CONSTITUTIONAL RELAXATION OF INSULIN-LIKE GROWTH-FACTOR-II GENE IMPRINTING ASSOCIATED WITH WILMS-TUMOR AND GIGANTISM

We have examined the imprinting of the insulin-like growth factor II g ene (IGF2) in ten normal kidney samples from children with renal embry onal neoplasms. In kidney samples from nine children with normal growt h profiles, IGF2 mRNA was transcribed monoallelically, consistent with normal imprinting of the gene. But in one child who had generalized s omatic overgrowth, IGF2 was transcribed from both alleles in her kidne y, peripheral blood leukocytes and Wilms' tumour. These findings sugge st that a defect in genomic imprinting can occur constitutionally, lea ding to growth abnormalities and predisposition to Wilms' tumour.