title: Deep Sequencing Reveals Novel Genetic Variants in Children with Acute Liver Failure and Tissue Evidence of Impaired Energy Metabolism.
abstract: OBJECTIVE
  The etiology of acute liver failure (ALF) remains elusive in almost half of affected children. We hypothesized that inherited mitochondrial and fatty acid oxidation disorders were occult etiological factors in patients with idiopathic ALF and impaired energy metabolism.
  
  
  METHODS
  Twelve patients with elevated blood molar lactate/pyruvate ratio and indeterminate etiology were selected from a retrospective cohort of 74 subjects with ALF because their fixed and frozen liver samples were available for histological, ultrastructural, molecular and biochemical analysis.
  
  
  RESULTS
  A customized next-generation sequencing panel for 26 genes associated with mitochondrial and fatty acid oxidation defects revealed mutations and sequence variants in five subjects. Variants involved the genes ACAD9, POLG, POLG2, DGUOK, and RRM2B; the latter not previously reported in subjects with ALF. The explanted livers of the patients with heterozygous, truncating insertion mutations in RRM2B showed patchy micro- and macrovesicular steatosis, decreased mitochondrial DNA (mtDNA) content <30% of controls, and reduced respiratory chain complex activity; both patients had good post-transplant outcome. One infant with severe lactic acidosis was found to carry two heterozygous variants in ACAD9, which was associated with isolated complex I deficiency and diffuse hypergranular hepatocytes. The two subjects with heterozygous variants of unknown clinical significance in POLG and DGUOK developed ALF following drug exposure. Their hepatocytes displayed abnormal mitochondria by electron microscopy.
  
  
  CONCLUSIONS
  Targeted next generation sequencing and correlation with histological, ultrastructural and functional studies on liver tissue in children with elevated lactate/pyruvate ratio expand the spectrum of genes associated with pediatric ALF.
authors.affiliation: Divisions of Human Genetics, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, United States of America.|Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America.
authors.forename: C Alexander
authors.initials: CA
authors.lastname: Valencia
authors.affiliation: Divisions of Human Genetics, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, United States of America.
authors.forename: Xinjian
authors.initials: X
authors.lastname: Wang
authors.affiliation: Divisions of Human Genetics, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, United States of America.
authors.forename: Jin
authors.initials: J
authors.lastname: Wang
authors.affiliation: Pediatric Gastroenterology, Hepatology and Nutrition, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, United States of America.
authors.forename: Anna
authors.initials: A
authors.lastname: Peters
authors.affiliation: Pediatric Gastroenterology, Hepatology and Nutrition, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, United States of America.
authors.forename: Julia R
authors.initials: JR
authors.lastname: Simmons
authors.affiliation: Pediatric Gastroenterology, Hepatology and Nutrition, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, United States of America.
authors.forename: Molly C
authors.initials: MC
authors.lastname: Moran
authors.affiliation: Divisions of Human Genetics, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, United States of America.
authors.forename: Abhinav
authors.initials: A
authors.lastname: Mathur
authors.affiliation: Divisions of Human Genetics, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, United States of America.
authors.forename: Ammar
authors.initials: A
authors.lastname: Husami
authors.affiliation: Divisions of Human Genetics, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, United States of America.
authors.forename: Yaping
authors.initials: Y
authors.lastname: Qian
authors.affiliation: Pediatric Pathology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, United States of America.
authors.forename: Rachel
authors.initials: R
authors.lastname: Sheridan
authors.affiliation: Pediatric Pathology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, United States of America.
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Bove
authors.affiliation: Pediatric Pathology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, United States of America.
authors.forename: David
authors.initials: D
authors.lastname: Witte
authors.affiliation: Divisions of Human Genetics, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, United States of America.|Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America.
authors.forename: Taosheng
authors.initials: T
authors.lastname: Huang
authors.affiliation: Pediatric Gastroenterology, Hepatology and Nutrition, Cincinnati Children's Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039, United States of America.|Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, United States of America.
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Miethke
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004272:DNA, Mitochondrial / Q000235:genetics; D004734:Energy Metabolism; D005260:Female; D014644:Genetic Variation; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008099:Liver / Q000378:metabolism / Q000473:pathology*; D017114:Liver Failure, Acute / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D009154:Mutation; D012189:Retrospective Studies
chemical_list: D004272:DNA, Mitochondrial