Germline Wilms tumor suppressor gene (WT1) mutation leading to isolated genital malformation without Wilms tumor or nephropathy

WT1-related disorders: more than Denys-Drash syndrome

Historically, specific mutations in WT1 gene have been associated with distinct syndromes based on phenotypic characteristics, including Denys-Drash syndrome (DDS), Frasier syndrome (FS), Meacham syndrome, and WAGR syndrome. DDS is classically defined by the triad of steroid-resistant nephrotic syndrome (SRNS) onset in the first year of life, disorders of sex development (DSD), and a predisposition to Wilms tumor (WT). Currently, a paradigm shift acknowledges a diverse spectrum of presentations beyond traditional syndromic definitions. Consequently, the concept of WT1-related disorders becomes more precise. A genotype-phenotype correlation has been established, emphasizing that the location and type of WT1 mutations significantly influence the clinical presentation, the condition severity, and the chronology of patient manifestations. Individuals presenting with persistent proteinuria, with or without nephrotic syndrome, and varying degrees of kidney dysfunction accompanied by genital malformations should prompt suspicion of WT1 mutations. Recent genetic advances enable a more accurate estimation of malignancy risk in these patients, facilitating a conservative nephron-sparing surgery (NSS) approach in select cases, with a focus on preserving residual kidney function and delaying nephrectomies. Other key management strategies include kidney transplantation and addressing DSD and gonadoblastoma. In summary, recent genetic insights underscore the imperative to implement individualized, integrated, and multidisciplinary management strategies for WT1-related disorders. This approach is pivotal in optimizing patient outcomes and addressing the complexities associated with these diverse clinical manifestations.

Genotype-phenotype correlation of WT1 mutation-related nephropathy in Chinese children

Introduction

This study aimed to analyze the clinical characteristics of nephropathy associated with WT1 gene mutations in Chinese children and explore the relationship between genotype and clinical phenotype.

Methods

Cases diagnosed at the Guangzhou Women and Children's Medical Center, were combined with those retrieved from PubMed and China National Knowledge Infrastructure (CNKI) databases from January 2015 to June 2022 and integrated into a study cohort; grouped according to gene mutation sites, clinical phenotype, and renal pathological types. The clinical characteristics between groups were compared, and the relationship between genotype and age of onset, clinical phenotype, and pathological type were retrospectively analyzed.

Results

The center enrolled 15 confirmed children: seven cases of non-simple nephropathy, including Denys-Drash syndrome (DDS) and Frasier syndrome (FS); eight cases of isolated steroid-resistant nephrotic syndrome (ISRNS); and 13 cases (86.7%) that progressed to end-stage renal disease (ESRD). The initial hemoglobin and bicarbonate levels of patients with clinical non-simple nephropathy were significantly lower than those with simple nephropathy, whereas the serum creatinine levels were higher than those of patients with simple nephropathy. A total of 75 cases of nephropathy associated with WT1 mutations in the study cohort met the inclusion and exclusion criteria. The most common clinical manifestations of WT1 mutations in this cohort were DDS (29/75, 38.7%) and ISRNS (37/75, 49.3%). A renal biopsy was performed in 43 patients, and the common types of renal pathology were focal segmental glomerulosclerosis (23/43, 53.5%) and DMS (13/43, 30.2%). Within the cohort, there were 12 cases (16.0%) in the exon 8 mutation group, 32 (42.6%) in the exon 9 group, 19 (25.3%) in the intron 9 group, and 12 (16.0%) in other gene site mutation groups. Common sites of WT1 mutations in Chinese children were exons 9 and intron 9. Exon 8 mutations were uniquely correlated with the age of onset within three months [5/7; 71.4%; Adjusted standardized residual (AR) = 4.2]. The renal survival time in the exon 8 mutation group was the shortest (P = 0.003).

Discussion

The molecular and biological characteristics of WT1 mutation-related nephropathy determine the clinical type, pathological features, and renal survival time of the disease; and there was a strong correlation between the genotype and clinical phenotype.

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.

A novel WT1 gene mutation in a chinese girl with denys-drash syndrome

OBJECTIVE

Denys-Drash syndrome (DDS) is defined by the triad of Wilms tumor, nephrotic syndrome, and/or ambiguous genitalia. Genetic testing may help identify new gene mutation sites and play an important role in clinical decision-making.

METHODS

We present a patient with an XY karyotype and female appearance, nephropathy, and Wilms tumor in the right kidney. Genomic DNA was extracted from peripheral blood cells according to standard protocols. "Next-generation" sequencing (NGS) was performed to identify novel variants. The variant was analyzed with Mutation Taster, and its function was explored by a cell growth inhibition assay.

RESULTS

We found the first case of Denys-Drash syndrome with the uncommon missense mutation (c.1420C>T, p.His474 Tyr) in the WT1 gene. In silico analysis, the variant was predicted "disease-causing" by Mutation Taster. The mutated variant showed a weaker effect in inhibiting tumor cells than wild-type WT1.

CONCLUSIONS

The uncommon missense mutation (c.1420C>T, p.His474 Tyr) in the WT1 gene may be a crucial marker in DDS.

Disorders of sex development: Genetic characterization of a patient cohort

Disorders of sex development (DSDs) are congenital conditions in which the external appearance of the individual does not coincide with the chromosomal constitution or the gonadal sex. In other words, there is an ambiguous or intermediate condition between the male and female phenotypes of the anatomical sex. These atypical conditions are manifested in several ways, ranging from genital ambiguity to phenotypes that are so attenuated that they can go unnoticed or appear normal. Currently, there is a lack of understanding of the factors responsible for these outcomes; however, they are likely to be conditioned by genetic, hormonal and environmental factors during prenatal and postnatal development. The present study determined the genetic etiology of DSDs in Colombian patients by conventional cytogenetic analysis, FISH and MLPA (for SF1, DAX1, SOX9, SRY and WNT4). A cohort of 43 patients with clinical phenotypes of sex development disorder was used in the present study. Using this multistep experimental approach, a diagnostic percentage of 25.58% was obtained: 17 patients (39.53%) were classified as having gonadal development disorders, the majority of which were ovotesticular disorders with numerical and/or structural alterations of the sex chromosomes, 9 patients (20.93%) were classified as having testicular DSD with a 46,XY karyotype, and 3 patients (6.98%) as having ovarian DSD with a 46,XX karyotype. The remaining 14 patients (32.56%) were classified as 'other' since they could not be grouped into a specific class of gonadal development, corresponding to hypospadias and multiple congenital anomalies. These findings highlight the importance of histological and cytogenetic studies in a gonadal biopsy. In 11/43 cases, the multistep experimental protocol presented in the present study yielded etiological or histological findings that could be used to define the medical management of patients with DSDs. In conclusion, for the etiological diagnosis of DSDs, a broad‑spectrum approach that includes endocrinological tests, conventional karyotyping, molecular karyotyping by FISH and, molecular tests is required, in addition to gonadal tissue analyses, to identify genetic alterations.

The Wilms' tumour 1 gene as a factor in non-syndromic hypospadias: evidence and controversy

Hypospadias is one of the most frequent congenital anomalies of the male external genitalia. Its pathogenesis is due to largely unknown or poorly understood genetic factors and is further complicated by environmental-intrauterine-risk factors. One of the genes currently in focus by molecular biologists and clinicians studying syndromic forms of hypospadias is the Wilms' tumour 1 (WT1) gene. There is controversy over whether WT1 defects are also responsible for isolated hypospadias. In this review, we briefly cover the role of WT1 as a transcription factor and discuss proposed pathogenic pathways leading to hypospadias, outlining possible directions for research. We assess available evidence on the gene's mutations and polymorphisms recently suggested in the background of the disease, and examine the putative role of WT1-associated proteins. We also review relevant aspects of genome-wide association studies carried out so far, and raise some points to consider in future efforts.

Proximal Hypospadias and a Novel WT1 Variant: When Should Genetic Testing Be Considered?

We present a case of an infant with proximal hypospadias, penoscrotal transposition, and bilaterally descended testes found to have a clinically significant WT1 gene alteration on a customized disorder of sex development genetic panel in which 62 genes associated with 46, XY disorders of sex development were evaluated. This diagnosis led to early screening for and diagnosis and treatment of Wilms tumor. Patients with proximal hypospadias are not routinely evaluated by genetic testing, and when initial hormonal analyses are within normal ranges for a typical male patient, the genital atypia is usually attributed to an isolated anatomic abnormality. There is no consensus among urologists, endocrinologists, or geneticists regarding when genetic testing is warranted in these patients or the extent of genetic testing that should be pursued. However, given advances in genetic testing and the discovery of more genetic variants, the genetic evaluation of infants with proximal hypospadias should be considered on an individual patient basis. Only with continued evaluation and the identification of further genetic variants can we establish future parameters for genetic evaluation in patients with proximal hypospadias and more appropriately counsel patients and their families regarding the implications of these variants.

Genetic and environmental factors in the aetiology of hypospadias

This article reviews the current evidence and knowledge of the aetiology of hypospadias. Hypospadias remains a fascinating anomaly of the male phallus. It may be an isolated occurrence or part of a syndrome or field defect. The increasing use of assisted reproductive techniques and hormonal manipulation during pregnancy may have been associated with an apparent rise in the incidence of hypospadias. Genetic studies and gene analysis have suggested some defects that could result in hypospadias. New light has also been thrown on environmental factors that could modulate candidate genes, causing altered development of the male external genitalia.

Extensive clinical, hormonal and genetic screening in a large consecutive series of 46,XY neonates and infants with atypical sexual development

Background

One in 4500 children is born with ambiguous genitalia, milder phenotypes occur in one in 300 newborns. Conventional time-consuming hormonal and genetic work-up provides a genetic diagnosis in around 20-40% of 46,XY cases with ambiguous genitalia. All others remain without a definitive diagnosis. The investigation of milder cases, as suggested by recent reports remains controversial.

Methods

Integrated clinical, hormonal and genetic screening was performed in a sequential series of 46, XY children, sex-assigned male, who were referred to our pediatric endocrine service for atypical genitalia (2007–2013).

Results

A consecutive cohort of undervirilized 46,XY children with external masculinization score (EMS) 2–12, was extensively investigated. In four patients, a clinical diagnosis of Kallmann syndrome or Mowat-Wilson syndrome was made and genetically supported in 2/3 and 1/1 cases respectively. Hormonal data were suggestive of a (dihydro)testosterone biosynthesis disorder in four cases, however no HSD17B3 or SRD5A2 mutations were found. Array-CGH revealed a causal structural variation in 2/6 syndromic patients. In addition, three novel NR5A1 mutations were found in non-syndromic patients. Interestingly, one mutation was present in a fertile male, underlining the inter- and intrafamilial phenotypic variability of NR5A1-associated phenotypes. No AR, SRY or WT1 mutations were identified.

Conclusion

Overall, a genetic diagnosis could be established in 19% of non-syndromic and 33% of syndromic cases. There is no difference in diagnostic yield between patients with more or less pronounced phenotypes, as expressed by the external masculinisation score (EMS). The clinical utility of array-CGH is high in syndromic cases. Finally, a sequential gene-by-gene approach is time-consuming, expensive and inefficient. Given the low yield and high expense of Sanger sequencing, we anticipate that massively parallel sequencing of gene panels and whole exome sequencing hold promise for genetic diagnosis of 46,XY DSD boys with an undervirilized phenotype.

Electronic supplementary material

The online version of this article (doi:10.1186/s13023-014-0209-2) contains supplementary material, which is available to authorized users.

The mutational spectrum of WT1 in male infertility

PURPOSE

We evaluated the impact of WT1 mutations in isolated severe spermatogenic impairment in a population of European ancestry. WT1 was first identified as the gene responsible for Wilms tumor. It was later associated with a plethora of clinical phenotypes often accompanied by urogenital defects and male infertility. The recent finding of WT1 missense mutations in Chinese azoospermic males without major gonadal malformations broadened the phenotypic spectrum of WT1 defects and motivated this study.

MATERIALS AND METHODS

We analyzed the WT1 coding region in a cohort of 194 Portuguese patients with nonobstructive azoospermia and in 188 with severe oligozoospermia with increased depth for the exons encoding the regulatory region of the protein. We also analyzed a group of 31 infertile males with a clinical history of unilateral or bilateral cryptorchidism and 1 patient with anorchia.

RESULTS

We found 2 WT1 missense substitutions at higher frequency in patients than in controls. 1) A novel variant in exon 1 (p.Pro130Leu) that disrupted a mammalian specific polyproline stretch in the self-association domain was more frequent in azoospermia cases (0.27% vs 0.13%, p = 0.549). 2) A rare variant in a conserved residue in close proximity to the first zinc finger (pCys350Arg) was more frequent in severe oligozoospermia cases (0.80% vs 0.13%, p = 0.113).

CONCLUSIONS

Results suggest a role for rare WT1 damaging variants in severe spermatogenic failure in populations of European ancestry. Large multicenter studies are needed to fully assess the contribution of WT1 genetic alterations to male infertility in the absence of other disease phenotypes.

A novel WT1 gene mutation in a patient with Wilms' tumor and 46, XY gonadal dysgenesis

Denys-Drash syndrome (DDS) is a rare genetic disorder featuring the triad of Wilms' tumor, early-onset renal failure, and 46, XY disorder of sex development. DDS is usually caused by heterozygous missense mutations in the zinc-finger region of the WT1 gene. The most frequent constitutional WT1 mutations in DDS patients are missense mutations in exons 8 and 9. We present a new case of variable DDS in a child who was found to have a novel heterozygous missense mutation in exon 7 (c.905G>T) and a splicing mutation in exon 6 (IVS6-1G>T).

Analysis of the Wilms' tumor suppressor gene (WT1) in patients 46,XY disorders of sex development

CONTEXT

The Wilms' tumor suppressor gene (WT1) is one of the major regulators of early gonadal and kidney development. WT1 mutations have been identified in 46,XY disorders of sex development (DSD) with associated kidney disease and in few isolated forms of 46,XY DSD.

OBJECTIVE

The objective of the study was the evaluation of WT1 mutations in different phenotypes of isolated 46,XY DSD and clinical consequences.

DESIGN

The design of the study was: 1) sequencing of the WT1 gene in 210 patients with 46,XY DSD from the German DSD network, consisting of 150 males with severe hypospadias (70 without cryptorchidism, 80 with at least one cryptorchid testis), 10 males with vanishing testes syndrome, and 50 raised females with partial to complete 46,XY gonadal dysgenesis; and 2) genotype-phenotype correlation of our and all published patients with 46,XY DSD and WT1 mutations.

RESULTS

We have detected WT1 mutations in six of 80 patients with severe hypospadias (7.5%) and at least one cryptorchid testis and in one of 10 patients with vanishing testes syndrome (10%). All patients except one developed Wilms' tumor and/or nephropathy in childhood or adolescence.

CONCLUSION

WT1 analysis should be performed in newborns with complex hypospadias with at least one cryptorchid testis and in isolated 46,XY partial to complete gonadal dysgenesis. Kidney disease might not develop until later life in these cases. WT1 analysis is mandatory in all 46,XY DSD with associated kidney disease. WT1 analysis is not indicated in newborns with isolated hypospadias without cryptorchidism. Patients with WT1 mutations should be followed up closely because the risk of developing a Wilms' tumor, nephropathy, and/or gonadal tumor is very high.

Case report: WT1 exon 6 truncation mutation and ambiguous genitalia in a patient with Denys-Drash syndrome

Denys-Drash syndrome is a rare genetic disorder featuring the triad of congenital nephropathy, Wilms tumor, and intersex disorders (XY under-virilization or XY female). Denys-Drash syndrome is associated with constitutional mutations in the Wilms tumor suppressor gene WT1. Unlike WAGR (Wilms tumor, aniridia, genitourinary anomalies, and mental retardation) syndrome, with its complete deletion of one copy of WT1, Denys-Drash syndrome is generally caused by a dominant-negative mutation. We present a new case of Denys-Drash syndrome in a patient initially diagnosed with XY ambiguous genitalia/partial androgen insensitivity syndrome, who was found to have a novel nonsense mutation in exon 6 leading to a stop codon and hence a truncated protein. Based on lessons learned from this patient, the diagnosis of Denys-Drash syndrome should be considered in the presence of ambiguous genitalia and partial androgen insensitivity.

Frequency and heritability of WT1 mutations in nonsyndromic Wilms' tumor patients: a UK Children's Cancer Study Group Study

PURPOSE

Constitutional WT1 mutations in patients with Wilms' tumor (WT) have specifically been associated with genitourinary abnormalities, such as cryptorchidism and hypospadias. We sought to ascertain the frequency and heritability of constitutional WT1 mutations in nonsyndromic WT patients.

PATIENTS AND METHODS

Constitutional DNA from 282 patients treated at seven United Kingdom Children's Cancer Study Group centers was screened for WT1 mutations using heteroduplex analysis. Bidirectional sequencing was used to confirm the mutation and to analyze the corresponding parental DNA samples.

RESULTS

Five different constitutional WT1 mutations were identified in six children. Mutations in four patients were confirmed to be de novo, and all five mutations are predicted to produce truncated protein. The WT1 mutation group had a young median age at diagnosis of 13.8 months, compared with 34.9 months in the group in whom no WT1 mutations were found; four were female and two were male; and all tumors were of favorable histology. The three tumors with known histologic subtype were stromal-predominant. Contrary to expectation, four of six mutations occurred in children with unilateral tumors without any associated genitourinary abnormality.

CONCLUSION

Constitutional WT1 mutations occur with a low frequency (2.1%; 95% CI, 0.8% to 4.6%) in nonsyndromic WT patients. Most mutations occurred in children with unilateral WT without associated genitourinary abnormalities, creating difficulties in identifying individuals with germline mutations on phenotype alone. Two factors that may indicate that an individual is carrying a germline WT1 mutation are an early age of onset and stromal-predominant histology of the WT.

Absence of Y chromosome microdeletions in patients with cryptorchidism and hypospadias

Microdeletions of the Y chromosome have been observed in some patients with cryptorchidism and severe defects of spermatogenesis. We investigated whether microdeletions of the Y chromosome may be present in patients with cryptorchidism and hypospadias. Peripheral blood was obtained from 20 male patients 5.8 +/- 4.1 years (range: 0.4-14 years) with cryptorchidism and hypospadias for somatic DNA analysis of Y chromosome using multiplex polymerase chain reaction. These patients had no identifiable genetic syndrome, other genitourinary malformations or an abnormal karyotype. We evaluated the presence or absence of amplification using a set of 34 different sequence-tagged sites (STS) in each patient. All patients showed normal length amplifications for each of the regions evaluated, suggesting that microdeletions of the Y chromosome are not a frequent cause of hypospadias associated with cryptorchidism.

Responsiveness of chemotherapy based on the histological type and Wilms' tumor suppressor gene mutation in bilateral Wilms' tumor

To clarify a characteristic of bilateral Wilms' tumor (WT), we examined the clinical and histological features, chemotherapy response and mutations in Wilms' tumor suppressor gene (WT1) in five patients. Deoxyribonucleic acid was extracted from peripheral lymphocytes and tumor samples, and direct DNA sequencing was performed to detect WT1 mutations. Paraffin sections were stained with H&E for histological review and immunostained with anti-WT1, anti-Ki-67, anti-S-100 protein and antimyogenin antibodies. In contrast to the single case of epithelial-type WT, the other four cases were fetal rhabdomyomatous nephroblastoma (FRN) or contained a premature skeletal muscle component and appeared to be resistant to chemotherapy because there was no reduction in tumor volume. However, after chemotherapy, most of the tumor components changed into mature striated muscle cells, most of which immunostained almost completely negative for Ki-67. All four cases had the same point mutation of WT1. From our results, the histological findings correlated with WT1 mutations in bilateral WT. The tumor volume of FRN did not decrease in response to chemotherapy. It is possible to predict the chemotherapy response by examining bilateral WT for WT1 mutations and the histological characteristics of tumors.

Recent advances in Wilms tumor genetics

The past decade has witnessed substantial growth in our knowledge of the genes and loci that are altered in Wilms tumor. Although Wilms tumor was one of the original paradigms of Knudson's two-hit model of cancer formation, it has become apparent that several genetic events contribute to Wilms tumorigenesis. Recent research has identified targets and regulators of the first Wilms tumor gene, WT1, has uncovered several candidate genes at the second Wilms tumor locus, WT2, and has identified two familial Wilms tumor loci, FWT1 and FWT2. The recent discovery of activating beta-catenin mutations in some Wilms tumors has also implicated the Wnt signaling pathway in this neoplasm. Recurrent abnormalities of other loci, including 16q, 1p, and 7p, have indicated that these sites may harbor Wilms tumor genes. An enhanced understanding of these and other genetic lesions will provide the foundation for novel targeted Wilms tumor therapies.

The genetics of male undermasculinization

A review of the genetics of male undermasculinization must encompass a description of the embryology of the genital system. The dimorphism of sex development consequent upon the formation of a testis and the subsequent secretion of hormones to impose a male phenotype is highlighted. Thus, an understanding of the causes of male undermasculinization (manifest as XY sex reversal, complete and partial) includes reviewing the genetic factors which control testis determination and the production and action of testicular hormones. The study of disorders of male sex development has contributed substantially to knowledge of normal male development before birth. This knowledge has been complimented in recent years by the use of targeted murine gene disruption experiments to study the sex phenotype, although murine and human phenotypes are not always concordant. The investigation of disorders associated with male undermasculinization of prenatal onset is described briefly to complete the review.