An Integrated Mitochondrial Diagnostics Platform Combining Next-Generation Sequencing with Respiratory Studies in Patient Cells

Grant and Project Information

Date: April 2014

Award: $31,813 for one year. This amount is being matched by Children’s Hospital of Eastern Ontario for a total award of $63,625.

An Integrated Mitochondrial Diagnostics Platform Combining Next-Generation Sequencing with Respiratory Studies in Patient Cells  

Matthew A. Lines MD MSc(1), Dennis Bulman PhD(1,2), Pranesh Chakraborty MD(1,2), C. Anthony Rupar PhD(3,4), Martin Holcik PhD(2), Mary-Ellen Harper PhD(5)

  1. Metabolics and Newborn Screening, Children’s Hospital of Eastern Ontario, Ottawa, Canada
  2. Children’s Hospital of Eastern Ontario Research Institute, Ottawa, Canada
  3. Division of Clinical Biochemistry and Department of Pediatrics, University of Western Ontario,  London, ON, Canada
  4. Biochemical Genetics Laboratory, London Health Sciences Centre
  5. Biochemistry, Microbiology, and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Canada

Mitochondrial diseases represent a diverse group of genetic conditions that have traditionally proven difficult to diagnose, study, and treat due to their high degree of genetic heterogeneity. Although next-generation sequencing (NGS) easily permits the simultaneous sequencing of the >1000 known mitochondrial genes encoded across the nuclear and mitochondrial genomes, data interpretation is complicated by (i) the abundance of rare coding variants detected in any given individual, and (ii) a lack of knowledge regarding the functions and phenotypes of many mitochondrial genes. Early experience suggests that NGS-based testing will identify a known mitochondrial disease gene in up to ~25% of well selected probands; a further ~25% possess changes in novel candidate genes requiring functional assessment for validation of pathogenicity. In order to enhance the access of Canadians with mitochondrial diseases to this crucial technology, we have assembled a translational working group comprised of experts in clinical metabolics, NGS-based disease gene identification, and mitochondrial physiology/bioenergetics. We propose a translational pilot study of mitochondrial diagnosis via NGS, backed by a panel of functional assays in patient cells to assess respiration, mitochondrial morphology and dynamics, and cellular redox status. The incorporation of functional information will allow us to (i) corroborate, refute and/or refine clinical hypotheses suggested by NGS data, and (ii) assess the in vitro efficacy of various substrates, cofactors, and drugs on intact patient cells. The methodological insights gained during the study will support the establishment of a permanent diagnostic resource, and the data (novel disease genes) will serve as a launching pad for several further basic science projects. Data regarding the in vitro drug / cofactor response profile of each specific condition (gene) will be used to frame further studies of tailored therapy.