Frasier Syndrome Research Articles

Recurrence of a dysgerminoma in Frasier syndrome

FS is an inherited disease characterized by male pseudohermaphroditism and glomerular involvement leading to end-stage renal disease during adolescence or early adulthood (J Pediatr 1964:64:740). The FS phenotype in 46,XY patients consists of female external genitalia, gonadal dysgenesis, high risk of gonadoblastoma, and development of renal failure in the second decade of life. FS is caused by heterozygous mutation in intron 9 of the WT1 leading to a change in splicing that results in loss of three amino acids (+KTS isoform), thus disrupting the normal ratio of the +KTS/-KTS isoforms that is critical for proper gonadal and renal development (Nat Genet 1997:17:467; Hum Mol Genet 1998:7:709). We report on a patient followed for FS revealed by acute peritoneal syndrome because of ovarian dysgerminoma. Therapeutic options had led to an unusual course with recurrent neoplastic disease after renal transplantation.

Pituitary Origin as the Cause of Persistently Elevated Human Chorionic Gonadotropin in an Adolescent With Primary Amenorrhea Secondary to Frasier Syndrome

We report a female adolescent with Frasier syndrome (46 XY gonadal dysgenesis with focal segmental glomerulosclerosis-FSGS) who presented with primary amenorrhea and was found to have persistently elevated levels of hCG, status post bilateral gonadectomy, beyond ranges reported in postmenopausal women (beta hCG < 14 mIU/ml). The purpose of this case report is to alert clinicians to include a pituitary source of hCG in the differential diagnosis within this patient population.

Genotype/Phenotype Correlation in Nephrotic Syndrome Caused by WT1 Mutations

The risk of developing Wilms tumor (WT) can be present or absent in patients with nephrotic syndrome (NS) caused by WT1 mutations. Here, the genotype/phenotype correlation regarding the outcome and risk for WT in 52 patients from 51 families with NS due to WT1 mutations is described. This study followed 19 patients with mutations in intron 9 splice donor site (KTS mutations), 27 patients with missense mutations, 4 patients with nonsense mutations, 1 patient with a splice site mutation in intron 8, and 1 patient with a deletion. Twenty-four different WT1 mutations were detected. Sixteen of the 19 patients with KTS mutations were females. These patients had isolated NS if karyotype was 46,XX and Frasier syndrome if karyotype was 46,XY. Patients with KTS mutations presented at a significantly older age and with a slower progression toward chronic kidney disease (CKD) stage 5, compared with missense mutations. Patients with nonsense mutations presented initially with WT. Six patients with missense mutations developed WT after the diagnosis of NS (interval-range from NS onset to WT of 0.1 to 1.4 years). (1) KTS mutations cause isolated NS with absence of WT in 46,XX females. (2) KTS mutations cause Frasier syndrome with gonadoblastoma risk in 46,XY phenotypic females. (3) KTS mutations cause NS with a slower progression when compared with missense mutations. (4) Missense mutations can occur with and without WT. (5) WT1 analysis is important in young patients with NS for early detection and tumor prophylaxis.

A female infant with Frasier syndrome showing splice site mutation in Wilms’ tumor gene (WT1) intron 9

Wilms' tumor gene (WT1) abnormality leads to various disorders of differentiation as well as renal and urinary system abnormalities. Here we present a case of WT1 abnormality and steroid-resistant nephrotic syndrome in a female infant. The 3-year-old patient was initially diagnosed with proteinuria at an annual mass screening program for children aged three years and was referred to our hospital. She met the diagnostic criteria for nephrotic syndrome and showed normal renal function. The patient was treated with corticosteroids; however her condition showed resistance to corticosteroids. On renal biopsy, she was diagnosed with focal segmental glomerulosclerosis (FSGS). Because of the possibility of WT1 abnormality, an exon array analysis was conducted, which ruled out Denys-Drash Syndrome (DDS). The patient was then diagnosed with Frasier Syndrome (FS) on the basis of donor site mutation (IVS9+5G > A) of the splice site in the intron 9. Reports of female infants with FS are extremely rare. FS is one of the pre-mRNA splicing diseases, in which the occurrence of symptoms is associated with a decrease in the ratio of the lysine-threonine-serine (+/- KTS) isoform of the WT1 protein. A typical case exhibits 46 XY male karyotype and is characterized by male pseudohermaphroditism with cord-like gonadal structures as well as progressive nephropathy caused by FSGS. However, in female infants without such extrarenal signs, it is necessary to consider the analysis for WT1 intron 9 for conclusive diagnosis of FS, because the presence of nephropathy is the only symptom for possible detection.

Frasier syndrome: early gonadoblastoma and cyclosporine responsiveness

Frasier syndrome is characterized by progressive glomerulopathy that is unresponsive to corticosteroids, male pseudohermaphroditism, and an increased risk of genitourinary tumors. Of 21 girls with steroid-resistant nephrotic syndrome secondary to focal segmental glomerulosclerosis (FSGS) who were screened for mutations in the WT1 gene, two showed Frasier syndrome. Both patients had donor splice-site mutations in intron 9 of the WT1 gene and a male karyotype (46, XY). Long-term therapy with cyclosporine resulted in partial remission in both cases. One patient showed foci of gonadoblastoma in the excised dysgenetic gonads. This report highlights the need for screening for mutations in the WT1 gene in girls with steroid-resistant FSGS. Patients with Frasier syndrome might benefit from early gonadectomy.

A Novel WT1 Gene Mutation in a Three-Generation Family with Progressive Isolated Focal Segmental Glomerulosclerosis

Wilms tumor-suppressor gene-1 (WT1) plays a key role in kidney development and function. WT1 mutations usually occur in exons 8 and 9 and are associated with Denys-Drash, or in intron 9 and are associated with Frasier syndrome. However, overlapping clinical and molecular features have been reported. Few familial cases have been described, with intrafamilial variability. Sporadic cases of WT1 mutations in isolated diffuse mesangial sclerosis or focal segmental glomerulosclerosis have also been reported. Molecular analysis of WT1 exons 8 and 9 was carried out in five members on three generations of a family with late-onset isolated proteinuria. The effect of the detected amino acid substitution on WT1 protein's structure was studied by bioinformatics tools. Three family members reached end-stage renal disease in full adulthood. None had genital abnormalities or Wilms tumor. Histologic analysis in two subjects revealed focal segmental glomerulosclerosis. The novel sequence variant c.1208G>A in WT1 exon 9 was identified in all of the affected members of the family. The lack of Wilms tumor or other related phenotypes suggests the expansion of WT1 gene analysis in patients with focal segmental glomerulosclerosis, regardless of age or presence of typical Denys-Drash or Frasier syndrome clinical features. Structural analysis of the mutated protein revealed that the mutation hampers zinc finger-DNA interactions, impairing target gene transcription. This finding opens up new issues about WT1 function in the maintenance of the complex gene network that regulates normal podocyte function.

Frasier syndrome, a potential cause of end-stage renal failure in childhood

The diagnosis of Frasier syndrome is based on the association of male pseudohermaphroditism (as a result of gonadal dysgenesis), with steroid-resistant nephrotic syndrome due to focal and segmental glomerular sclerosis (FSGS), which progresses to end-stage renal failure (ESRF) during adolescence or adulthood. Frasier syndrome results from mutations in the Wilms' tumour suppressor gene WT1, which is responsible for alterations in male genital development and podocyte dysfunction. We describe the case of a 7-year-old girl who was referred to the paediatric emergency department with ESRF. Haemodialysis was started immediately because of severe hypertension and hyperkalaemia. In view of the fact that our patient had a past medical history of pseudohermaphroditism, we suspected that the acute presentation in ESRF may be related to a new diagnosis of Frasier syndrome. Our hypothesis was confirmed on examination of the medical records. There had been no medical follow-up for several years and, in particular, no renal imaging or functional assessment had ever been performed. This lack of surveillance explains why our patient presented with ESRF much earlier in this disease than expected and subsequently had to undergo kidney transplantation at a very young age.

Bilateral gonadoblastoma with dysgerminoma and pilocytic astrocytoma with WT1 GT‐IVS9 mutation: A 46 XY phenotypic female with Frasier syndrome

Frasier syndrome is characterized by a 46 XY disorder of sex development, nephropathy, and increased risk for gonadoblastoma due to Wilms tumor 1(WT1) mutation in the donor splice site of intron-9, resulting in the splice form +KTS. Germ cell tumors and gonadoblastomas have been reported previously in Frasier syndrome. We present the clinical, radiological, and genetic (WT1 mutation analysis) of a 46 XY phenotypic female with Frasier syndrome with bilateral gonadoblastoma with dysgerminoma who developed pilocytic astrocytoma.

A cell-autonomous role for WT1 in regulating Sry in vivo

Human patients with Frasier syndrome express reduced levels of the +KTS isoforms of the developmental regulator WT1 and exhibit complete XY gonadal dysgenesis and male-to-female sex reversal. Mice with a targeted mutation that blocks production of these isoforms show a reduction in Sry mRNA in the gonad, but the molecular and cellular basis of this reduction has not been established. Using immunofluorescence analysis, we found a significantly lower level of SRY protein per cell in XY Wt1(+KTS)-null mouse gonads. We also found a reduced number of SRY-expressing cells, correlating with a decrease in cell proliferation at and near the coelomic epithelium at 11.5 dpc. No reduction in somatic cell numbers was seen in XX Wt1(+KTS)-null gonads, indicating that the effect of WT1 on cell proliferation is mediated by Sry. Sertoli cell differentiation was blocked in XY Wt1(+KTS)-null mouse gonads, as indicated by the loss of SOX9 and Fgf9 expression, but the addition of recombinant FGF9 to ex vivo gonad cultures rescued the mutant phenotype, as indicated by the induction of the Sertoli-cell specific marker anti-Müllerian hormone. Our data suggest that WT1(+KTS) is involved in the cell-autonomous regulation of Sry expression, which in turn influences cell proliferation and Sertoli cell differentiation via FGF9. Thus, sex reversal in Wt1(+KTS)-null mice and Frasier syndrome patients results from a failure of Sertoli cells both to fully differentiate and to reach sufficient numbers to direct testis development.

Evolutive study of children with diffuse mesangial sclerosis

Diffuse mesangial sclerosis (DMS) is a renal disease that usually presents as a nephrotic syndrome. It is characterized by early onset and rapid progression to end-stage renal disease, and can occur as an isolated finding or as part of the Denys-Drash syndrome. The aim of this study was to characterize clinical features and outcomes of DMS in a cohort of children. We retrospectively analyzed all cases of DMS diagnosed in our hospital between 1973 and 2008 and evaluated the progression of the disease in relation to different variables. We studied 14 patients, four with incomplete Denys-Drash syndrome and one with Frasier syndrome. All patients developed renal failure. Eight patients received a renal transplant with no relapse of the disease. Bilateral nephrectomy was performed in nine patients with end-stage renal disease. Seven patients died, with sepsis being the main cause of death. Diffuse mesangial sclerosis must be suspected in a child that presents with early onset proteinuria and/or rapidly progressive renal failure. Karyotype and WT1 gene analysis should be performed because of the predisposition of patients to develop different types of tumors. This nephropathy has a poor prognosis, but the survival rate has improved in the last decade.

Clinical and genetic findings of five patients with WT1-related disorders

To present phenotypic variability of WT1-related disorders. Description of clinical and genetic features of five 46,XY patients with WT1 anomalies. Patient 1: newborn with genital ambiguity; he developed Wilms tumor (WT) and chronic renal disease and died at the age of 10 months; the heterozygous 1186G>A mutation compatible with Denys-Drash syndrome was detected in this child. Patients 2 and 3: adolescents with chronic renal disease, primary amenorrhea and hypergonadotrophic hypogonadism; patient 2 had a gonadoblastoma. The heterozygous IVS9+4, C>T mutation, compatible with Frasier syndrome was detected. Patient 4: 9-year-old boy with aniridia, genital ambiguity, dysmorphisms and mental deficiency; a heterozygous 11p deletion, compatible with WAGR syndrome was detected. Patient 5: 2 months old, same diagnosis of patient 4; he developed WT at the age of 8 months. Constitutional abnormalities of WT1 cause gonadal and renal anomalies and predisposition to neoplasia and must be investigated in patients with ambiguous genitalia, chronic renal disease and(or) Wilms tumors; primary amenorrhea with chronic renal disease; and aniridia, genital ambiguity and dysmorphisms.

Management of Wilms tumors in Drash and Frasier syndromes

Children with WT1 gene-related disorders such as Denys-Drash syndrome (DDS) and Frasier syndrome (FS) are at increased risk of Wilms tumor and end-stage renal disease. We investigated whether Wilms tumors in these patients displayed a specific phenotype or behavior and whether nephron-sparing surgery was beneficial. We retrospectively studied all patients with DDS, FS, or other WT1 mutations treated at our institutions between 1980 and 2007. We identified 20 patients, of whom 18 had benign or malignant tumors. Wilms tumors occurred in 15 patients, being unilateral in 10 and bilateral in 5 (20 tumors). Median age at Wilms tumor diagnosis was 9 months. No patients had metastases. According to the International Society of Pediatric Oncology Working Classification, there were 19 intermediate-risk tumors and one high-risk tumor; no tumor was anaplastic. In patients with nephropathy who underwent unilateral nephrectomy for Wilms tumor or nephron-sparing surgery for bilateral Wilms tumor, mean time to dialysis was 11 or 9 months, respectively. Other tumors included three gonadoblastomas (in two patients), one retroperitoneal soft-tissue tumor, and one transitional cell papilloma of the bladder. Two patients, both with stage I Wilms tumor, died from end-stage renal disease-related complications. The median follow-up time for the 18 survivors was 136 months (range, 17-224 months). Most Wilms tumors in children with WT1-related disorders were early-stage and intermediate-risk tumors, with a young age at diagnosis. In patients without end-stage renal disease, nephron-sparing surgery should be considered for delaying the onset of renal failure.

A novel Wilms’ tumor 1 gene mutation in a child with severe renal dysfunction and persistent renal blastema

The Wilms' tumor suppressor gene WT1 is an important regulator of development. Mutations in this gene have been associated with Wilms' tumor, Frasier syndrome, and Denys-Drash syndrome, as well as isolated glomerular disease. Here we report the case of a 4-month-old girl, who presented with end-stage renal disease, thrombopenia, anemia, and cardiac hypertrophy accompanied by severe hypertension. Histological analysis of kidney biopsies revealed a massive and diffuse nephroblastomatosis with a dramatic reduction in the number of glomeruli. Although no normal cortical nephrons could be detected, medullary organization was nearly normal. Sequence analysis demonstrated a heterozygous nonsense mutation in exon 9 of WT1, which leads to a truncation of the WT1 protein at the beginning of zinc finger 3. Given the requirement of WT1 for normal development of the kidney and heart, these data raise the hypothesis that the mutation identified was responsible for the severe phenotype observed in our patient.

The ratio of ±KTS splice variants of the Wilms’ tumour suppressor protein WT1 mRNA is determined by an intronic enhancer

Alternative splicing of the primary transcript of the Wilms' tumour suppressor gene WT1 involving 2 overlapping 5' splice sites at the end of exon 9 results in the insertion of 2 amino acids (KTS) between zinc fingers 3 and 4 of the protein. The presence or absence of these 3 amino acids has consequences for DNA binding affinity, protein-protein interactions, and subnuclear localization. Disruption of the characteristic +KTS to -KTS ratio of mRNA isoforms as a result of mutations in the +KTS splice site results in Frasier syndrome. Mutational analysis of a WT1 minigene construct was carried out to search for sequences that regulate the +/-KTS alternative splicing event. A strong pyrimidine-rich intronic enhancer that increases the use of the +KTS splice site was identified. Cross-linking experiments with nuclear extracts demonstrated that this enhancer specifically binds a protein with a molecular mass of 42+/-2 kDa. One candidate for this trans-factor is the splicing regulator TIA-1, which binds to the pyrimidine-rich enhancer in the primary transcript from the minigene construct and increases the +/-KTS splicing ratio. The observation that TIA-1 and WT1 are both involved in apoptosis supports our proposal for a functional link between these proteins.

New insights into the function of the Wilms tumor suppressor geneWT1in podocytes

The Wilms tumor suppressor gene WT1 is essential for early urogenital development: homozygous mutations in WT1 result in embryonic lethality due to a failure in the development of kidneys and gonads. In the adult kidney, WT1 expression is limited to the glomerular podocytes. Several human nephrotic diseases arise from mutations of the WT1 gene, including mutations that affect its zinc-fingers and alternative splicing of +/- KTS isoforms. These include WAGR (for Wilms tumor, aniridia, genitourinary anomalies, and mental retardation), and Frasier and Denys-Drash syndromes. Recent advances including the development of transgenic mouse models and conditionally immortalized podocyte cell lines are beginning to shed light on WT1's crucial role in podocyte function.

Expanding the Clinical Spectrum of Frasier Syndrome

Frasier syndrome is an uncommon genetic disorder featuring progressive glomerulopathy, male pseudohermaphroditism, and gonadal dysgenesis with increased risk of gonadoblastoma and malignant germ cell tumors. It is caused by mutations in the donor splice site in intron 9 of the WT1 gene. However, because of its rarity there is limited literature available on the precise spectrum and recommended treatment modalities of this syndrome. We present the clinicopathological findings in 4 patients: 3 phenotypically female adolescents presenting with proteinuria and primary amenorrhea and a 6-month-old baby girl presenting with nephrotic syndrome in whom this very unusual case of early onset was confirmed by molecular studies. The significance of early recognition of Frasier syndrome and its differentiation from Denys-Drash syndrome is reviewed and discussed. Our observation of a case presenting with early clinical manifestations, in contrast with the classical presentation in adolescence, justifies the expansion of the clinical spectrum of Frasier syndrome and contributes to the understanding and appropriate clinical management of these patients.

Characteristics of testicular dysgenesis syndrome and decreased expression of SRY and SOX9 in Frasier syndrome

Frasier syndrome (FS) is characterized by chronic renal failure in early adulthood, varying degrees of gonadal dysgenesis, and a high risk for gonadal germ cell malignancies, particularly gonadoblastoma. Although it is known to arise from heterozygous splice mutations in intron 9 of the Wilms' tumor gene 1 (WT1), the mechanisms by which these mutations result in gonadal dysgenesis in humans remain obscure. Here we show that a decrease in WT1 + KTS isoforms due to disruption of alternative splicing of the WT1 gene in a FS patient is associated with diminished expression of the transcription factors SRY and SOX9 in Sertoli cells. These findings provide the first confirmation in humans of the results obtained by others in mice. Consequently, Sertoli cells fail to form the specialized environment within the seminiferous tubules that normally houses developing germ cells. Thus, germ cells are unable to fully mature and are blocked at the spermatogonial-spermatocyte stage. Concomitantly, subpopulations of the malignant counterpart of primordial germ cells/gonocytes, the intratubular germ cell neoplasia unclassified type (ITGCN), are identified. Furthermore, dysregulated Leydig cells produce insufficient levels of testosterone, resulting in hypospadias. Collectively, the impaired spermatogenesis, hypospadias and ITGCN comprise part of the developmental disorder known as 'testicular dysgenesis syndrome' (TDS), which arises during early fetal life. The data presented here show that critical levels of WT1 + KTS, SRY and SOX9 are required for normal Sertoli cell maturation, and subsequent normal spermatogenesis. To further study the function of human Sertoli cells in the future, we have established a human cell line.

Complete sex reversal in a WAGR syndrome patient

The WAGR contiguous gene deletion syndrome is a combination of Wilms tumor, aniridia, genitourinary abnormalities, and mental retardation. Children with WAGR syndrome invariably have a constitutional chromosomal deletion at 11p13. WT1 haploinsufficiency is associated with a significant risk of Wilms tumor while PAX6 haploinsufficiency lead to aniridia, both genes located in the deleted region. The 46,XY patients with WAGR syndrome are often born with genital abnormalities such as cryptorchidism or hypospadias but more rarely ambiguous genitalia. To our knowledge, complete sex reversal has never been observed in WAGR syndrome patients. Here, we report on the clinical, cytogenetic, and molecular characterization of a child with WAGR syndrome and complete sex reversal. The young girl had female external and internal genitalia with normal uterus and fallopian tubes while the ovaries were not observed. Chromosomal analysis showed a 46,XY,del(11)(p12p14.1) karyotype. A 1-Mb resolution array CGH experiment estimated the size of the interstitial deletion at approximately 10 Mb encompassing WT1 and PAX6. The entire coding regions of WT1 and SRY have been sequenced and no mutation has been identified. Frasier syndrome (FS) and Denys-Drash syndrome (DDS) are two disorders associated with mutations in the WT1 gene. Complete sex reversal is a feature usually present in FS and sometimes in DDS, but until now never observed in WAGR syndrome. The present report suggests that these conditions may be considered as part of the spectrum of disease due to WT1 gene alterations.

WT1 mutation and podocyte molecular expression in a Chinese Frasier syndrome patient

We report on a Chinese girl with Frasier syndrome (FS). She presented with steroid-resistant focal segmental glomerulosclerosis (FSGS) and male pseudohermaphroditism. The WT1 IVS 9 + 5 G>A mutation was detected in one allele in the proband. The ratio of +KTS/-KTS was 0.67 in the proband's cDNA. The expression of podocyte molecules (WT1, nephrin, podocin, alpha-actinin 4 and CD2AP) were also investigated in a renal specimen of this FS patient. WT1 expression showed diffuse nuclear staining, with less obvious speckles in the patient's glomeruli than in those of controls. The distribution and intensity of podocyte molecules were altered both in normal- and abnormal-appearing glomeruli. In conclusion, the study presented a case of FS by clinical manifestation, renal pathology, karyotype analysis and genetic testing. A lower ratio of +KTS/-KTS and an abnormal distribution of WT1, as well as abnormal expressions of other podocyte molecules, were also revealed. The mechanisms of WT1 mutation causing FS still need to be investigated.

WT1 gene mutations in three girls with nephrotic syndrome

Denys-Drash syndrome and Frasier syndrome are two related conditions caused by mutations of the Wilms tumor gene, WT1. Both syndromes are characterized by male pseudohermaphrodism, a progressive glomerulopathy, and the development of genitourinary tumors. This study examines three girls with steroid-resistant nephrotic syndrome related to mutations in the WT1 gene, but with normal 46, XX karyotype and normal female phenotype. WT1 mutation analysis should be routinely done in females with steroid-resistant nephrotic syndrome.