Of considerable interest is the recent report of germline inactivating mutations within the CTR9 gene in three of 35 Wilms tumour families42, 43, and the report of the development of Wilms tumours in patients with germline inactivating CDC73 mutations (hyperthyroidism-jaw tumour syndrome, OMIM 145001) (refs 44, 45). The gene discussed is CTR9; the disease is hyperthyroidism.