AICDA and colorectal carcinoma: Notably, although at low frequencies, we found that other signatures, such as Signature 9 (activity of AID during somatic hypermutation), Signature 8 (weak strand bias for C > A substitutions and unknown etiology), and Signature 16 (an extremely strong transcriptional strand bias for T > C mutations in the ApTpN context), were present in a certain fraction of patients (5.7%, 4.9%, and 2.6%, respectively), suggesting that other etiologies are responsible for the mutagenesis of CRC.