Most of the solid cancers arising in the childhood develop from embryonic tissues. The frequent association of paediatric cancers and abnormalities of the development underlines the link between oncogenesis and embryogenesis. However, beside the known malformative syndromes predisposing to one or several types of tumours with a variable penetrance (NF1, Wiedemann-Beckwith, Denys-Drash, Fanconi disease), associations between abnormalities of the development and tumours are badly known and little investigated, and are not listed at present systematically in the registers of child cancers.