Signatures associated with endogenous mutational processes were also found, including APOBEC (apolipoprotein B mRNA editing enzyme) cytidine deaminases (9.6% exposure), defective DNA mismatch repair (MMR deficiency) (26.7% exposure), and defective DNA Polymerase Epsilon (POLE deficiency) (13% exposure). This evidence concerns the gene CDA and mismatch repair cancer syndrome 1.