ATP1A3 and lactic acidosis: Patients may exhibit additional symptoms such as heart block, elevated cerebrospinal fluid protein levels, ataxia, deafness, cognitive delays, and hormonal imbalances.[6] Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes typically appear in children or young adults with recurring episodes of encephalopathy, myopathy, headaches, and progressive focal neurological deficits.[7] When differentiating AHC, it is also important to consider other ATP1A3-related disorders, such as early-onset infantile epileptic encephalopathy and rapid-onset dystonia parkinsonism.