrella is challenging and molecular genetic diagnosis is frequently not achieved, which has psychosocial and health-related repercussions for patients and their families. New genomic approaches have the potential to resolve this impasse through better detection of protein-coding variants and ascertainment of under-recognized aetiology, such as mosaic, structural, non-coding or epigenetic variants. Ultimately, it is hoped that better outcomes data, improved understanding of the molecular causes and greater public awareness will bring an end to the stigma often associated with DSD.

Etiology of Hypospadias: A Comparative Review of Genetic Factors and Developmental Processes Between Human and Animal Models

Hypospadias is a congenital anomaly of the penis with an occurrence of approximately 1 in 200 boys, but the etiology of the majority of hypospadias has remained unknown. Numerous genes have been reported as having variants in hypospadias patients, and many studies on genetic deletion of key genes in mouse genital development have also been published. Until now, no comparative analysis in the genes related literature has been reported. The basic knowledge of penile development and hypospadias is mainly obtained from animal model studies. Understanding of the differences and similarities between human and animal models is crucial for studies of hypospadias. In this review, mutations and polymorphisms of hypospadias-related genes have been compared between humans and mice, and differential genotype–phenotype relationships of certain genes between humans and mice have been discussed using the data available in PubMed and MGI online databases, and our analysis only revealed mutations in seven out of 43 human hypospadias related genes which have been reported to show similar phenotypes in mutant mice. The differences and similarities in the processes of penile development and hypospadias malformation among human and commonly used animal models suggest that the guinea pig may be a good model to study the mechanism of human penile development and etiology of hypospadias.

Inherited Missense Mutation Occurring in Arginine76 of the SRY Gene Does Not Account for Familial 46, XY Sex Reversal

BACKGROUND

SRY (sex determining region of Y) is one of the important genes involved in the process of human sex determination. The disturbed sex determination caused by an SRY mutation accounts for 10% to 15% of cases with 46, XY sex reversal. Recently, 3 distal enhancers were identified upstream of the SOX9 gene.

OBJECTIVES

The purpose of this study was to investigate the molecular etiology of 46, XY sex reversal in 3 familial patients and a sporadic patient.

DESIGN

Next-generation sequencing was used to reveal the genotype and inherited pattern. Copy number variations and single nucleotide polymorphism haplotyping were analyzed to observe the alteration of enhancers of SOX9. Transcriptional activity of SRY mutation were assessed by a dual luciferase reporting system, and nuclear translocation was observed by confocal microscopy.

RESULTS

Two novel SRY gene mutations, p.Arg76Leu and p.Glu89flx15, were identified. In the pedigree with multiple patients, p.Arg76Leu mutation in SRY and p.Gly212Ser mutation in NR5A1 were identified in the proband. The heterozygous deletion far upstream of the SOX9 gene in chromosome 17 was identified in the 3 patients in this family, containing the distal enhancer eSR-A of SOX9 but not eSR-B and eALDI. The frameshift mutation p.Glu89flx15 was revealed to inhibit the transcriptional activity of the target gene, whereas the missense mutation p.Arg76Leu barely showed an effect.

CONCLUSION

In contrast to sporadic cases, inherited single nucleotide variations of SRY are not the main cause of the severe phenotype of 46, XY sex reversal, and the enhancers of SOX9 should be investigated carefully in such patients.

Novel pathogenic mutations in disorders of sex development associated genes cause 46,XY complete gonadal dysgenesis

Disorders of sex development (DSDs) are congenital conditions in which chromosomal, gonadal and sex is atypical. It is difficult to diagnose and manage patients with DSD in clinical practice, and the molecular etiology of DSD is still not completely understood. Here, we identified two novel pathogenic mutations from three unrelated Chinese patients with 46,XY complete gonadal dysgenesis (CGD) that is a clinical subgroup of DSD by whole exome sequencing. A novel mutation in the SRY gene (c.161delG) was identified in the first patient, and the second patient carried a novel missense mutation in the MAP3K1 gene (c.2117T>G). Bioinformatics analysis found that the deletion of SRY (c.161delG) led to a premature stop codon at amino acid 59 in the SRY protein, which resulted in lacking the DNA binding domain of SRY protein. Functional studies found that the missense mutation in the MAP3K1 gene (c.2117T>G) could interfere with the gene function through increasing the phosphorylation of the downstream targets of MAP3K1, ERK1/2 and p38, which resulted in reducing testis-determining factor SOX9 expression and increasing ovary-promoting factor β-catenin activity. According to the American college of medical genetics and genomics (ACMG) standards and guidelines, these mutations were categorized as "pathogenic" mutations. Thus, our findings provide two novel pathogenic mutations associated with 46,XY CGD that can improve the etiological diagnosis for 46,XY CGD. ABBREVIATIONS.

Novel mosaic SRY gene deletions in three newborn males with variable genitourinary malformations

Ambiguous genitalia in the newborn can present a diagnostic challenge in medical practice. In most cases, the causes of genitourinary anomalies are not well understood; both genetic and environmental factors are thought to play a role. In this study, we report mosaic SRY gene deletion identified by fluorescence in situ hybridization (FISH) analysis in three unrelated newborn male patients with genital anomalies. G-banded chromosomes and microarray analysis were normal for all three patients. One patient had microphallus, hypospadias, bifid scrotum, exstrophic perineal tissue identified as a rectal duplication, lumbar vertebral anomalies, scoliosis, and a dysmorphic sacrum. The other two patients had isolated epispadias with the urethral meatus close to the penopubic junction. All three had bilateral palpable gonads in the scrotum. While this is the first report of mosaic SRY deletions, mosaic SRY sequence variants have been described in patients with variable genitourinary anomalies. This study identifies FISH analysis as a reliable method for mosaic SRY deletion detection. We suggest SRY FISH analysis should be used in the clinical workup of patients with genitourinary ambiguity.

A Brief Review of the Link between Environment and Male Reproductive Health: Lessons from Studies of Testicular Germ Cell Cancer

During the past few decades there has been a significantly increasing trend in germ cell tumours all over the world, particularly in countries with Caucasian populations. The changes in incidence have occurred so fast that only environmental factors can explain this development. This review focuses on the hypothesis that testicular germ cell cancer, which originates from germ cell neoplasia in situ, is of foetal origin and associated with other male reproductive problems through a testicular dysgenesis syndrome, also including foetal origin of impaired spermatogenesis, hypospadias and cryptorchidism. There is little doubt that environmental factors associated with modern lifestyles have - in a broad sense - had an adverse influence on male reproductive health. The hypothesis that exposure to endocrine-disrupting chemicals plays a fundamental role in this trend is plausible. This is based on evidence from animal studies that demonstrate adverse reproductive effects caused by a number of endocrine-disrupting chemicals to which humans are exposed as part of our modern lifestyle.

The biology of germ cell tumors in disorders of sex development

Development of a malignant germ cell tumor, i.e., germ cell cancer (GCC) in individuals with disorders of sex development (DSD) depends on a number of (epi-)genetic factors related to early gonadal- and germ cell development, possibly related to genetic susceptibility. Fetal development of germ cells is orchestrated by strict processes involving specification, migration and the development of a proper gonadal niche. In this review we will discuss the early (epi-)genetic events in normal and aberrant germ cell and gonadal development. Focus will be on the formation of the precursor lesions of GCC in individuals who have DSD. In our view, expression of the different embryonic markers in, and epigenetic profile of the precursor lesions reflects the developmental stage in which these cells are blocked in their maturation. Therefore, these are not a primary pathogenetic driving force. Progression later in life towards a full blown cancer likely depends on additional factors such as a changed endocrine environment in a susceptible individual. Genetic susceptibility is, as evidenced by the presence of specific risk genetic variants (SNPs) in patients with a testicular GCC, related to genes involved in early germ cell and gonadal development.

Clinical, genetic, biochemical, and testicular biopsy findings among 1,213 men evaluated for infertility

OBJECTIVE

To study the pathologic findings among men evaluated for infertility.

DESIGN

A retrospective, single-center, cross-sectional study.

SETTING

University hospital-based research center.

PARTICIPANT(S)

We included data from 1,213 medical records from infertile men referred for diagnostic work-up from 2005 to 2009.

INTERVENTIONS(S)

None.

MAIN OUTCOME MEASURE(S)

Health history, clinical findings, chromosome/genetic aberrations, semen quality, reproductive hormones.

RESULT(S)

In total, 64.4% of the infertile men had one or more reproductive disorders or factors influencing fertility, leaving 35.6% diagnosed as idiopathic infertile. In 244 patients (20%), including seven cases of testicular cancer and/or germ cell neoplasia in situ, a pathologic finding was first detected during diagnostic work-up. Two hundred four patients (16.8%) had a history of cryptorchidism and 154 (12.7%) of varicocele (grade 2 and 3). Thirty-three patients had chromosomal abnormalities, including 16 with sex chromosome abnormalities (11 with 47,XXY). Y-chromosome microdeletions were detected in 65 patients (5.4%). One hundred thirty-three had azoospermia, of which 58 had testicular biopsy findings (Sertoli cell-only syndrome: n = 23; spermatogenic arrest: n = 7; impaired spermatogenesis and atrophy: n = 28). Additionally, in idiopathic infertile men and infertile men with additional symptoms of testicular dysgenesis syndrome, 22.5% presented with a degree of Leydig cell insufficiency, with the highest frequency (33.1%) among patients with sperm concentration <5 million/mL.

CONCLUSION(S)

We report pathologic findings that could explain the male-factor infertility in two-thirds of infertile men referred to our center. Thus, male infertility may be a sign of an underlying disease that warrants attention.

Copy Number Variations of the Azoospermia Factor Region and SRY Are Not Associated with the Risk of Hypospadias

We investigated the frequency of copy number variations (CNVs) in the Y chromosome of Japanese children with hypospadias. We analyzed the copy number of the azoospermia factor (AZF) region and SRY, using multiplex ligation-dependent probe amplification. Four AZF-linked CNVs, including one novel simple duplication, were identified in 39 of 89 patients, at a frequency comparable to that of those in unaffected individuals. SRY-linked CNVs were absent in our patients. The results imply that CNVs in the AZF region and SRY are not associated with the risk of hypospadias in the Japanese population, although the pathogenicity of the AZF-linked simple duplication remains to be elucidated.

Possible fetal determinants of male infertility

Although common reproductive problems, such as male infertility and testicular cancer, present in adult life, strong evidence exists that these reproductive disorders might have a fetal origin. The evidence is derived not only from large epidemiological studies that show birth-cohort effects with regard to testicular cancer, levels of testosterone and semen quality, but also from histopathological observations. Many infertile men have histological signs of testicular dysgenesis, including Sertoli-cell-only tubules, immature undifferentiated Sertoli cells, microliths and Leydig cell nodules. The most severe gonadal symptoms occur in patients with disorders of sexual development (DSDs) who have genetic mutations, in whom even sex reversal of individuals with a 46,XY DSD can occur. However, patients with severe DSDs might represent only a small proportion of DSD cases, with milder forms of testicular dysgenesis potentially induced by exposure to environmental and lifestyle factors. Interestingly, maternal smoking during pregnancy has a stronger effect on spermatogenesis than a man's own smoking. Other lifestyle factors such as alcohol consumption and obesity might also have a role. However, increasing indirect evidence exists that exposure to ubiquitous endocrine disrupting chemicals, present at measurable concentrations in individuals, might affect development of human fetal testis. If confirmed, health policies to prevent male reproductive problems should not only target adult men, but also pregnant women and their children.

Identification of a novel androgen receptor mutation in a family with multiple components compatible with the testicular dysgenesis syndrome

CONTEXT

Androgen signaling via the androgen receptor (AR) is essential for normal testis development and male reproductive functions. We describe a rare family with 3 males affected by a mild disorder of sex determination compatible with testicular dysgenesis syndrome (TDS), including subfertility, cryptorchidism, hypospadias, and testicular cancer, caused by a novel AR mutation.

OBJECTIVE

The aim of this study was to describe the phenotype of the affected males, characterize functionally the novel AR mutation, and discuss the significance of partial androgen insufficiency in the pathogenesis of TDS.

PARTICIPANTS

The proband, his first cousin, and a nephew underwent a detailed clinical investigation including genetic tests, whereas four female members of the family were tested for the specific AR mutation.

RESULTS

A novel AR mutation, c.2214T>G;p.Ile738Met, was identified in the affected family members. Functional analysis of the mutation in a gene-reporter assay showed a 50% reduction in AR-induced transcriptional activity. The affected males had elevated LH and T in accordance with decreased AR signaling. The histology and immunohistochemical profile of the testis tissue from the 2 patients with testicular cancer showed features consistent with insufficient testis development and TDS.

CONCLUSION

The presence of all hallmarks of TDS, including germ cell cancer, in a family with a novel AR mutation causing a partial decrease in AR function is in line with the concept that reduced androgen signaling may contribute to the development of TDS. It also seems consistent with the hypothesis that environmental factors interfering with this pathway can play a role in the pathogenesis of TDS.

Disorders of sex development: summaries of long-term outcome studies

Existing outcomes for DSD individuals are inadequate because reports are based upon information collected retrospectively. This paper is presented to review existing data emphasizing information needed to lead to better future care, is based on presentations and discussions at a multi-disciplinary meeting on DSD held in Annecy in 2012, and is not intended to define the present status of management of each of the various DSD diagnoses. Rather it is intended to provide information needed to do studies regarding outcome data from the treatment of children with DSD by providing a summary of recommendations of 'patient-centered' topics that need investigation. The hope is that by being concerned with what is not known, new protocols will be developed for improving both early management and transition to adult life.

SRY mutation analysis by next generation (deep) sequencing in a cohort of chromosomal Disorders of Sex Development (DSD) patients with a mosaic karyotype

Background

The presence of the Y-chromosome or Y chromosome-derived material is seen in 4-60% of Turner syndrome patients (Chromosomal Disorders of Sex Development (DSD)). DSD patients with specific Y-chromosomal material in their karyotype, the GonadoBlastoma on the Y-chromosome (GBY) region, have an increased risk of developing type II germ cell tumors/cancer (GCC), most likely related to TSPY. The Sex determining Region on the Y gene (SRY) is located on the short arm of the Y-chromosome and is the crucial switch that initiates testis determination and subsequent male development. Mutations in this gene are responsible for sex reversal in approximately 10-15% of 46,XY pure gonadal dysgenesis (46,XY DSD) cases. The majority of the mutations described are located in the central HMG domain, which is involved in the binding and bending of the DNA and harbors two nuclear localization signals. SRY mutations have also been found in a small number of patients with a 45,X/46,XY karyotype and might play a role in the maldevelopment of the gonads.

Methods

To thoroughly investigate the presence of possible SRY gene mutations in mosaic DSD patients, we performed next generation (deep) sequencing on the genomic DNA of fourteen independent patients (twelve 45,X/46,XY, one 45,X/46,XX/46,XY, and one 46,XX/46,XY).

Results and conclusions

The results demonstrate that aberrations in SRY are rare in mosaic DSD patients and therefore do not play a significant role in the etiology of the disease.

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.

46, XY gonadal dysgenesis: new SRY point mutation in two siblings with paternal germ line mosaicism

Familial recurrence risks are poorly understood in cases of de novo mutations. In the event of parental germ line mosaicism, recurrence risks can be higher than generally appreciated, with implications for genetic counseling and clinical practice. In the course of treating a female with pubertal delay and hypergonadotropic hypogonadism, we identified a new missense mutation in the SRY gene, leading to somatic feminization of this karyotypically normal XY individual. We tested a younger sister despite a normal onset of puberty, who also possessed an XY karyotype and the same SRY mutation. Imaging studies in the sister revealed an ovarian tumor, which was removed. DNA from the father's blood possessed the wild type SRY sequence, and paternity testing was consistent with the given family structure. A brother was 46, XY with a wild type SRY sequence strongly suggesting paternal Y-chromosome germline mosaicism for the mutation. In disorders of sexual development (DSDs), early diagnosis is critical for optimal psychological development of the affected patients. In this case, preventive karyotypic screening allowed early diagnosis of a gonadal tumor in the sibling prior to the age of normal puberty. Our results suggest that cytological or molecular diagnosis should be applied for siblings of an affected DSD individual.

Delayed Recognition of Disorders of Sex Development (DSD): A Missed Opportunity for Early Diagnosis of Malignant Germ Cell Tumors

Disorders of sex development (DSD) are defined as a congenital condition in which development of chromosomal, gonadal or anatomical sex is atypical. DSD patients with gonadal dysgenesis or hypovirilization, containing part of the Y chromosome (GBY), have an increased risk for malignant type II germ cell tumors (GCTs: seminomas and nonseminomas). DSD may be diagnosed in newborns (e.g., ambiguous genitalia), or later in life, even at or after puberty. Here we describe three independent male patients with a GCT; two were retrospectively recognized as DSD, based on the histological identification of both carcinoma in situ and gonadoblastoma in a single gonad as the cancer precursor. Hypospadias and cryptorchidism in their history are consistent with this conclusion. The power of recognition of these parameters is demonstrated by the third patient, in which the precursor lesion was diagnosed before progression to invasiveness. Early recognition based on these clinical parameters could have prevented development of (metastatic) cancer, to be treated by systemic therapy. All three patients showed a normal male 46,XY karyotype, without obvious genetic rearrangements by high-resolution whole-genome copy number analysis. These cases demonstrate overlap between DSD and the so-called testicular dysgenesis syndrome (TDS), of significant relevance for identification of individuals at increased risk for development of a malignant GCT.

Mammalian testis-determining factor SRY and the enigma of inherited human sex reversal: frustrated induced fit in a bent protein-DNA complex

Mammalian testis-determining factor SRY contains a high mobility group box, a conserved eukaryotic motif of DNA bending. Mutations in SRY cause XY gonadal dysgenesis and somatic sex reversal. Although such mutations usually arise de novo in spermatogenesis, some are inherited and so specify male development in one genetic background (the father) but not another (the daughter). Here, we describe the biophysical properties of a representative inherited mutation, V60L, within the minor wing of the L-shaped domain (box position 5). Although the stability and DNA binding properties of the mutant domain are similar to those of wild type, studies of SRY-induced DNA bending by subnanosecond time-resolved fluorescence resonance energy transfer (FRET) revealed enhanced conformational fluctuations leading to long range variation in bend angle. (1)H NMR studies of the variant protein-DNA complex demonstrated only local perturbations near the mutation site. Because the minor wing of SRY folds on DNA binding, the inherited mutation presumably hinders induced fit. Stopped-flow FRET studies indicated that such frustrated packing leads to accelerated dissociation of the bent complex. Studies of SRY-directed transcriptional regulation in an embryonic gonadal cell line demonstrated partial activation of downstream target Sox9. Our results have demonstrated a nonlocal coupling between DNA-directed protein folding and protein-directed DNA bending. Perturbation of this coupling is associated with a genetic switch poised at the threshold of activity.

Dissecting the molecular pathways of (testicular) germ cell tumour pathogenesis; from initiation to treatment-resistance

Human type II germ cell tumours (GCTs) originate from an embryonic germ cell, either as a primordial germ cell or gonocyte. This start determines the biological as well as clinical characteristics of this type of cancer, amongst others their totipotency as well as their overall (exceptional) sensitivity to DNA damaging agents. The histology of the precursor lesion, either carcinoma in situ or gonadoblastoma, depends on the level of testicularization (i.e. testis formation) of the gonad. The impact of either intrinsic (genetic) - and environmental factors involved in the pathogenesis is demonstrated by disorders of sex development as well as testicular dysgenesis syndrome as risk factors, including cryptorchidism, hypospadias and disturbed fertility as parameters. This knowledge allows identification of individuals at risk for development of this type of cancer, being a population of interest for screening. Factors known to regulate pluripotency during embryogenesis are proven to be of diagnostic value for type II GCTs, including OCT3/4, even applicable for non-invasive screening. In addition, presence of stem cell factor, also known as KITLG, allows distinction between delayed matured germ cells and the earliest stages of malignant transformation. This is of special interest because of the identified association between development of type II GCTs of the testis and a limited number of single nucleotide polymorphisms, including some likely related to KITL. Transition from the precursor lesion to an invasive cancer is associated with gain of the short arm of chromosome 12, in which multiple genes might be involved, including KRAS2 and possibly NANOG (pseudogenes). While most precursor lesions will progress to an invasive cancer, only a limited number of cancers will develop treatment resistance. Putative explanatory mechanisms are identified, including presence of microsatellite instability, BRAF mutations, apoptosis suppression and p21 sub-cellular localization. It remains to be investigated how these different pathways integrate to each other and how informative they are at the patient-individual level. Further understanding will allow development of more targeted treatment, which will benefit quality of life of these young cancer patients.

Identification of novel SRY mutations and SF1 (NR5A1) changes in patients with pure gonadal dysgenesis and 46,XY karyotype

Primary amenorrhea due to 46,XY disorders of sexual development (DSD) is complex with the involvement of several genes. Karyotyping of such patients is important as they may develop dysgerminoma and molecular analysis is important to identify the underlying mechanism and explore the cascade of events occurring during sexual development. The present study was undertaken for the genetic analysis in seven patients from five families presenting with primary amenorrhea and diagnosed with pure gonadal dysgenesis. Karyotyping was done and the patients were screened for underlying changes in SRY, desert hedgehog (DHH), DAX1 (NR0B1) and SF1 (NR5A1) genes, mutations in which are implicated in DSD. All the patients had 46,XY karyotype and two novel SRY mutations were found. In Family 1 (Patient S1.1) a missense mutation c.294G>A was seen, which results in a stop codon at the corresponding amino acid (Trp98X) and in Family 2 (Patients S2.1, S2.2 and S2.3), a missense mutation c.334G>A (Glu112Leu) was identified in all affected sisters. Both mutations were seen to occur in the conserved high mobility group box of SRY gene. One heterozygous change c.427G>A resulting in Glu143Lys in DHH gene in one patient and two heterozygous changes in the intronic region of SF1 (NR5A1) gene (c.244+80G>A+ c.1068-20C>T) in another patient were noted. One individual did not show changes in any of the genes analyzed. These results reiterate the importance of SRY and others, such as SF1 (NR5A1) and DHH, that are involved in the cascade of events leading to sex determination and also their role in sex reversal.

A SRY-HMG box frame shift mutation inherited from a mosaic father with a mild form of testicular dysgenesis syndrome in Turner syndrome patient

Background

Sex determining factor (SRY) located on the short arm of the Y chromosome, plays an important role in initiating male sex determination, resulting in development of testicular tissue. Presence of the SRY gene in females results in XY sex reversal and increased risk of gonadal germ cell tumours if the karyotype also includes the so-called GonadoBlastoma on the Y chromosome (GBY) region. The majority of mutations within the SRY gene are de novo affecting only a single individual in the family. The mutations within the high-mobility group (HMG) region have the potential to affect its DNA binding activity.

Case Presentation

We performed G- and R-banding cytogenetic analysis of the patient and her family members including her father. We also performed molecular genetic analysis of SRY gene. Cytogenetic analysis in the patient (Turner Syndrome) revealed the mosaic karyotype as 45, X/46, XY (79%/21% respectively) while her father (milder features with testicular dysgenesis syndrome) has a normal male karyotype (46, XY). Using molecular approach, we screened the patient and her father for mutations in the SRY gene. Both patient and her father showed the same deletion of cytosine within HMG box resulting in frame shift mutation (L94fsX180), the father in a mosaic pattern. Histological examination of the gonads from the patient revealed the presence of gonadoblastoma formation, while the father presented with oligoasthenozoospermia and a testicular seminoma. The frameshift mutation at this codon is novel, and may result in a mutated SRY protein.

Conclusion

Our results suggest that lack of a second sex chromosome in majority cells of the patient may have triggered the short stature and primary infertility, and the mutated SRY protein may be associated with the development of gonadoblastoma. It is of importance to note that mosaic patients without a SRY mutation also have a risk for malignant germ cell tumors.