Analysis of exons 2-10 of the WT1 gene in constitutional DNA from five patients with DDS was carried out using the polymerase chain reaction (PCR) and direct DNA sequencing.
The WT1 gene is normally expressed during gonadal development and specific mutations in heterozygous form cause Drash syndrome, characterized by male pseudohermaphroditism and gonadal dysgenesis, renal failure and a predisposition for Wilms' tumour.
Mutations in the donor splice site in intron 9 of the Wilms' tumor (WT1) gene have been shown to cause Frasier syndrome and are distinct from WT1 exon mutations associated with Denys-Drash syndrome.
The decision to do prophylactic nephrectomies was based on the genetic identification of WT1 mutations supporting a diagnosis of incomplete DDS, with the potential for increased risk of malignancy with the development of Wilms' tumour.
The mutations found in our cases occurred in the same exon of the WT1 gene as detected in Denys-Drash syndrome (DDS) and could not be explained by the previously proposed mechanism.
In this report, we describe a family with the well-known missense mutation in exon 9 of the WT1 gene, 1180C>T (R394W), causing incomplete DDS and no symptoms in their father.
Mutations in the WT1 gene causing Wilms tumors were first reported in WAGR syndrome (Wilms tumor, Aniridia, Genitourinary malformation, mental Retardation) and Denys Drash syndrome (pseudohermaphroditism, Wilms tumor, nephropathy), but only in a few patients with hypospadias and cryptorchidism without other signs of Denys Drash (DDS) or WAGR syndrome WT1 mutations were identified.
Deletions of the WT1 gene or point mutations which destroy the DNA binding activity of the protein are associated with the development of the pediatric nephroblastoma Wilms tumor and Denys-Drash syndrome.
A point mutation found in the WT1 gene in a sporadic Wilms' tumor without genitourinary abnormalities is identical with the most frequent point mutation in Denys-Drash syndrome.
All described patients presented with similar neuroimaging features including thin corpus callosum, mild to moderate cerebellar atrophy and diffuse periventricular and profound hypomyelinating leukodystrophy involving supratentorial white matter with classical compromise linked to inherited non-somatic WT1 gene mutations in a similar pattern to Denys-Drash syndrome, including nephrotic syndrome with different glomerular disease, chronic renal failure, intersex disorder with ambiguous genitalia, and early occurrence of specific tumors, such as Wilms' tumor and gonadoblastoma.
Constitutional missense mutations in the WT1 gene are usually associated with the Denys-Drash syndrome, characterized by a rapid progressive nephropathy, male pseudohermaphroditism, and an increased risk for Wilms tumor.
We encountered a patient with Denys-Drash syndrome associated with WT whose WT1 gene had a homozygous point mutation not only in WT but also in renal tissue adjacent to the WT and in the germline.