Figure 1. Flow diagram of the analytical strategy.

Fifty nine unrelated families were screened for genetic defects in common MMR genes with all tests performed in parallel without using any sets of results for subsequent assays. Germline gene status was investigated by utilizing DNA extracted from blood or normal mucosa. Additional analyses in tumor tissues, such as immunohistochemical (IHC) assessment, microsatellite instability (MSI) test and mutation detection of BRAF V600E were performed where tumor materials were available. When a pathogenic or suspected deleterious defect was identified, family relatives were screened for presence of the same defect. ^†, at least one CRC patient each from 59 unrelated families.