Genetic and epigenetic alterations on the short arm of chromosome I I are involved in a majority of sporadic Wilms' tumours

Wilms' tumour is one of the most common solid tumours of childhood. I I p13 (WTI locus) and I I p15.5 (WT2 locus) are known to have genetic or epigenetic aberrations in these tumours. In Wilms' tumours, mutation of the Wilms tumour I (WTI) gene at the WTI locus has been reported, and the WT2 locus, comprising the two independent imprinted domains IGF2/H19 and KIP2/LITI, can undergo maternal deletion or alterations associated with imprinting. Although these alterations have been identified in many studies, it is still not clear how frequently combined genetic and epigenetic alterations of these loci are involved in Wilms' tumours or how these alterations occur. To answer both questions, we performed genetic and epigenetic analyses of these loci, together with an additional gene, CTNNBI, in 35 sporadic Wilms'tumours. Loss of heterozygosity of 11p15.5 and loss of imprinting of IGF2 were the most frequent genetic (29%) and epigenetic (40%) alterations in Wilms' tumours, respectively. In total, 83% of the tumours had at least one alteration at I I P15.5 and/or 11p13. One-third of the tumours had alterations at multiple loci. Our results suggest that chromosome I 1p is not only genetically but also epigenetically critical for the majority of Wilms' tumours.