The phenotype of the patient with a compound-heterozygous PMS2 germline mutation (the patient was previously described in Adam et al. [23]), was suggestive of CMMRD at the age of 15 years, however, on initial referral at the age of 9 years, the most likely differential diagnosis had been Li-Fraumeni syndrome. The gene discussed is PMS2; the disease is Li-Fraumeni syndrome.