These challenges may underlie second hit detection in the VUS cases tested in this study where, for example, the EC from person ID_156 who carried the MSH6 c.3556 + 5_3556 + 9delins variant and CRC from person ID_376 who carried the MSH2 exon 1-6 duplication did not identify a second hit despite the other cumulative evidence suggesting these variants are likely pathogenic. Here, MSH2 is linked to colorectal carcinoma.