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The aetiology of neurological complications of organic acidaemias—A role for the blood–brain barrier

  • Hypothesis
  • Published:
Journal of Inherited Metabolic Disease


The blood–brain barrier (BBB) metabolically isolates the central nervous system (CNS) from the circulation and protects it against fluctuations of hydrophilic nutrients in plasma and from intoxication. Recent studies have shown that dicarboxylic acids (DCAs) are transported across the blood–brain barrier at very low rates. In organic acidaemias, neurological complications are common. We hypothesize that, as a result of the very limited efflux, in certain organic acidaemias there is pathological accumulation of DCAs (e.g. glutarate, 3-hydroxyglutarate, D-2- and L-2-hydroxyglutarate, methylmalonate) in the brain secondary to the metabolic block. At high concentrations some of these compounds may become neurotoxic. Treatment should be aimed at preventing the accumulation of these compounds using our understanding of the properties of the BBB.

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blood–brain barrier


central nervous system


cerebrospinal fluid


dicarboxylic acid


organic acid disorders


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Correspondence to J. V. Leonard.

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Communicating editor: Johannes Zschocke

Competing interests: None declared

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Kölker, S., Sauer, S.W., Surtees, R.A.H. et al. The aetiology of neurological complications of organic acidaemias—A role for the blood–brain barrier. J Inherit Metab Dis 29, 701–704 (2006).

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