Intriguingly, regarding the mechanism by which VGCV causes neutropenia, Billat et al. [50] investigated the association of a selected panel of membrane transporter polymorphisms and the evolution of neutrophil counts in 174 renal transplant recipients and found that a variant of ABCC4 (rs11568658) was associated with decreased neutrophil count following valganciclovir administration. The gene discussed is ABCC4; the disease is neutropenia.