Adrenal pheochromocytoma, Anemia, Aniridia, Apnea, Arachnoid hemangiomatosis, Ataxia, Babinski sign, Blindness, CNS demyelination, Cerebral hemorrhage, Chest pain, Cognitive impairment, Conductive hearing impairment, Congestive heart failure, Constipation, Cranial nerve compression, Decreased activity of mitochondrial complex II, Decreased activity of mitochondrial respiratory chain, Decreased activity of the pyruvate dehydrogenase complex, Dementia, Developmental regression, Dilated cardiomyopathy, Distal amyotrophy, Dysarthria, Dysphagia, Dysphonia, Dystonia, EMG abnormality, Easy fatigability, Elevated calcitonin, Elevated circulating creatine kinase concentration, Elevated urinary dopamine, Elevated urinary epinephrine, Elevated urinary norepinephrine, Emotional lability, Episodic abdominal pain, Episodic hyperhidrosis, Episodic paroxysmal anxiety, Esophageal neoplasm, Exercise intolerance, Expressive language delay, External ophthalmoplegia, Extraadrenal pheochromocytoma, Failure to thrive, Fatigue, Feeding difficulties in infancy, Flexion contracture, Flushing, Focal T2 hyperintense basal ganglia lesion, Frequent falls, Gastrointestinal hemorrhage, Gastrointestinal stroma tumor, Generalized hypotonia, Generalized muscle weakness, Generalized myoclonic seizure, Gliosis, Global developmental delay, Glomerular sclerosis, Hearing impairment, Hematuria, Hemiplegia/hemiparesis, Hepatocellular necrosis, Hyperactive deep tendon reflexes, Hyperactive patellar reflex, Hypercalcemia, Hyperpigmentation of the skin, Hyperreflexia, Hyperreflexia in upper limbs, Hypertension associated with pheochromocytoma, Hypertensive retinopathy, Hypertrichosis, Hypertrophic cardiomyopathy, Hypotonia, Increased CSF lactate, Increased circulating lactate concentration, Increased intramyocellular lipid droplets, Intellectual disability, Intellectual disability, severe, Intestinal obstruction, Intrauterine growth retardation, Irregular hyperpigmentation, Irritability, Knee flexion contracture, Lactic acidosis, Large hands, Left ventricular hypertrophy, Left ventricular noncompaction, Leukodystrophy, Leukoencephalopathy, Lipoatrophy, Loss of ability to walk, Lower limb hypertonia, Mild microcephaly, Moderate global developmental delay, Motor delay, Motor deterioration, Muscle weakness, Myoclonus, Myopathy, Nausea, Nausea and vomiting, Neonatal hypotonia, Neoplasm of the colon, Neoplasm of the gastrointestinal tract, Neoplasm of the rectum, Neoplasm of the small intestine, Neoplasm of the stomach, Neurofibromas, Noncompaction cardiomyopathy, Nystagmus, Ophthalmoplegia, Optic atrophy, Pallor, Palmoplantar keratoderma, Palpitations, Panic attack, Paraganglioma, Paraganglioma of head and neck, Paroxysmal vertigo, Peripheral neuropathy, Pigmentary retinopathy, Poor head control, Positive regitine blocking test, Progressive cerebellar ataxia, Progressive leukoencephalopathy, Progressive ophthalmoplegia, Progressive psychomotor deterioration, Progressive spastic paraplegia, Proportionate short stature, Proteinuria, Proximal muscle weakness, Psychomotor retardation, Ptosis, Pulsatile tinnitus, Ragged-red muscle fibers, Recurrent paroxysmal headache, Reduced visual acuity, Renal cell carcinoma, Respiratory insufficiency, Retinal capillary hemangioma, Sarcoma, Seizure, Sensorineural hearing impairment, Severe short stature, Short stature, Sinus tachycardia, Skeletal muscle atrophy, Skeletal myopathy, Skin rash, Spastic paraparesis, Spastic tetraparesis, Spasticity, Strabismus, Stress/infection-induced lactic acidosis, Tremor, Urticaria, Ventricular septal defect, Vesicoureteral reflux, Visual impairment, Vocal cord paralysis, Weight loss, obsolete Segmental myoclonic seizures