Mitochondrial NADP(H) deficiency due to a mutation in NADK2 causes dienoyl-CoA reductase deficiency with hyperlysinemia.

Published

Journal Article

Dienoyl-CoA reductase (DECR) deficiency with hyperlysinemia is a rare disorder affecting the metabolism of polyunsaturated fatty acids and lysine. The molecular basis of this condition is currently unknown. We describe a new case with failure to thrive, developmental delay, lactic acidosis and severe encephalopathy suggestive of a mitochondrial disorder. Exome sequencing revealed a causal mutation in NADK2. NADK2 encodes the mitochondrial NAD kinase, which is crucial for NADP biosynthesis evidenced by decreased mitochondrial NADP(H) levels in patient fibroblasts. DECR and also the first step in lysine degradation are performed by NADP-dependent oxidoreductases explaining their in vivo deficiency. DECR activity was also deficient in lysates of patient fibroblasts and could only be rescued by transfecting patient cells with functional NADK2. Thus NADPH is not only crucial as a cosubstrate, but can also act as a molecular chaperone that activates and stabilizes enzymes. In addition to polyunsaturated fatty acid oxidation and lysine degradation, NADPH also plays a role in various other mitochondrial processes. We found decreased oxygen consumption and increased extracellular acidification in patient fibroblasts, which may explain why the disease course is consistent with clinical criteria for a mitochondrial disorder. We conclude that DECR deficiency with hyperlysinemia is caused by mitochondrial NADP(H) deficiency due to a mutation in NADK2.

Full Text

Duke Authors

Cited Authors

  • Houten, SM; Denis, S; Te Brinke, H; Jongejan, A; van Kampen, AHC; Bradley, EJ; Baas, F; Hennekam, RCM; Millington, DS; Young, SP; Frazier, DM; Gucsavas-Calikoglu, M; Wanders, RJA

Published Date

  • September 15, 2014

Published In

Volume / Issue

  • 23 / 18

Start / End Page

  • 5009 - 5016

PubMed ID

  • 24847004

Pubmed Central ID

  • 24847004

Electronic International Standard Serial Number (EISSN)

  • 1460-2083

Digital Object Identifier (DOI)

  • 10.1093/hmg/ddu218

Language

  • eng

Conference Location

  • England