title: Heterogeneity of mutations in maple syrup urine disease (MSUD): screening and identification of affected E1 alpha and E1 beta subunits of the branched-chain alpha-keto-acid dehydrogenase multienzyme complex.
abstract: Maple syrup urine disease (MSUD) is an autosomal recessive disease caused by a deficiency in subunits of the branched-chain alpha-keto-acid dehydrogenase complex (BCKDH). To characterize the mutations present in five patients with MSUD (four classic and one intermediate), three-step analyses were established: (1), identification of the involved subunit by complementation analysis using three different cell lines derived from homozygotes having E1 alpha, E1 beta or the E2 mutant gene; (2), screening for a mutation site in cDNA of the corresponding subunit by RT-PCR-SSCP and (3), mutant analysis by sequencing the amplified cDNA fragment. Four single-base missense mutations, R115W, Q146K [corrected], A209T and I282T, were detected in the E1 alpha subunit. A single-base missense mutation H156R and three frame-shift mutations to generate stop codons downstream, including an 11-bp deletion of the tandem repeat in exon 1, a single-base (T) deletion and a single-base (G) insertion, were identified in the E1 beta subunit gene. All except one (11-bp deletion in E1 beta (Nobukuni, Y., Mitsubuchi, H., Akaboshi, I., Indo, Y., Endo, F., Yoshioka, A. and Matsuda, I. (1991) J. Clin. Invest. 87, 1862-1866)) were novel mutations. The sites of amino-acid substitution were all conserved in other species. Thus, mutations causing MSUD are heterogenous.
authors.affiliation: Department of Pediatrics, Kumamoto University School of Medicine, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nobukuni
authors.forename: H
authors.initials: H
authors.lastname: Mitsubuchi
authors.forename: Y
authors.initials: Y
authors.lastname: Hayashida
authors.forename: K
authors.initials: K
authors.lastname: Ohta
authors.forename: Y
authors.initials: Y
authors.lastname: Indo
authors.forename: Y
authors.initials: Y
authors.lastname: Ichiba
authors.forename: F
authors.initials: F
authors.lastname: Endo
authors.forename: I
authors.initials: I
authors.lastname: Matsuda
mesh_terms: D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide); D001483:Base Sequence; D002459:Cell Fusion; D002460:Cell Line; D018076:DNA, Complementary / Q000235:genetics; D005816:Genetic Complementation Test; D006801:Humans; D007231:Infant, Newborn; D007658:Ketone Oxidoreductases / Q000737:chemistry / Q000235:genetics*; D008375:Maple Syrup Urine Disease / Q000201:enzymology / Q000235:genetics*; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry / Q000235:genetics*; D009154:Mutation; D010641:Phenotype
chemical_list: D018076:DNA, Complementary; D009097:Multienzyme Complexes; D007658:Ketone Oxidoreductases; D042942:3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)