Two familial WT genes have been localized, FWT1 at 17q12-q21 and FWT2 at 19q13.4; lack of linkage in some WT families to either of these loci implies the existence of at least one additional familial WT gene.
The results confirm the role of FWT1 in susceptibility to WT, provide strong evidence for genetic heterogeneity in familial WT and suggest there are phenotypic differences between familial WT due to FWT1, familial WT due to other genes and non-familial WT.