GAPDH and congenital secretory chloride diarrhea 1: In this study, we used RT-qPCR to evaluate cfDII for ALU, LINE-1, β-actin, and GAPDH gene in healthy, CLD, and HCC patients as measures of cell-free DNA integrity (cfDII-integrity or L/S ratio) by absolute quantification methods and as measures of cell-free DNA fragmentation (cfDII-fragmentation) by relative quantification methods.