Certain genetic alterations are only observed in the context of specific cell or tissue types;34 for example, alterations in the APC gene in colorectal cancer, CDH1 (E‐cadherin) in gastric carcinoma, the VHL gene in renal carcinoma or BCR/ABL in leukaemia.35, 36 These specific genetic alterations demonstrate that tissue type plays a role, which is currently not well understood and is under intensive investigation. The gene discussed is CDH1; the disease is gastric carcinoma.