Three loci have been implicated in familial Wilms tumour: WT1 located on chromosome 11p13, FWT1 on 17q12-q21, and FWT2 on 19q13. Two out of 19 Wilms tumour families evaluated showed strong evidence against linkage at all three loci. Both of these families contained at least three cases of Wilms tumour indicating that they were highly likely to be due to genetic susceptibility and therefore that one or more additional familial Wilms tumour susceptibility genes remain to be found.