E2 transacylase-deficient (type II) maple syrup urine disease: Aberrant splicing of E2 mRNA caused by internal intronic deletions and association with thiamine-responsive phenotype

Jacinta L. Chuang, Body P. Cox, David T. Chuang

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

Maple syrup urine disease (MSUD) or branched-chain α-keto-aciduria is an autosomally inherited disorder in the catabolism of branched-chain amino acids leucine, isoleucine, and valine. The disease is characterized by severe ketoacidosis, mental retardation, and neurological impairments. MSUD can be classified into genetic subtypes according to the genes of the branched- chain α-ketoacid dehydrogenase (BCKD) complex which are affected in patients. We describe here four intronic deletions and an intronic nucleotide substitution in the E2 transacylase gene of type II MSUD, in which the E2 subunit of the BCKD complex is deficient. These new E2 mutations comprise an internal 3.2-kb deletion in intron 4 (causing a 17-bp insertion in mRNA), an internal 12-bp (ttaccttgttac) deletion in intron 4 (creating a 10-bp insertion), a 10-bp (catttctaG) deletion in intron 10/exon 11 junction (leading to a 21-bp deletion), a 2-bp deletion in the exon 5/intron 5 junction (ATgt→A-t) (resulting in the skipping of exon 5), and a G to A transition at nucleotide -7 of intron 9 (causing a 6-bp insertion). These intronic mutations were initially detected by secondary alterations in the mutant E2 mRNA, as a result of aberrant splicing. The 3.2-kb deletion in intron 4 was determined by the amplification of the entire intron from both a normal subject (11.2 kb) and a homozygous patient (8 kb) by long PCR, followed by subcloning and sequencing of regions flanking the deletion. Similar methods were used to identify and characterize the other intronic alterations. Our results depict heretofore undescribed splicing errors caused by the deletion of internal intronic segments, and provide an approach for detecting this class of novel and rare human mutation. The association of the thiamine-responsive phenotype with a subset of the type II MSUD patients studied is also discussed.

Original languageEnglish (US)
Pages (from-to)736-744
Number of pages9
JournalJournal of Clinical Investigation
Volume100
Issue number3
StatePublished - Aug 1 1997

Fingerprint

Thiamine
Introns
Phenotype
Messenger RNA
3-Methyl-2-Oxobutanoate Dehydrogenase (Lipoamide)
Maple Syrup Urine Disease
Exons
Mutation
Nucleotides
Branched Chain Amino Acids
Ketosis
Isoleucine
Valine
dihydrolipoamide acyltransferase
Type 2 Maple syrup urine disease
Leucine
Intellectual Disability
Genes
Polymerase Chain Reaction

Keywords

  • Branched-chain α-ketoacid dehydrogenase complex
  • Cryptic splice site activation
  • Exon skipping
  • New splice site creation
  • Secondary insertions/deletions

ASJC Scopus subject areas

  • Medicine(all)

Cite this

@article{c5298b782667453bae8451de5f1ffae1,
title = "E2 transacylase-deficient (type II) maple syrup urine disease: Aberrant splicing of E2 mRNA caused by internal intronic deletions and association with thiamine-responsive phenotype",
abstract = "Maple syrup urine disease (MSUD) or branched-chain α-keto-aciduria is an autosomally inherited disorder in the catabolism of branched-chain amino acids leucine, isoleucine, and valine. The disease is characterized by severe ketoacidosis, mental retardation, and neurological impairments. MSUD can be classified into genetic subtypes according to the genes of the branched- chain α-ketoacid dehydrogenase (BCKD) complex which are affected in patients. We describe here four intronic deletions and an intronic nucleotide substitution in the E2 transacylase gene of type II MSUD, in which the E2 subunit of the BCKD complex is deficient. These new E2 mutations comprise an internal 3.2-kb deletion in intron 4 (causing a 17-bp insertion in mRNA), an internal 12-bp (ttaccttgttac) deletion in intron 4 (creating a 10-bp insertion), a 10-bp (catttctaG) deletion in intron 10/exon 11 junction (leading to a 21-bp deletion), a 2-bp deletion in the exon 5/intron 5 junction (ATgt→A-t) (resulting in the skipping of exon 5), and a G to A transition at nucleotide -7 of intron 9 (causing a 6-bp insertion). These intronic mutations were initially detected by secondary alterations in the mutant E2 mRNA, as a result of aberrant splicing. The 3.2-kb deletion in intron 4 was determined by the amplification of the entire intron from both a normal subject (11.2 kb) and a homozygous patient (8 kb) by long PCR, followed by subcloning and sequencing of regions flanking the deletion. Similar methods were used to identify and characterize the other intronic alterations. Our results depict heretofore undescribed splicing errors caused by the deletion of internal intronic segments, and provide an approach for detecting this class of novel and rare human mutation. The association of the thiamine-responsive phenotype with a subset of the type II MSUD patients studied is also discussed.",
keywords = "Branched-chain α-ketoacid dehydrogenase complex, Cryptic splice site activation, Exon skipping, New splice site creation, Secondary insertions/deletions",
author = "Chuang, {Jacinta L.} and Cox, {Body P.} and Chuang, {David T.}",
year = "1997",
month = "8",
day = "1",
language = "English (US)",
volume = "100",
pages = "736--744",
journal = "Journal of Clinical Investigation",
issn = "0021-9738",
publisher = "The American Society for Clinical Investigation",
number = "3",

}

TY - JOUR

T1 - E2 transacylase-deficient (type II) maple syrup urine disease

T2 - Aberrant splicing of E2 mRNA caused by internal intronic deletions and association with thiamine-responsive phenotype

AU - Chuang, Jacinta L.

AU - Cox, Body P.

AU - Chuang, David T.

PY - 1997/8/1

Y1 - 1997/8/1

N2 - Maple syrup urine disease (MSUD) or branched-chain α-keto-aciduria is an autosomally inherited disorder in the catabolism of branched-chain amino acids leucine, isoleucine, and valine. The disease is characterized by severe ketoacidosis, mental retardation, and neurological impairments. MSUD can be classified into genetic subtypes according to the genes of the branched- chain α-ketoacid dehydrogenase (BCKD) complex which are affected in patients. We describe here four intronic deletions and an intronic nucleotide substitution in the E2 transacylase gene of type II MSUD, in which the E2 subunit of the BCKD complex is deficient. These new E2 mutations comprise an internal 3.2-kb deletion in intron 4 (causing a 17-bp insertion in mRNA), an internal 12-bp (ttaccttgttac) deletion in intron 4 (creating a 10-bp insertion), a 10-bp (catttctaG) deletion in intron 10/exon 11 junction (leading to a 21-bp deletion), a 2-bp deletion in the exon 5/intron 5 junction (ATgt→A-t) (resulting in the skipping of exon 5), and a G to A transition at nucleotide -7 of intron 9 (causing a 6-bp insertion). These intronic mutations were initially detected by secondary alterations in the mutant E2 mRNA, as a result of aberrant splicing. The 3.2-kb deletion in intron 4 was determined by the amplification of the entire intron from both a normal subject (11.2 kb) and a homozygous patient (8 kb) by long PCR, followed by subcloning and sequencing of regions flanking the deletion. Similar methods were used to identify and characterize the other intronic alterations. Our results depict heretofore undescribed splicing errors caused by the deletion of internal intronic segments, and provide an approach for detecting this class of novel and rare human mutation. The association of the thiamine-responsive phenotype with a subset of the type II MSUD patients studied is also discussed.

AB - Maple syrup urine disease (MSUD) or branched-chain α-keto-aciduria is an autosomally inherited disorder in the catabolism of branched-chain amino acids leucine, isoleucine, and valine. The disease is characterized by severe ketoacidosis, mental retardation, and neurological impairments. MSUD can be classified into genetic subtypes according to the genes of the branched- chain α-ketoacid dehydrogenase (BCKD) complex which are affected in patients. We describe here four intronic deletions and an intronic nucleotide substitution in the E2 transacylase gene of type II MSUD, in which the E2 subunit of the BCKD complex is deficient. These new E2 mutations comprise an internal 3.2-kb deletion in intron 4 (causing a 17-bp insertion in mRNA), an internal 12-bp (ttaccttgttac) deletion in intron 4 (creating a 10-bp insertion), a 10-bp (catttctaG) deletion in intron 10/exon 11 junction (leading to a 21-bp deletion), a 2-bp deletion in the exon 5/intron 5 junction (ATgt→A-t) (resulting in the skipping of exon 5), and a G to A transition at nucleotide -7 of intron 9 (causing a 6-bp insertion). These intronic mutations were initially detected by secondary alterations in the mutant E2 mRNA, as a result of aberrant splicing. The 3.2-kb deletion in intron 4 was determined by the amplification of the entire intron from both a normal subject (11.2 kb) and a homozygous patient (8 kb) by long PCR, followed by subcloning and sequencing of regions flanking the deletion. Similar methods were used to identify and characterize the other intronic alterations. Our results depict heretofore undescribed splicing errors caused by the deletion of internal intronic segments, and provide an approach for detecting this class of novel and rare human mutation. The association of the thiamine-responsive phenotype with a subset of the type II MSUD patients studied is also discussed.

KW - Branched-chain α-ketoacid dehydrogenase complex

KW - Cryptic splice site activation

KW - Exon skipping

KW - New splice site creation

KW - Secondary insertions/deletions

UR - http://www.scopus.com/inward/record.url?scp=0030791608&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0030791608&partnerID=8YFLogxK

M3 - Article

C2 - 9239422

AN - SCOPUS:0030791608

VL - 100

SP - 736

EP - 744

JO - Journal of Clinical Investigation

JF - Journal of Clinical Investigation

SN - 0021-9738

IS - 3

ER -