- Probands with a diagnosis of gastric cancer who are in a family where there are no confirmed cases of diffuse type gastric adenocarcinoma (including the proband).
- Probands where there is evidence to suggest a Mismatch Repair (MMR) gene defect.
- Probands with ductal breast cancer
There is no evidence for CDH1 testing in the context of familial breast cancer where there is no family history of diffuse gastric cancer and/or lobular breast cancer.
Clinical predictive testing should never be ordered when only a variant of uncertain significance or polymorphism has been identified in a family.