Among the 26 variants identified by WES following the candidate gene approach, a literature search revealed that the APC, caspase 8, apoptosis-related cysteine peptidase (CASP8), ERBB2, MLH1, and PTPRJ gene variants have been previously investigated to verify their roles in cancer predisposition (see all the references in Additional file 7: Table S7). The gene discussed is PTPRJ; the disease is cancer.