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Thiamine pyrophosphokinase deficiency in encephalopathic children with defects in the pyruvate oxidation pathway

Johannes A Mayr1, Peter Freisinger, Kurt Schlachter

  • 1Department of Pediatrics, Paracelsus Medical University Salzburg, Salzburg, Austria. h.mayr@salk.at

American Journal of Human Genetics
|December 14, 2011
PubMed

Insights

Genetic defects in thiamine pyrophosphokinase (TPK) cause TPP deficiency, leading to neurological and metabolic disorders. Mutations in TPK1 result in reduced TPP levels and impaired mitochondrial function.

Area of Science:

  • Biochemistry
  • Genetics
  • Neuroscience

Background:

  • Thiamine pyrophosphate (TPP) is a crucial cofactor for key enzymes in cellular metabolism, including those involved in energy production.
  • Thiamine uptake and conversion to TPP by thiamine pyrophosphokinase (TPK) are essential for maintaining cellular TPP levels.

Observation:

  • Five individuals from three families presented with ataxia, psychomotor retardation, dystonia, and lactic acidosis.
  • Mitochondrial studies revealed reduced pyruvate oxidation despite normal pyruvate dehydrogenase complex activity when TPP was supplemented.
  • Reduced TPP concentrations were measured in muscle and blood samples.

Findings:

  • Genetic analysis identified three missense, one splice-site, and one frameshift mutation in the TPK1 gene.
  • These TPK1 mutations led to decreased TPK protein levels and consequently, reduced TPP concentrations.
  • The identified mutations establish a link between TPK1 dysfunction and impaired thiamine metabolism.

Implications:

  • This study identifies TPK1 mutations as a cause of a novel TPP-responsive metabolic disorder.
  • Understanding the role of TPK1 in TPP synthesis provides insights into the pathogenesis of neurological and metabolic diseases.
  • Genetic diagnosis of TPK1 mutations can enable early intervention and management of affected individuals.

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