A very small percentage - one to two percent -- of children with Wilms' tumor have a family member or relative who also had Wilms' tumor. These children have a higher risk of developing bilateral tumors (tumors found in both kidneys) than those children with nonfamilial (also called sporadic) cases of Wilms' tumor.
In approximately 15 percent of those diagnosed with Wilms' tumor, other congenital abnormalities also appear. Certain types of birth defects, such as genitourinary abnormalities, hemihypertrophy, microcephaly, and some syndromes -- Beckwith-Wiedemann Syndrome, Denis-Drash Syndrome, and WAGR (Wilms' tumor, Aniridia, Genitourinary abnormalities, mental Retardation) -- are associated with Wilms' tumor as well.
To date, there appears to be no proven connection between environmental factors and Wilms' tumor.
