We were additionally surprised to find that A3B-null tumours with one copy of A3H-I (A3H-I/II or I/III) or two copies of A3H-I showed remarkably strong APOBEC signatures (boxed in Fig. 1d with statistical significance for non-A3H-I versus A3H-I mutation proportion comparisons in Supplementary Table 1). Here, APOBEC3B is linked to neoplasm.