Mitochondrial Complex III Deficiency with Ketoacidosis and Hyperglycemia Mimicking Neonatal Diabetes

  • Natascia AnastasioEmail author
  • Maja Tarailo-Graovac
  • Reem Al-Khalifah
  • Laurent Legault
  • Britt Drogemoller
  • Colin J.D. Ross
  • Wyeth W. Wasserman
  • Clara van Karnebeek
  • Daniela Buhas
Case Report
Part of the JIMD Reports book series (JIMD, volume 31)


Hyperglycemia is a rare presenting symptom of mitochondrial disorders. We report a case of a young girl who presented shortly after birth with ketoacidosis, hyperlactatemia, hyperammonemia, and insulin-responsive hyperglycemia. Initial metabolic work-up suggested mitochondrial dysfunction. Given our patient’s unusual presentation, whole-exome sequencing (WES) was performed on the parent–offspring trio. The patient was homozygous for the c.643C>T (p.Leu215Phe) variant in CYC1, a nuclear gene which encodes cytochrome c 1 , a subunit of respiratory chain complex III. Variants in this gene have only been previously reported in two patients with similar presentation, one of whom carries the same variant as our patient who is also of Sri Lankan origin.

Primary complex III deficiencies are rare and its phenotypes can vary significantly, even among patients with the same genotype.


Complex III CYC1 variant Neonatal diabetes Whole-exome sequencing (WES) 



We gratefully acknowledge the family for their participation in this study; Mrs. X. Han for Sanger sequencing; Mr. B. Sayson and Ms A. Ghani for consenting and data management; and Mrs. M. Higginson for DNA extraction, sample handling, and technical data (University of British Columbia, Vancouver, CA).


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Copyright information

© SSIEM and Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  • Natascia Anastasio
    • 1
    Email author
  • Maja Tarailo-Graovac
    • 2
  • Reem Al-Khalifah
    • 3
    • 4
  • Laurent Legault
    • 3
  • Britt Drogemoller
    • 5
  • Colin J.D. Ross
    • 6
  • Wyeth W. Wasserman
    • 7
  • Clara van Karnebeek
    • 8
  • Daniela Buhas
    • 1
  1. 1.Department of Medical GeneticsMcGill UniversityMontréalCanada
  2. 2.Centre for Molecular Medicine and Therapeutics, University of British ColumbiaVancouverCanada
  3. 3.Division of Pediatrics EndocrinologyMcGill UniversityMontréalCanada
  4. 4.Division of Pediatric EndocrinologyKing Saud UniversityRiyadhSaudi Arabia
  5. 5.Child & Family Research Institute, University of British ColumbiaVancouverCanada
  6. 6.Child & Family Research Institute, University of British ColumbiaVancouverCanada
  7. 7.Department of Medical GeneticsCentre for Molecular Medicine and Therapeutics, Child & Family Research Institute, University of British ColumbiaVancouverCanada
  8. 8.Department of PediatricsCentre for Molecular Medicine and Therapeutics, Child & Family Research Institute, University of British ColumbiaVancouverCanada

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