CSTB and lactic acidosis: Genetics: The patient underwent different molecular investigations that excluded Lafora disease (laforin—EPM2A and malin—NHLRC1), Unverricht–Lundborg disease (cystatin B, CSTB), myoclonic epilepsy with ragged red fibers (MERFF), mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), ceroid lipofuscinoses, hereditary ataxias, opsoclonus–myoclonus paraneoplastic syndrome, Kinsbourne disease, and Ramsay–Hunt disease.