GLUD1 and myalgic encephalomeyelitis/chronic fatigue syndrome: By contrast, Fluge et al. observed reductions in the levels of both glutamine and glutamate but also in the levels of aspartate, which may instead suggest increased glutamate degradation through the GLUD1 route, rather than through GOT2 as suggested by Armstrong et al. However, perhaps in contradiction to this, Fluge et al. also reported elevated sirtuin 4 (SIRT4) mRNA expression in ME/CFS PBMCs and SIRT4 is known to suppress GLUD1 activity [18].