These observations suggest that APOBEC3A/B editing rates vary between individuals in the context of BKPyV infection, and this may constitute a risk factor for the development of urothelial carcinoma subsequent to BKPyV infection, due to the role of APOBEC3A/B as a major mutagen in this cancer [37,38]. The gene discussed is APOBEC3A; the disease is urothelial carcinoma.