GBE1 encodes glycogen-branching enzyme 1, a critical enzyme in glycogen metabolism that catalyzes the transfer of alpha-1,4-linked glucose chains to create alpha-1,6-glucosidic branches 1. This branching increases glycogen polymer solubility and is essential for normal glycogen biosynthesis alongside glycogenin and glycogen synthase 1. Loss-of-function mutations in GBE1 cause glycogen storage disease type IV (GSD IV), an autosomal recessive disorder characterized by deficient branching enzyme activity and accumulation of poorly branched polyglucosan 2. GSD IV exhibits remarkable phenotypic heterogeneity, ranging from in utero/infantile presentations with hepatic, cardiac, and muscular involvement to adult polyglucosan body disease (APBD), a neurodegenerative condition featuring neurogenic bladder, spastic paraparesis, and peripheral neuropathy 2. Polyglucosan accumulation affects skeletal muscle, cardiac tissue, peripheral nerves, and white matter, causing myopathy and cardiomyopathy with arrhythmias and conduction abnormalities 3. Polyglucosan bodies are resistant to normal alpha-amylase digestion and appear fibrillar ultrastructurally, distinguishing them from typical glycogen 3. GBE1 has also been associated with brain imaging phenotypes in population studies 4. Beyond metabolic disease, GBE1 was recently implicated in pancreatic cancer progression through m6A-mediated regulation of cell proliferation 5.