An APOBEC3A hypermutation signature is distinguishable from the signature of background mutagenesis by APOBEC3B in human cancers

Dmitry Gordenin and colleagues use a yeast reporter strain to identify distinct mutagenic signatures for the cytosine deaminases APOBEC3A and APOBEC3B. They find that cancer samples with APOBEC3A-like mutation signatures have greater than tenfold more APOBEC signature mutations than those with APOBEC3B-like signatures.