Journal of Inherited Metabolic Disease

, Volume 30, Issue 2, pp 248–255 | Cite as

Xanthurenic aciduria due to a mutation in KYNU encoding kynureninase

  • M. Christensen
  • M. Duno
  • A. M. Lund
  • F. Skovby
  • E. Christensen
Original Article


Massive urinary excretion of xanthurenic acid, 3-hydroxykynurenine and kynurenine, known as xanthurenic aciduria or hydroxykynureninuria, in a young Somali boy suggested kynureninase deficiency. Mutation analysis of KYNU encoding kynureninase of the index case revealed homozygosity for a c.593 A > G substitution leading to a threonine-to-alanine (T198A) shift. A younger brother was found to have a similar excretion pattern and the same genotype. At present, neither of the two boys has symptoms of niacin deficiency. This is the first report linking xanthurenic aciduria to a mutation in the gene encoding kynureninase.



3-hydroxyanthranilic acid




anthranilic acid


internal standard




kynurenic acid


xanthurenic acid


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Copyright information

© SSIEM and Springer 2007

Authors and Affiliations

  • M. Christensen
    • 1
  • M. Duno
    • 1
  • A. M. Lund
    • 1
  • F. Skovby
    • 1
  • E. Christensen
    • 1
  1. 1.Department of Clinical GeneticsRigshospitalet 4062CopenhagenDenmark

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