Glycogen hyperphosphorylation results in PGBs that impact glycogen turnover, and perturbations in this process have deleterious consequences as mutations in the gene encoding laforin result in the fatal childhood dementia and progressive myoclonus epilepsy Lafora disease (Turnbull et al, 2016; Gentry et al, 2018). Here, EPM2A is linked to childhood-onset dementia.