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PURPOSE OF REVIEW: To review the 2009/2010 literature on pediatric genitourinarytumors and highlight the most significant publications. RECENT FINDINGS: New techniques such as gene expression profiling, PET, nephron-sparing surgery, and stem cell transplantation are being incorporated into contemporary treatments for pediatric patients with genitourinary tumors. Biologic markers are increasingly being used to help with risk stratification of patients. WT1 mutation and 11p15 loss of heterozygosity have been associated with relapse in very low-risk Wilms tumors treated with surgery alone and may help reduce the use of chemotherapy insome children. Discussion continues on the use of fusion gene status to risk stratify alveolar rhabdomyosarcoma. Meta-analysis of the use of high-dose chemotherapy with autologous hematopoetic stem cell rescue in patients with relapsed Wilms tumor and rhabdomyosarcoma suggests that some patients may benefit more from conventional salvage chemotherapy. New agents are needed for patients with high-risk and relapsed disease to improve outcomes. SUMMARY: In general, the prognosis for patients with pediatric genitourinary tumors is favorable. The elucidation of the molecular abnormalities in these tumors is determining risk stratification, treatment strategies, and candidates for new drug development.

The Wilms tumor 1 (WT1) gene is currently in focus by pediatric nephrologists asits mutations are associated with nephrotic syndrome, especially as part of complex clinical entities like Denys-Drash or Frasier syndrome. Renal failure may also develop in young WAGR patients, whose condition is attributed to a deletionat chromosomal region 11p13. However, only limited data exist on WT1 microdeletions. A 30-year-old male patient, with a history of genital malformations, a Wilms tumor manifested during the treatment of acute lymphoid leukemia (ALL) at the age of 4, and a cerebellar angioblastoma, was referred with proteinuria and a reduced glomerular filtration rate (GFR). Kidney biopsy revealed FSGS. Although ALL WT1 exons were amplified with polymerase chain reaction (PCR) and sequenced, none of them showed a mutation. However, an formalin-fixed, paraffin- embedded (FFPE) tissue sample of the patient's childhood Wilms tumor showed WT1- positivity restricted to the renal tumor cells, so the WT1 gene was investigated further. Using quantitative reverse transcription PCR (qRT-PCR), the gene was found to be present in only one copy in the patient's genomic DNA sample, while both copies were detected in both parents. In the patient's sister, the proximal region of WT1 was shown to have an extra copy. Evidence suggests that a heterozygous microdeletion of the gene WT1 is responsible for the patient's disease. It seems reasonable to assume a possible abnormality affecting meiotic crossing over at the WT1 locus in one of the parents.