Lipoic acid synthetase deficiency causes neonatal-onset epilepsy, defective mitochondrial energy metabolism, and glycine elevation

Am J Hum Genet. 2011 Dec 9;89(6):792-7. doi: 10.1016/j.ajhg.2011.11.011.

Abstract

Lipoic acid is an essential prosthetic group of four mitochondrial enzymes involved in the oxidative decarboxylation of pyruvate, α-ketoglutarate, and branched chain amino acids and in the glycine cleavage. Lipoic acid is synthesized stepwise within mitochondria through a process that includes lipoic acid synthetase. We identified the homozygous mutation c.746G>A (p.Arg249His) in LIAS in an individual with neonatal-onset epilepsy, muscular hypotonia, lactic acidosis, and elevated glycine concentration in plasma and urine. Investigation of the mitochondrial energy metabolism showed reduced oxidation of pyruvate and decreased pyruvate dehydrogenase complex activity. A pronounced reduction of the prosthetic group lipoamide was found in lipoylated proteins.

Publication types

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

MeSH terms

  • Abnormalities, Multiple / diagnosis
  • Abnormalities, Multiple / enzymology
  • Abnormalities, Multiple / genetics*
  • Acidosis, Lactic / genetics
  • Amino Acid Sequence
  • Base Sequence
  • Chromosomes, Human, Pair 4
  • Consanguinity
  • Energy Metabolism / genetics*
  • Epilepsy / diagnosis
  • Epilepsy / enzymology
  • Epilepsy / genetics*
  • Escherichia coli / genetics
  • Escherichia coli / growth & development
  • Fatal Outcome
  • Fibroblasts / metabolism
  • Gene Expression
  • Glycine / blood*
  • Glycine / urine
  • Homozygote
  • Humans
  • Infant, Newborn
  • Infant, Newborn, Diseases / diagnosis
  • Infant, Newborn, Diseases / enzymology
  • Infant, Newborn, Diseases / genetics
  • Male
  • Mitochondria / enzymology
  • Mitochondria / metabolism*
  • Molecular Sequence Data
  • Muscle Hypotonia / genetics
  • Muscle, Skeletal / enzymology
  • Mutation, Missense
  • Pyruvate Dehydrogenase Complex / genetics
  • Pyruvate Dehydrogenase Complex / metabolism
  • Sequence Analysis, DNA
  • Sulfurtransferases / deficiency*

Substances

  • Pyruvate Dehydrogenase Complex
  • Sulfurtransferases
  • lipoic acid synthase
  • Glycine