Mitochondrial diseases mimicking neurotransmitter defects

Mitochondrion. 2008 Jun;8(3):273-8. doi: 10.1016/j.mito.2008.05.001. Epub 2008 May 21.


Objectives: Mitochondrial disorders are clinically heterogeneous. We aimed to describe 5 patients who presented with a clinical picture suggestive of primary neurotransmitter defects but who finally fulfilled diagnostic criteria for mitochondrial disease.

Methods: We report detailed clinical features, brain magnetic resonance findings and biochemical studies, including cerebrospinal fluid (CSF) biogenic amine and pterin measurements, respiratory chain enzyme activity, and molecular studies.

Results: The 5 patients had a very early onset age (from 1 day to 3 months) and a severe clinical course. They all showed a clinical picture suggestive of infantile hypokinetic-rigid syndrome (hypokinesia, hypomimia, slowness of reactions, tremor), other abnormal movements (myoclonus, dystonia), axial hypotonia, limb hypertonia, feeding difficulties, and psychomotor delay. Abnormal CSF findings among the 4 patients without treatment included low levels of homovanillic acid (HVA) in 3 patients, with associated low 5-hydroxyindoleacetic acid (5-HIAA) concentrations in two of them. Absent or mild and transitory improvement was observed after treatment with L-dopa. A diagnosis of mitochondrial disorder was finally made due to the appearance of hyperlactacidemia, diverse respiratory chain defects, and multisystemic involvement.

Conclusions: Secondary neurotransmitter disturbances may occur in mitochondrial diseases. Differential diagnosis of hypokinetic-rigid syndrome presenting in infancy could also include paediatric mitochondrial disorders.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alanine / blood
  • Brain / diagnostic imaging
  • Child, Preschool
  • Consanguinity
  • Diagnosis, Differential
  • Dopamine Agents / therapeutic use
  • Dystonia / diagnosis
  • Dystonia / diagnostic imaging
  • Dystonia / drug therapy*
  • Electron Transport Complex I / genetics
  • Electron Transport Complex I / metabolism
  • Electron Transport Complex II / genetics
  • Electron Transport Complex II / metabolism
  • Electron Transport Complex III / genetics
  • Electron Transport Complex III / metabolism
  • Female
  • Homovanillic Acid / cerebrospinal fluid
  • Humans
  • Hydroxyindoleacetic Acid / cerebrospinal fluid
  • Infant
  • Infant, Newborn
  • Lactic Acid / blood
  • Levodopa / therapeutic use
  • Male
  • Mitochondrial Diseases / cerebrospinal fluid
  • Mitochondrial Diseases / diagnosis*
  • Mitochondrial Diseases / pathology*
  • Neurotransmitter Agents / metabolism*
  • Pterins / analysis
  • Radiography
  • Treatment Outcome


  • Dopamine Agents
  • Neurotransmitter Agents
  • Pterins
  • Lactic Acid
  • Levodopa
  • Hydroxyindoleacetic Acid
  • Electron Transport Complex II
  • Electron Transport Complex I
  • Electron Transport Complex III
  • Alanine
  • Homovanillic Acid