Unfortunately, guidelines for adjustment of IFN relating to neutropenia are unclear with three large studies failing to suggest a specific absolute neutrophil count values.6–7,9 The package insert of both PEG-IFN α-2a and α-2b recommend dose reduction for patients with neutrophil counts less than 750 cells/mm3 and drug discontinuation for those with counts less than 500 cells/mm3. The gene discussed is IFNA1; the disease is neutropenia.