Congenital Anomalies of the Kidneys and Urinary Tract (CAKUT)

Ectopic kidney (called "pelvic kidney" when the kidney does not migrate above the pelvic rim) occurs in about 1/1000 to 1/5000 patients. It consists of a kidney which does not migrate and ascend normally during development. The abnormally located kidney usually has somewhat diminished function when carefully measured. There is a 20% reported incidence of vesicoureteral reflux, but most cases of VUR are mild and self-resolve. Complications are rare, but can include urinary tract infection, ureteral obstruction, kidney stones, or incontinence from ectopic ureter. The contralateral kidney is usually normal, but other congenital abnormalities of the kidneys and urinary tract are sometimes observed, including renal dysplasia, cryptorchidism, and hypospadias. In the absence of other anomalies, the prognosis for a patient with an ectopic kidney is excellent.

WAGR syndrome is a genetic condition which almost always has aniridia. It is also associated with an increased risk for Wilms tumor.

• Per GeneReviews, the "risk for children with a molecularly confirmed heterozygous contiguous-gene deletion of PAX6 and WT1 at chromosome 11p13 is between 42.5% and 77% [Fischbach et al 2005, Clericuzio et al 2011]. Of those who develop Wilms tumor, 90% do so by age four years and 98% by age seven years. Compared to children with isolated Wilms tumor, children with WAGR syndrome are more likely to develop bilateral tumors and to have an earlier age of diagnosis and more favorable tumor histology with a better prognosis [Halim et al 2012]."

• Children with WAGR syndrome can also have renal function abnormalities and proteinuria. They can have genitourinary abnormalities (ambiguous genitalia, urethral strictures, ureteral abnormalities, gonadoblastoma, cryptorchidism (most common feature, seen in 60%), and hypospadias). Females may have uterine abnormalities including bicornuate uterus and streak ovaries; their external genitalia are usually normal [Fischbach et al 2005].

WAGR syndrome is characterized by WT, aniridia, genitourinary abnormalities and intellectual disability. A significant risk of nephropathy also exists. This constellation of features is due to contiguous gene deletions in chromosome 11p13 including WT1, PAX6, and other genes... The median age of WT diagnosis is around 1 year of age in WT1-affected individuals, about 2 to 3 years earlier than the age of WT diagnosis in children without a germline mutation. There have been reports of children with WT1 mutations developing WT up to 8 years of age. The risk of WT in WAGR is approximately 50% (Kalish et al, Surveillance Recommendations for Children with Overgrowth Syndromes and Predisposition to Wilms Tumor and Hepatoblastoma, CCR Pediatric Oncology Series, 2017). Guidelines for Wilms tumor surveillance in this population recommend renal ultrasound every 3 months until 7 years of age.