title: Clinical and biochemical characterization of four patients with mutations in ECHS1.
abstract: BACKGROUND
  Short-chain enoyl-CoA hydratase (SCEH, encoded by ECHS1) catalyzes hydration of 2-trans-enoyl-CoAs to 3(S)-hydroxy-acyl-CoAs. SCEH has a broad substrate specificity and is believed to play an important role in mitochondrial fatty acid oxidation and in the metabolism of branched-chain amino acids. Recently, the first patients with SCEH deficiency have been reported revealing only a defect in valine catabolism. We investigated the role of SCEH in fatty acid and branched-chain amino acid metabolism in four newly identified patients. In addition, because of the Leigh-like presentation, we studied enzymes involved in bioenergetics.
  
  
  METHODS
  Metabolite, enzymatic, protein and genetic analyses were performed in four patients, including two siblings. Palmitate loading studies in fibroblasts were performed to study mitochondrial β-oxidation. In addition, enoyl-CoA hydratase activity was measured with crotonyl-CoA, methacrylyl-CoA, tiglyl-CoA and 3-methylcrotonyl-CoA both in fibroblasts and liver to further study the role of SCEH in different metabolic pathways. Analyses of pyruvate dehydrogenase and respiratory chain complexes were performed in multiple tissues of two patients.
  
  
  RESULTS
  All patients were either homozygous or compound heterozygous for mutations in the ECHS1 gene, had markedly reduced SCEH enzymatic activity and protein level in fibroblasts. All patients presented with lactic acidosis. The first two patients presented with vacuolating leukoencephalopathy and basal ganglia abnormalities. The third patient showed a slow neurodegenerative condition with global brain atrophy and the fourth patient showed Leigh-like lesions with a single episode of metabolic acidosis. Clinical picture and metabolite analysis were not consistent with a mitochondrial fatty acid oxidation disorder, which was supported by the normal palmitate loading test in fibroblasts. Patient fibroblasts displayed deficient hydratase activity with different substrates tested. Pyruvate dehydrogenase activity was markedly reduced in particular in muscle from the most severely affected patients, which was caused by reduced expression of E2 protein, whereas E2 mRNA was increased.
  
  
  CONCLUSIONS
  Despite its activity towards substrates from different metabolic pathways, SCEH appears to be only crucial in valine metabolism, but not in isoleucine metabolism, and only of limited importance for mitochondrial fatty acid oxidation. In severely affected patients SCEH deficiency can cause a secondary pyruvate dehydrogenase deficiency contributing to the clinical presentation.
authors.affiliation: Departments of Clinical Chemistry and Pediatrics, Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, AZ, 1105, The Netherlands. s.ferdinandusse@amc.nl.
authors.forename: Sacha
authors.initials: S
authors.lastname: Ferdinandusse
authors.affiliation: Department of Pediatrics, Section of Genetics, University of Colorado, Aurora, CO, 80045, USA. Marisa.Friederich@ucdenver.edu.
authors.forename: Marisa W
authors.initials: MW
authors.lastname: Friederich
authors.affiliation: Department of Paediatrics, Division of Metabolic Diseases, University Hospital of Padua, Padua, Italy. alberto.burlina@unipd.it.
authors.forename: Alberto
authors.initials: A
authors.lastname: Burlina
authors.affiliation: Departments of Clinical Chemistry and Pediatrics, Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, AZ, 1105, The Netherlands. j.ruiter@amc.uva.nl.
authors.forename: Jos P N
authors.initials: JP
authors.lastname: Ruiter
authors.affiliation: Department of Pediatrics, Section of Genetics, University of Colorado, Aurora, CO, 80045, USA. Curtis.Coughlin@childrenscolorado.org.
authors.forename: Curtis R
authors.initials: CR
authors.lastname: Coughlin
authors.affiliation: Department of Pathology, University of Colorado, Aurora, CO, 80045, USA. megan.dishop@childrensmn.org.
authors.forename: Megan K
authors.initials: MK
authors.lastname: Dishop
authors.affiliation: Department of Pediatrics, Section of Genetics, University of Colorado, Aurora, CO, 80045, USA. Renata.Gallagher@ucsf.edu.
authors.forename: Renata C
authors.initials: RC
authors.lastname: Gallagher
authors.affiliation: Center for Inherited Disorders of Energy Metabolism (CIDEM), University Hospitals Case Medical Center, Cleveland, OH, 44106, USA. Jirair.Bedoyan@UHhospitals.org.|Departments of Genetics and Pediatrics, Case Western Reserve University, Cleveland, OH, 44106, USA. Jirair.Bedoyan@UHhospitals.org.
authors.forename: Jirair K
authors.initials: JK
authors.lastname: Bedoyan
authors.affiliation: Departments of Clinical Chemistry and Pediatrics, Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, AZ, 1105, The Netherlands. f.m.vaz@amc.nl.
authors.forename: Frédéric M
authors.initials: FM
authors.lastname: Vaz
authors.affiliation: Departments of Clinical Chemistry and Pediatrics, Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, AZ, 1105, The Netherlands. h.r.waterham@amc.nl.
authors.forename: Hans R
authors.initials: HR
authors.lastname: Waterham
authors.affiliation: Department of Biochemistry and Molecular Genetics, University of Colorado, Aurora, CO, 80045, USA. Katherine.Gowan@ucdenver.edu.
authors.forename: Katherine
authors.initials: K
authors.lastname: Gowan
authors.affiliation: Department of Pediatrics, Section of Genetics, University of Colorado, Aurora, CO, 80045, USA. Kathryn.Chatfield@ucdenver.edu.|Department of Pediatrics, Section of Pediatric Cardiology, University of Colorado, Aurora, CO, 80045, USA. Kathryn.Chatfield@ucdenver.edu.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Chatfield
authors.affiliation: Department of Pathology & Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, U74SA, USA. kormanikk@email.chop.edu.
authors.forename: Kaitlyn
authors.initials: K
authors.lastname: Bloom
authors.affiliation: Department of Pathology & Laboratory Medicine, Children's Hospital of Philadelphia and Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, U74SA, USA. bennettmi@email.chop.edu.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Bennett
authors.affiliation: Monique and Jacques Roboh Department of Genetic Research, Hadassah, Hebrew University Medical Center, Jerusalem, Israel. elpeleg@hadassah.org.il.
authors.forename: Orly
authors.initials: O
authors.lastname: Elpeleg
authors.affiliation: Department of Pediatrics, Section of Genetics, University of Colorado, Aurora, CO, 80045, USA. Johan.VanHove@childrenscolorado.org.
authors.forename: Johan L K
authors.initials: JL
authors.lastname: Van Hove
authors.affiliation: Departments of Clinical Chemistry and Pediatrics, Laboratory Genetic Metabolic Diseases, Academic Medical Center, University of Amsterdam, Amsterdam, AZ, 1105, The Netherlands. r.j.wanders@amc.nl.
authors.forename: Ronald J A
authors.initials: RJ
authors.lastname: Wanders
mesh_terms: D000214:Acyl Coenzyme A / Q000172:deficiency / Q000235:genetics*; D002648:Child; D004746:Enoyl-CoA Hydratase / Q000235:genetics; D005260:Female; D006579:Heterozygote; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007888:Leigh Disease / Q000175:diagnosis / Q000209:etiology / Q000235:genetics; D008297:Male; D009154:Mutation
chemical_list: D000214:Acyl Coenzyme A; C033618:tiglyl-coenzyme A; C010701:crotonyl-coenzyme A; D004746:Enoyl-CoA Hydratase