The international, consensus testing criteria for CDH1 germline mutations were recently revised in order to increase their performances, particularly their sensitivity. It is paramount to identify a high proportion of actual mutation carriers, as finding a mutation in a proband and subsequently in some of his relatives allows for risk-reducing recommendations regarding diffuse gastric cancer (DGC) and lobular breast cancer (LBC). We collected data on all French probands tested for CDH1 in a retrospective study on the hereditary DGC syndrome (HDGC). Out of 627 probands, 52 were carriers. We compared the new, 2015 version of these criteria to the 2010 version, and showed that both the sensitivity and the Youden index (J), an index that estimates the criteria discriminating power, increased.

CDH1 is a tumour suppressor gene located on chromosome 16q22. It codes for the E-cadherin adhesion protein. Monoallelic germline mutations in CDH1 cause HDGC, in which carriers have a high lifetime risk of DGC (also called signet ring cell gastric cancer), and LBC (reviewed in ref. 1). In clinical practice, mutations are first identified in a proband with a personal history of DGC and/or LBC, and adult relatives are subsequently tested to see whether they also carry the mutation. Asymptomatic carriers are then advised to undergo risk-reducing gastrectomy, and for women annual breast cancer screening using MRI. The International Gastric Cancer Linkage Consortium defined clinical criteria warranting CDH1 germline testing in a proband. The criteria were first published in 1999 and then updated in 2010.2 ,3 A new 2015 version is being published in this issue of the Journal of Medical Genetics …