A summary of testing approach and outcomes and the final classification of each SLS case from the germline whole-genome sequencing (WGS) and tumor-sequencing analyses in this study. †SLS2: kidney tumor (T2A) failed tumor sequencing. ‡Additional tumor WGS information: no MMR deficiency–related mutational signatures, microsatellite stable by microsatellite instability sensor, tumor mutation burden not considered hypermutated; therefore, tumor not considered to have MMR deficiency and likely false-positive loss of MSH6 expression on IHC. ACCFR, Australasian Colorectal Cancer Family Registry; ANECS, Australian National Endometrial Cancer Study.