title: Mitochondrial Complex III Deficiency with Ketoacidosis and Hyperglycemia Mimicking Neonatal Diabetes.
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 c1, 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.
authors.affiliation: Department of Medical Genetics, McGill University, 1001 Boulevard Décarie, Montréal, QC, Canada, H4A 3J1. natascia.anastasio@mail.mcgill.ca.
authors.forename: Natascia
authors.initials: N
authors.lastname: Anastasio
authors.affiliation: Centre for Molecular Medicine and Therapeutics, University of British Columbia, 950 West 28th Avenue, Vancouver, BC, Canada, V5Z 4H4.
authors.forename: Maja
authors.initials: M
authors.lastname: Tarailo-Graovac
authors.affiliation: Division of Pediatrics Endocrinology, McGill University, 1001 Boulevard Décarie, Montréal, QC, Canada, H4A 3J1.|Division of Pediatric Endocrinology, King Saud University, Riyadh, Saudi Arabia.
authors.forename: Reem
authors.initials: R
authors.lastname: Al-Khalifah
authors.affiliation: Division of Pediatrics Endocrinology, McGill University, 1001 Boulevard Décarie, Montréal, QC, Canada, H4A 3J1.
authors.forename: Laurent
authors.initials: L
authors.lastname: Legault
authors.affiliation: Child & Family Research Institute, University of British Columbia, 938 West 28th Avenue, Vancouver, BC, Canada, V5Z 4H4.
authors.forename: Britt
authors.initials: B
authors.lastname: Drogemoller
authors.affiliation: Child & Family Research Institute, University of British Columbia, 950 West 28th Avenue, A3-216, Vancouver, BC, Canada, V5Z 4H4.
authors.forename: Colin J D
authors.initials: CJ
authors.lastname: Ross
authors.affiliation: Department of Medical Genetics, Centre for Molecular Medicine and Therapeutics, Child & Family Research Institute, University of British Columbia, 950 West 28th Avenue, Vancouver, BC, Canada, V5Z 4H4.
authors.forename: Wyeth W
authors.initials: WW
authors.lastname: Wasserman
authors.affiliation: Department of Pediatrics, Centre for Molecular Medicine and Therapeutics, Child & Family Research Institute, University of British Columbia, 950 West 28th Avenue, Vancouver, BC, Canada, V5Z 4H4.
authors.forename: Clara
authors.initials: C
authors.lastname: van Karnebeek
authors.affiliation: Department of Medical Genetics, McGill University, 1001 Boulevard Décarie, Montréal, QC, Canada, H4A 3J1.
authors.forename: Daniela
authors.initials: D
authors.lastname: Buhas
keywords: CYC1 variant; Complex III; Neonatal diabetes; Whole-exome sequencing (WES)