In this context, the identification of specific infectious triggers, such as hepatitis C virus in our case, or drug-related factors, including therapies commonly used in the treatment of PV (such as anti-TNF-alpha agents like adalimumab or anti-IL-17 biologics such as secukinumab and ixekizumab), which have been associated with the onset of BP, may provide a crucial link between phenotype and genotype, contributing to the understanding of the pathogenic mechanisms involved. The gene discussed is IL17A; the disease is acquired polycythemia vera.