GM00649

GM00649 Fibroblast

Description:

MAPLE SYRUP URINE DISEASE (MSUD), TYPE IA
BRANCHED-CHAIN KETO ACID DEHYDROGENASE E1, ALPHA POLYPEPTIDE; BCKDHA

Affected:

Yes

Sex:

Male

Age:

9 MO (At Sampling)

Overview

Repository

NIGMS Human Genetic Cell Repository

Subcollection

Heritable Diseases

Class

Disorders of Amino Acid Metabolism

Cell Type

Fibroblast

Transformant

Untransformed

Race

White

Family Member

Relation to Proband

proband

Confirmation

Molecular characterization after cell line submission to CCR

Species

Homo sapiens

Common Name

Human

Remarks

Elevated urine leu, ileu, and val; delayed psychomotor develop; abnormal EEG; deficient BCKD (BCKAD) complex activity; posititve for cross-reactive material for BCKD (BCKAD) complex subunits E1A, E2, and E3; E1A (BCKDE1A or BCKDHA) gene shows 8-bp deletion in exon 7/Y438N (formerly designated Y393N) mutations

Characterizations

Passage Frozen

IDENTIFICATION OF SPECIES OF ORIGIN

Species of Origin Confirmed by Nucleoside Phosphorylase, Glucose-6-Phosphate Dehydrogenase, and Lactate Dehydrogenase Isoenzyme Electrophoresis

MITOCHONDRIAL DNA ANALYSIS

Eisenstein et al (Am J Hum Genet 37:A8 1985) employed a rabbit anti-bovine kidney BCKDH antibody to show that mitochondrial extracts from this culture in a western blot analysis were positive for crossreactive material for BCKDH subunits E1A (branched-chain alpha-keto acid decarboxylase) E2 (dihydrolipoyl transacylase) and E3 (dihydrolipoyl dehydrogenase).

3-methyl-2-oxobutanoate dehydrogenase

According to the submitter, biochemical test results for this subject showed decreased enzyme activity. EC Number: 1.2.4.4

Gene

BCKDHA

Chromosomal Location

19q13.1-q13.2

Allelic Variant 1

608348.0002; MAPLE SYRUP URINE DISEASE, CLASSIC TYPE IA, DUE TO DEFICIENCY OF E1A

Identified Mutation

8-BP DEL, NT887-894, FS255TER; In the compound heterozygote with the tyr393-to-asn mutation (248600.0001) reported by Zhang et al. [J Clin Invest 83: 1425 (1989)], Chuang et al. [Am. J. Hum. Genet. 55: 297 (1994)] demonstrated that the other allele carried an 8-bp deletion involving bases 887 through 894. The deletion resulted in a nonsense codon 255 of the mature E1-alpha subunit. The deletion abolished an SmaI restriction site in exon 7. This alteration in restriction was used to study segregation of the deletion in the family. The mother was found to be heterozygous. (When the tyr393-to-asn mutation was reported in 1989, the second allele was postulated to be a regulatory mutation, on the basis of a reduced mRNA level for this allele. Studies of the promoter regulatory region of the gene from this patient (GM00649) revealed that the patient and the mother were heterozygous for an A-to-T transversion at base -284. Using the luciferase reporter assay, however, Chuang et al. [Am. J. Hum. Genet. 55: 297 (1994)] found that the A-to-T transversion was associated with normal activity, indicating that it represents a normal polymorphism.)

Gene

BCKDHA

Chromosomal Location

19q13.1-q13.2

Allelic Variant 2

Y438N; MAPLE SYRUP URINE DISEASE, CLASSIC TYPE IA, DUE TO DEFICIENCY OF E1A

Identified Mutation

TYR438ASN (FORMERLY TYR393ASN)

Phenotypic Data

Remarks

Publications

Chuang JL, Davie JR, Chinsky JM, Wynn RM, Cox RP, Chuang DT, Molecular and biochemical basis of intermediate maple syrup urine disease. Occurrence of homozygous G245R and F364C mutations at the E1 alpha locus of Hispanic-Mexican patients. J Clin Invest95:954-63 1995

PubMed ID: 7883996

Chuang JL, Fisher CR, Cox RP, Chuang DT, Molecular basis of maple syrup urine disease: novel mutations at the E1 alpha locus that impair E1(alpha 2 beta 2) assembly or decrease steady- state E1 alpha mRNA levels of branched-chain alpha-keto acid dehydrogenase complex. Am J Hum Genet55:297-304 1994

PubMed ID: 8037208

Eisenstein, Characterization of branch chain keto acid dehydrogenase (BCKAD) deficiency in maple syrup urine disease (MSUD). Am J Hum Genet37:A8 (1985):297-304 1985

PubMed ID: 8037208

Chuang DT, Ku LS, Kerr DS, Cox RP, Detection of heterozygotes in maple-syrup-urine disease: measurements of branched-chain alpha-ketoacid dehydrogenase and its components in cell cultures. Am J Hum Genet34:416-24 1982

PubMed ID: 7081220

Fensom AH, Benson PF, Baker JE, A rapid method for assay of branched-chain keto acid decarboxylation in cultured cells and its application to prenatal diagnosis of maple syrup urine disease. Clin Chim Acta87:169-74 1978

PubMed ID: 668138