On the other hand, G6PT mutations underlie GSD-Ib, which implies either impaired metabolism as in GSD-Ia, or neutropenia and neutrophil dysfunction as in GSD-Irs (Chou et al., 2010a,b), even if in neutrophils and macrophages G6PT expression levels are rather low (Chou et al., 2013). The gene discussed is G6PC1; the disease is neutropenia.