From NCBI curation
PAX6-related aniridia occurs either as an isolated ocular abnormality or as part of the Wilms tumor-aniridia-genital anomalies-retardation (WAGR) syndrome. Aniridia is a pan ocular disorder affecting the cornea, iris, intraocular pressure (resulting in glaucoma), lens (cataract and lens subluxation), fovea (foveal hypoplasia), and optic nerve (optic nerve coloboma and hypoplasia). Individuals with aniridia characteristically show nystagmus and impaired visual acuity (usually 20/100 - 20/200); however, milder forms of aniridia with subtle iris architecture changes, good vision, and normal foveal structure do occur. Other ocular involvement may include strabismus and occasionally microphthalmia. Although the severity of aniridia can vary between and within families, little variability is usually observed in the two eyes of an affected individual. WAGR syndrome. The risk for Wilms tumor is 42.5%-77%; of those who develop Wilms tumor, 90% do so by age four years and 98% by age seven years. Genital anomalies in males can include cryptorchidism and hypospadias (sometimes resulting in ambiguous genitalia), urethral strictures, ureteric abnormalities, and gonadoblastoma. While females typically have normal external genitalia, they may have uterine abnormalities and streak ovaries. Intellectual disability (defined as IQ <74) is observed in 70%; behavioral abnormalities include attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder, anxiety, depression, and obsessive-compulsive disorder. Other individuals with WAGR syndrome can have normal intellect without behavioral issues.

From OMIM
Wilms tumor is the most common renal tumor of childhood, occurring with an incidence of 1 in 10,000 and with a median age of diagnosis between 3 and 4 years of age. Wilms tumors are thought to develop from abnormally persistent embryonal cells within nephrogenic rests. Histologically, Wilms tumor mirrors the development of the normal kidney and classically consists of 3 cell types: blastema, epithelia, and stroma (summary by Slade et al., 2010). Genetic Heterogeneity of Wilms Tumor Susceptibility to Wilms tumor is genetically heterogeneous. WT2 (194071) is caused by mutation in the H19/IGF2-imprinting control region (ICR1; 616186) on chromosome 11p15. WT3 (194090) represents a locus mapped to chromosome 16q. WT4 (601363) represents a locus mapped to chromosome 17q12-q21. WT5 (601583) is caused by mutation in the POU6F2 gene (609062) on chromosome 7p14. WT6 (616806) is caused by mutation in the REST gene (600571) on chromosome 4q12. WT7 (621332) is caused by mutation in the TRIM28 gene (601742) on chromosome 19q13. Mutations in the BRCA2 gene (600185) have also been reported in Wilms tumor. Rare somatic and constitutional disruption of the HACE1 gene (610876) has also been reported in Wilms tumor. Somatic mutations in the glypican-3 gene (GPC3; 300037) have been described in Wilms tumor. Somatic mutations in the WTX gene (300647) on the single X allele in tumors from males and on the active X allele in tumors from females have also been described.  http://www.omim.org/entry/194070

From MedlinePlus Genetics
Wilms tumor is a form of kidney cancer that primarily develops in children. Nearly all cases of Wilms tumor are diagnosed before the age of 10, with two-thirds being found before age 5.

Wilms tumor is often first noticed because of abdominal swelling or a mass in the kidney that can be felt upon physical examination. Some affected children have abdominal pain, fever, a low number of red blood cells (anemia), blood in the urine (hematuria), or high blood pressure (hypertension). Additional signs of Wilms tumor can include loss of appetite, weight loss, nausea, vomiting, and tiredness (lethargy).

Wilms tumor can develop in one or both kidneys. About 5 to 10 percent of affected individuals develop multiple tumors in one or both kidneys. Wilms tumor may spread from the kidneys to other parts of the body (metastasize). In rare cases, Wilms tumor does not involve the kidneys and occurs instead in the genital tract, bladder, abdomen, chest, or lower back. It is unclear how Wilms tumor develops in these tissues.

With proper treatment, children with Wilms tumor have a 90 percent survival rate. However, the risk that the cancer will come back (recur) is between 15 and 50 percent, depending on traits of the original tumor. Tumors usually recur in the first 2 years following treatment and develop in the kidneys or other tissues, such as the lungs. Individuals who have had Wilms tumor may experience related health problems or late effects of their treatment in adulthood, such as decreased kidney function, heart disease, and development of additional cancers.  https://medlineplus.gov/genetics/condition/wilms-tumor