Neutropenia and neutrophil dysfunction in GSD type 1b and SCN-4 were recently shown to be the result of 1,5-anhydroglucitol-6-phosphate (1,5AG6P) accumulation in granulocytes caused by the loss of G6PT1 or G6PC3 that normally collaborate to destroy this metabolite. This evidence concerns the gene G6PC3 and neutropenia.