<qa>  What is the percentage of nondiagnostic testing in suspected hereditary diffuse gastric cancer2. Individuals that have clinical suspicion for syndromic cancer susceptibility, but in whom mutational testing has been nondiagnostic depending on condition in question, nondiagnostic testing may be as little as 10, as in FAP, or as high as 70 in suspected hereditary diffuse gastric cancer or HDGC. 