Table 2. Dietary interventions.
| Disorder | Cause (gene) | Movement disorder | Other clinical features2 | Treatment | Outcome |
|---|---|---|---|---|---|
| Abetalipoproteinemia (Bassen-Kornzweig) | Microsomal triglyceride transfer protein (mttp) | Ataxia, chorea, dystonia, parkinsonism | Retinitis pigmentosa, dementia, seizures, acanthocytosis, fat malabsorption | Dietary fat restriction, vitamins E & A | Early treatment prevents symptoms26 |
| Cerebral creatine deficiency | Creatine synthesis (GAMT, AGAT) | Chorea, dystonia, ataxia | Developmental delay, epilepsy, behavioral deficits, myopathy | Creatine ± ornithine and dietary restriction of arginine | Partial improvement of symptoms35 |
| GLUT1 deficiency | Glucose transporter (GLUT1) | Paroxysmal or chronic dystonia, ataxia, chorea, myoclonus | Developmental delay, seizures, alternating hemiplegia | Ketogenic diet, triheptanoin | Treatment reduces symptoms50,84 |
| Glutaric aciduria type 1 | Glutaryl Co-A dehydrogenase (GCDH) | Dystonia, parkinsonism | Developmental delay, encephalopathic crises (often triggered by metabolic decompensation) | Avoid or treat triggers, dietary lysine restriction, L-carnitine | Treatment mitigates long-term deficits42,43 |
| Homocystinuria | Cystathione beta synthase (CBS) | Dystonia, parkinsonism | Developmental delay, myopia, ectopic lens, psychiatric features | Vitamin B6, dietary restriction of methionine, betaine | Early treatment prevents most symptoms22 |
| Maple syrup urine disease | Branched chain alpha-ketoacid dehydrogenase complex (BCKDHA, BCKDHB, DBT) | Dystonia, tremor, ataxia (may be paroxysmal) | Developmental delay, episodic encephalopathy (often triggered by metabolic decompensation) | Avoid or treat triggers; dietary leucine restriction | Treatment mitigates episodes85 |
| Methylmalonic aciduria | Methylmalonyl Co-A mutase (MUT) | Dystonia, chorea | Developmental delay, auditory impairment, encephalopathic crises (often triggered by metabolic decompensation) | Avoid or treat triggers; dietary protein restriction, L-carnitine | Treatment may attenuate crises44 |
| Phenylketonuria | Phenylalanine hydroxylase (PAH) | Parkinsonism, spasticity | Intellectual disabililty | Dietary restriction of phenylalanine | Early treatment prevents most symptoms21 |
| Propionic acidemia | Propionyl Co-A carboxylase (PCCA, PCCB) | Dystonia, chorea | Developmental delay, encephalopathic crisis, seizures optic atrophy (often triggered by metabolic decompensation) | Avoid or treat triggers, dietary protein restriction, L-carnitine | Treatment prevents or mitigates symptoms44 |
| Pyruvate dehydrogenase complex deficiency | Pyruvate dehydrogenase complex (multiple genes) | Chronic or paroxysmal dystonia, ataxia | Developmental delay, encephalopathy, seizures | Thiamine, ketogenic diet, triheptanoin | Treatment mitigates symptoms29,30 |
| Refsum disease | Phytanyl Co-A hydroxylase (PHYH) | Ataxia | Retinitis pigmentosa, neuropathy, auditory impairment, skin changes | Dietary restriction of phytanic acids, plasmapheresis | Complete or partial prevention or reduction of symptoms24,25 |
Many of these disorders have variable or mixed phenotypes. The most common or most dominant movement disorders are shown in boldface type. The term metabolic decompensation refers to a state in which the body's consumption of a metabolite (eg, energy) exceeds supply.