WT1 Pathogenic Variants are Associated with a Broad Spectrum of Differences in Sex Development Phenotypes and Heterogeneous Progression of Renal Disease

Wilms’ tumor suppressor gene 1 (<i>WT1</i>) plays an essential role in urogenital and kidney development. Heterozygous germline pathogenic allelic variants of <i>WT1</i> have been classically associated with Denys–Drash syndrome (DDS) and Frasier syndrome (FS). Usually, exonic pathogenic missense variants in the zinc finger region are the cause of DDS, whereas pathogenic variants affecting the canonic donor lysine-threonine-serine splice site in intron 9 cause FS. Phenotypic overlap between <i>WT1</i> disorders has been frequently observed. New <i>WT1</i> variant-associated phenotypes, such as 46,XX testicular/ovarian-testicular disorders of sex development (DSD) and primary ovarian insufficiency, have been reported. In this report, we describe the phenotypes and genotypes of 7 Brazilian patients with pathogenic <i>WT1</i> variants. The molecular study involved Sanger sequencing and massively parallel targeted sequencing using a DSD-associated gene panel. Six patients (5 with a 46,XY karyotype and 1 with a 46,XX karyotype) were initially evaluated for atypical genitalia, and a 46,XY patient with normal female genitalia sought medical attention for primary amenorrhea. Germ cell tumors were identified in 2 patients, both with variants affecting alternative splicing of <i>WT1</i> between exons 9 and 10. Two pathogenic missense <i>WT1</i> variants were identified in two 46,XY individuals with Wilms’ tumors; both patients were &#x3c;1 year of age at the time of diagnosis. A novel <i>WT1</i> variant<i>,</i> c.1453_1456 (p.Arg485Glyfs*14), was identified in a 46,XX patient with testicular DSD. Nephrotic proteinuria was diagnosed in all patients, including 3 who underwent renal transplantation after progressing to end-stage kidney disease. The expanding phenotypic spectrum associated with <i>WT1</i> variants in XY and XX individuals confirms their pivotal role in gonadal and renal development as well as in tumorigenesis, emphasizing the clinical implications of these variants in genetic diagnosis.