title: Molecular diagnosis of infantile mitochondrial disease with targeted next-generation sequencing.
abstract: Advances in next-generation sequencing (NGS) promise to facilitate diagnosis of inherited disorders. Although in research settings NGS has pinpointed causal alleles using segregation in large families, the key challenge for clinical diagnosis is application to single individuals. To explore its diagnostic use, we performed targeted NGS in 42 unrelated infants with clinical and biochemical evidence of mitochondrial oxidative phosphorylation disease. These devastating mitochondrial disorders are characterized by phenotypic and genetic heterogeneity, with more than 100 causal genes identified to date. We performed "MitoExome" sequencing of the mitochondrial DNA (mtDNA) and exons of ~1000 nuclear genes encoding mitochondrial proteins and prioritized rare mutations predicted to disrupt function. Because patients and healthy control individuals harbored a comparable number of such heterozygous alleles, we could not prioritize dominant-acting genes. However, patients showed a fivefold enrichment of genes with two such mutations that could underlie recessive disease. In total, 23 of 42 (55%) patients harbored such recessive genes or pathogenic mtDNA variants. Firm diagnoses were enabled in 10 patients (24%) who had mutations in genes previously linked to disease. Thirteen patients (31%) had mutations in nuclear genes not previously linked to disease. The pathogenicity of two such genes, NDUFB3 and AGK, was supported by complementation studies and evidence from multiple patients, respectively. The results underscore the potential and challenges of deploying NGS in clinical settings.
authors.affiliation: Center for Human Genetic Research and Department of Molecular Biology, Massachusetts General Hospital, 185 Cambridge Street, Sixth Floor, Boston, MA 02114, USA.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Calvo
authors.forename: Alison G
authors.initials: AG
authors.lastname: Compton
authors.forename: Steven G
authors.initials: SG
authors.lastname: Hershman
authors.forename: Sze Chern
authors.initials: SC
authors.lastname: Lim
authors.forename: Daniel S
authors.initials: DS
authors.lastname: Lieber
authors.forename: Elena J
authors.initials: EJ
authors.lastname: Tucker
authors.forename: Adrienne
authors.initials: A
authors.lastname: Laskowski
authors.forename: Caterina
authors.initials: C
authors.lastname: Garone
authors.forename: Shangtao
authors.initials: S
authors.lastname: Liu
authors.forename: David B
authors.initials: DB
authors.lastname: Jaffe
authors.forename: John
authors.initials: J
authors.lastname: Christodoulou
authors.forename: Janice M
authors.initials: JM
authors.lastname: Fletcher
authors.forename: Damien L
authors.initials: DL
authors.lastname: Bruno
authors.forename: Jack
authors.initials: J
authors.lastname: Goldblatt
authors.forename: Salvatore
authors.initials: S
authors.lastname: Dimauro
authors.forename: David R
authors.initials: DR
authors.lastname: Thorburn
authors.forename: Vamsi K
authors.initials: VK
authors.lastname: Mootha
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D016022:Case-Control Studies; D002467:Cell Nucleus / Q000235:genetics; D002648:Child; D002675:Child, Preschool; D004272:DNA, Mitochondrial / Q000235:genetics; D042967:Electron Transport Complex I / Q000235:genetics; D059472:Exome / Q000235:genetics; D005260:Female; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D050259:Genes, Mitochondrial / Q000235:genetics; D056726:Genetic Association Studies; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D028361:Mitochondrial Diseases / Q000175:diagnosis* / Q000201:enzymology / Q000235:genetics*; D017240:Mitochondrial Myopathies / Q000235:genetics; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010085:Oxidative Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000737:chemistry / Q000235:genetics; D015203:Reproducibility of Results; D017422:Sequence Analysis, DNA / Q000379:methods*
chemical_list: D004272:DNA, Mitochondrial; C492429:AGK protein, human; D017853:Phosphotransferases (Alcohol Group Acceptor); D042967:Electron Transport Complex I