In a typical morning in the Cancer Genetics Clinic at The Hospital for Sick Children in Toronto, the following array of patients and families might be seen: a family of three children, all harbouring a mutation of the succinyl dehydrogenase C gene inherited from their father who had had extensive surgery several years ago for a secreting paraganglioma; three families with Li-Fraumeni syndrome, each with at least one child harbouring a TP53 gene mutation conferring a lifetime risk of cancer approaching 100% and currently undergoing surveillance for early tumour detection; two children with Li-Fraumeni syndrome undergoing treatment for cancer - one having had three cancer diagnoses before 19 months of age and the other just completing therapy for metastatic adrenocortical carcinoma at age 3; two children with von Hippel-Lindau disease being monitored for persistent pancreatic neuroendocrine tumors and cerebellar hemangioblastomas, respectively; and one child with Beckwith-Wiedeman syndrome and Wilms tumor and another child completing therapy for a pleuropulmonary blastoma (PPB).