title: 2-Methyl-3-hydroxybutyryl-CoA dehydrogenase deficiency is caused by mutations in the HADH2 gene.
abstract: 2-methyl-3-hydroxybutyryl-CoA dehydrogenase (MHBD) deficiency is a novel inborn error of isoleucine degradation. In this article, we report the elucidation of the molecular basis of MHBD deficiency. To this end, we purified the enzyme from bovine liver. MALDI-TOF mass spectrometry analysis revealed that the purified protein was identical to bovine 3-hydroxyacyl-CoA dehydrogenase type II. The human homolog of this bovine enzyme is a short-chain 3-hydroxyacyl-CoA dehydrogenase, also known as the "endoplasmic reticulum-associated amyloid-beta binding protein" (ERAB). This led to the identification of the X-chromosomal gene involved, which previously had been denoted "HADH2." Sequence analysis of the HADH2 gene from patients with MHBD deficiency revealed the presence of two missense mutations (R130C and L122V). Heterologous expression of the mutant cDNAs in Escherichia coli showed that both mutations almost completely abolish enzyme activity. This confirms that MHBD deficiency is caused by mutations in the HADH2 gene.
authors.affiliation: Department of Clinical Chemistry, Academic Medical Center, Emma Children's Hospital, University of Amsterdam, The Netherlands.
authors.forename: Rob
authors.initials: R
authors.lastname: Ofman
authors.forename: Jos P N
authors.initials: JP
authors.lastname: Ruiter
authors.forename: Marike
authors.initials: M
authors.lastname: Feenstra
authors.forename: Marinus
authors.initials: M
authors.lastname: Duran
authors.forename: Bwee Tien
authors.initials: BT
authors.lastname: Poll-The
authors.forename: Johannes
authors.initials: J
authors.lastname: Zschocke
authors.forename: Regina
authors.initials: R
authors.lastname: Ensenauer
authors.forename: Willy
authors.initials: W
authors.lastname: Lehnert
authors.forename: Jörn Oliver
authors.initials: JO
authors.lastname: Sass
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Sperl
authors.forename: Ronald J A
authors.initials: RJ
authors.lastname: Wanders
mesh_terms: D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000235:genetics* / Q000302:isolation & purification; D000429:Alcohol Oxidoreductases / Q000172:deficiency* / Q000235:genetics* / Q000302:isolation & purification; D019943:Amino Acid Substitution; D000818:Animals; D002417:Cattle; D004252:DNA Mutational Analysis; D005260:Female; D006801:Humans; D008099:Liver / Q000201:enzymology; D008297:Male; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D010375:Pedigree; D014960:X Chromosome / Q000235:genetics
chemical_list: D000429:Alcohol Oxidoreductases; D015094:3-Hydroxyacyl CoA Dehydrogenases; C419903:2-methyl-3-hydroxybutyryl-coenzyme A dehydrogenase; C108634:HSD17B10 protein, human; C458480:Hsd17b10 protein, mouse