Moreover, HEK293 cells transfected with this ABCC4 variant showed significantly increased intracellular ganciclovir accumulation in in vitro assays, and it was concluded that multidrug resistance-associated protein 4 (MRP4 = ABCC4) controls the intracellular accumulation of ganciclovir and contributes to ganciclovir-induced neutropenia in patients undergoing renal transplant. The gene discussed is ABCC4; the disease is neutropenia.