Cytogenetic And Molecular Features Of Wilms Tumor

Recessive cancer genes (suppressor genes) play an important role in the pathogenesis of Wilms' tumor. With the use of cytogenetic techniques and molecular analysis for restriction length polymorphism, homozygosity or hemizygosity for a small deletion on chromosome 11 (11p13) has been detected in the tumor cells of Wilms' tumor. This Wilms' tumor 1 (WT1) gene encodes a transcription factor that is important in normal kidney and gonadal development. Germ line mutations within the WT1 gene have been identified in WAGR and DDS and some bilateral Wilms' tumors. Specific mutations of WT1 have been found in only 10% or less of sporadic Wilms' tumors.

A second Wilms' tumor locus (WT2) maps to chromosome 11p15.5, based on tumor-specific loss of heterozygosity. The Beckwith-Wiedemann syndrome also maps to this location. The copy of 11p15 that is lost is derived from the mother, suggesting that the 11p15 locus is subject to genomic imprinting. Twenty percent of Wilms' tumor syndromes have allelic loss of the long arm of chromosome 16. It is felt that there are other yet unidentified loci where mutation may predispose to Wilms' tumor formation.

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