Abnormal activity of mitochondrial respiratory chain, Abnormal emotion/affect behavior, Abnormality of acid-base homeostasis, Abnormality of amino acid metabolism, Abnormality of body weight, Abnormality of carboxylic acid metabolism, Abnormality of cell physiology, Abnormality of central motor function, Abnormality of circulating enzyme level, Abnormality of circulating protein level, Abnormality of eye movement, Abnormality of facial musculature, Abnormality of facial soft tissue, Abnormality of head and neck, Abnormality of higher mental function, Abnormality of metabolism/homeostasis, Abnormality of mitochondrial metabolism, Abnormality of movement, Abnormality of muscle physiology, Abnormality of pyramidal motor function, Abnormality of the basal ganglia, Abnormality of the central nervous system, Abnormality of the cerebral subcortex, Abnormality of the cerebrum, Abnormality of the cranial nerves, Abnormality of the ear, Abnormality of the eye, Abnormality of the face, Abnormality of the forebrain, Abnormality of the genitourinary system, Abnormality of the head, Abnormality of the inner ear, Abnormality of the mitochondrion, Abnormality of the musculature, Abnormality of the nervous system, Abnormality of the peripheral nervous system, Abnormality of the respiratory system, Abnormality of the seventh cranial nerve, Abnormality of the urinary system, Abnormality of the urinary system physiology, Abnormality of the vitamin B12 metabolism, Abnormality of urine homeostasis, Abnormality of vitamin B metabolism, Abnormality of vitamin metabolism, Abnormal muscle tone, Acidosis, Aciduria, Age of onset, All, Aminoaciduria, Aplasia/Hypoplasia involving the central nervous system, Athetosis, Atrophy/Degeneration affecting the central nervous system, Atrophy/Degeneration affecting the cerebrum, Autosomal recessive inheritance, Behavioural/Psychiatric Abnormality, Cerebral atrophy, Cognitive impairment, Cranial nerve paralysis, Decreased activity of mitochondrial respiratory chain, Decreased body weight, Delayed gross motor development, Dystonia, Elevated serum creatine phosphokinase, Encephalopathy, Facial diplegia, Facial palsy, Failure to thrive, Functional abnormality of the inner ear, Functional respiratory abnormality, Gait disturbance, Global developmental delay, Growth abnormality, Hearing abnormality, Hearing impairment, Hypertonia, Hyporeflexia, Inability to walk, Inability to walk by childhood/adolescence, Infantile onset, Intellectual disability, Intellectual disability, progressive, Involuntary movements, Irritability, Lactic acidosis, Loss of ability to walk in early childhood, Methylmalonic acidemia, Mode of inheritance, Morphological abnormality of the central nervous system, Motor delay, Muscle weakness, Muscular hypotonia, Onset, Onset and clinical course, Ophthalmoparesis, Ophthalmoplegia, Peripheral neuropathy, Phenotypic abnormality, Progressive encephalopathy, Progressive inability to walk, Ptosis, Reduced tendon reflexes, Respiratory insufficiency due to muscle weakness, Seizures, Sensorineural hearing impairment, Spasticity, Strabismus, Weakness of muscles of respiration.