Case Report

JIMD Reports, Volume 31

Volume 31 of the series JIMD Reports pp 57-62

Date:

Mitochondrial Complex III Deficiency with Ketoacidosis and Hyperglycemia Mimicking Neonatal Diabetes

  • Natascia AnastasioAffiliated withDepartment of Medical Genetics, McGill University Email author 
  • , Maja Tarailo-GraovacAffiliated withCentre for Molecular Medicine and Therapeutics, University of British Columbia
  • , Reem Al-KhalifahAffiliated withDivision of Pediatrics Endocrinology, McGill UniversityDivision of Pediatric Endocrinology, King Saud University
  • , Laurent LegaultAffiliated withDivision of Pediatrics Endocrinology, McGill University
  • , Britt DrogemollerAffiliated withChild & Family Research Institute, University of British Columbia
  • , Colin J.D. RossAffiliated withChild & Family Research Institute, University of British Columbia
  • , Wyeth W. WassermanAffiliated withDepartment of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child & Family Research Institute, University of British Columbia
  • , Clara van KarnebeekAffiliated withDepartment of Pediatrics, Centre for Molecular Medicine and Therapeutics, Child & Family Research Institute, University of British Columbia
  • , Daniela BuhasAffiliated withDepartment of Medical Genetics, McGill University

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Abstract

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.

Keywords

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