Prophylactic bilateral salpingo-oopherectomy in a 17-year-old with Frasier syndrome reveals gonadoblastoma and seminoma: a case report

Spectrum of Clinical Manifestations in Children With WT1 Mutation: Case Series and Literature Review

BACKGROUND

Mutations of the Wilms tumor suppressor-1 gene (WT1) are associated with life-threatening glomerulopathy, disorders of sexual development, Wilm's tumor, and gonadal malignancies. Our objectives were to describe the clinical presentations, age of progression, and onset of complications of WT1 mutation through a case series and literature review.

METHODS

A retrospective study included all patients followed at the University of Miami/Holtz Children's Hospital from January 2000 to December 2020 with a diagnosis of WT1 mutation. A literature review of WT1 mutation cases was analyzed for clinical manifestations, karyotype, and long-term outcomes.

RESULTS

The WT1 mutation was identified in 9 children, median age at presentation of 0.9 years (range 1 week to 7 years). A total of four had female phenotypes, and 5 had abnormalities of male external genitalia, while all had XY karyotypes. All progressed to end-stage kidney disease (ESKD) and received a kidney transplant at a median age of 5 years (1.5-15 years). During a median time of follow-up of 9 years (range 2-28 years), there were 2 allograft losses after 7 and 10 years and no evidence of post-transplant malignancy. From 333 cases identified from the literature review, the majority had female phenotype 66% (219/333), but the predominant karyotype was XY (55%, 183/333). Of the female phenotypes, 32% (69/219) had XY sex reversal. Wilm's tumor occurred in 24%, predominantly in males with gonadal anomalies.

CONCLUSIONS

Early recognition of WT1 mutation is essential for comprehensive surveillance of potential malignancy, avoidance of immunosuppressants for glomerulopathy, and establishing long-term multidisciplinary management.

Novel Function of a Transcription Factor WT1 in Regulating Decidualization in Human Endometrial Stromal Cells and Its Molecular Mechanism

The Wilms tumor suppressor gene (WT1) encodes an essential transcription factor regulating mammalian urogenital development. However, the function of WT1 in human endometrium is still unclear. The current study examined the involvement of WT1 in the regulation of IGF-binding protein-1 (IGFBP-1) and prolactin (PRL), which are specific markers of decidualization, in human endometrial stromal cells (ESCs) undergoing decidualization. ESCs isolated from proliferative-phase endometrium were incubated with cyclic adenosine monophosphate (cAMP) to induce decidualization. cAMP increased WT1 expression with the induction of IGFBP-1 and PRL. Knockdown of WT1 by small interfering RNA inhibited cAMP-induced expression of IGFBP-1 and PRL. cAMP also induced the recruitment of WT1 to the IGFBP-1 and PRL promoters. To investigate the mechanism by which WT1 is upregulated by cAMP, we focused on C/EBPβ, a gene that regulates the expression of many genes during decidualization. Knockdown of C/EBPβ decreased cAMP-increased WT1 expression. cAMP increased the recruitment of C/EBPβ to the WT1 enhancer that is located approximately 14,000 bp downstream from the transcription start site. To test the endogenous function of the WT1 enhancer region on WT1 expression, the endogenous WT1 enhancer region was deleted by CRISPR/Cas9 system in HEK293 cells. The increase of WT1 expression by cAMP was not observed in the enhancer-deleted clones. Chromatin immunoprecipitation assay revealed that this enhancer region has high levels of H3K27ac and H3K4me1, which are active enhancer marks. These results show the role of WT1 in regulating decidualization in human ESCs. C/EBPβ is an upstream gene that regulates WT1 expression by binding to the novel enhancer region.

Gonadal tumor in Frasier syndrome: a review and classification

Frasier syndrome is a rare inherited disease characterized by steroid-resistant nephrotic syndrome, gonadal tumor, and male pseudohermaphroditism (female external genitalia with sex chromosomes XY), which is based on a splice site mutation of Wilms tumor-suppressor gene 1 (WT1). Several unusual Frasier syndrome cases have been reported in which male pseudohermaphroditism was absent. We reviewed 88 Frasier syndrome cases in the literature and classified them into three types (type 1-3) according to external genitalia and sex chromosomes, and described their clinical phenotypes. Type 1 Frasier syndrome is characterized by female external genitalia with 46,XY (n = 72); type 2 by male external genitalia with 46,XY (n = 8); and type 3 by female external genitalia with 46,XX (n = 8). Clinical course differs markedly among the types. Although type 1 is noticed at the mean age of 16 due to mainly primary amenorrhea, type 2 and 3 do not present delayed secondary sex characteristics, making diagnosis difficult. The prevalence of gonadal tumor is high in type 1 (67%) and also found in 3 of the 8 type 2 cases, but not in any type 3 cases, which emphasize that preventive gonadectomy is unnecessary in type 3. On the basis of our findings, we propose a new diagnostic algorithm for Frasier syndrome.

Frasier syndrome: four new cases with unusual presentations

Frasier syndrome (FS) is characterized by gonadal dysgenesis and nephropathy. It is caused by specific mutations in the Wilms' tumor suppressor gene (WT1) located in 11p23. Patients with the 46,XY karyotype present normal female genitalia with streak gonads, and have higher risk of gonadal tumor, mainly, gonadoblastoma. Therefore, elective bilateral gonadectomy is indicated. Nephropathy in FS consists in nephrotic syndrome (NS) with proteinuria that begins early in childhood and progressively increases with age, mainly due to nonspecific focal and segmental glomerular sclerosis (FSGS). Patients are generally unresponsive to steroid and immunosuppressive therapies, and will develop end-stage renal failure (ESRF) during the second or third decade of life. We report here four cases of FS diagnosis after identification of WT1 mutations. Case 1 was part of a large cohort of patients diagnosed with steroid-resistant nephrotic syndrome, in whom the screening for mutations within WT1 8-9 hotspot fragment identified the IVS9+5G>A mutation. Beside FS, this patient showed unusual characteristics, such as urinary malformation (horseshoe kidney), and bilateral dysgerminoma. Cases 2 and 3, also bearing the IVS9+5G>A mutation, and case 4, with IVS9+1G>A mutation, were studied due to FSGS and/or delayed puberty; additionally, patients 2 and 4 developed bilateral gonadal tumors. Since the great majority of FS patients have normal female external genitalia, sex reversal is not suspected before they present delayed puberty and/or primary amenorrhea. Therefore, molecular screening of WT1 gene is very important to confirm the FS diagnosis.

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.

Genotype/phenotype correlation in nephrotic syndrome caused by WT1 mutations

BACKGROUND AND OBJECTIVES

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.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

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.

RESULTS

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).

CONCLUSIONS

(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.

New insights into type II germ cell tumor pathogenesis based on studies of patients with various forms of disorders of sex development (DSD)

Disorders of sex development (DSD), previously known as intersex, refer to congenital conditions in which development of chromosomal, gonadal, or anatomical sex is atypical. Patients with specific variants of this disorder have an elevated risk for the development of so-called type II germ cell cancers, i.e., the seminomatous and nonseminatous tumors, referred to as germ cell tumors (GCTs). Specifically DSD patients with gonadal dysgenesis or hypovirilization are at risk. A prerequisite for type II GCT formation is the presence of a specific part of the Y chromosome (referred to as the GBY region), with the TSPY gene being the most likely candidate. Also the octamer binding transcription factor OCT3/4 is consistently expressed in all type II GCTs with pluripotent potential, as well as in the precursor lesions carcinoma in situ (CIS) in case of a testis and gonadoblastoma (GB) in the DSD gonad. The actual risk for malignant transformation in individual DSD patients is hard to predict, because of confusing terminology referring to the different forms of DSD, and unclear criteria for identification of the presence of malignant germ cells, especially in young patients. This is specifically due to the phenomenon of delay of germ cell maturation, which might result in over diagnosis. This review will give novel insight into the pathogenesis of the type II GCTs through the study of patients with various forms of DSD for which the underlying molecular defect is known. To allow optimal understanding of the pathogenesis of this type of cancers, first normal gonadal development, especially regarding the germ cell lineage, will be discussed, after which type II GCTs will be introduced. Subsequently, the relationship between type II GCTs and DSD will be described, resulting in a number of new insights into the development of the precursor lesions of these tumors.