MEN2A is characterised by the combined occurrence of medullary thyroid cancer (MTC) in association with phaeochromocytoma and PHPT.44,45 A genotype-phenotype correlation is observed such that the timing of MTC onset and likelihood of other clinical manifestations is related to the specific Ret Proto-Oncogene (RET) mutation. The gene discussed is RET; the disease is medullary thyroid gland carcinoma.