The molecular defect in propionic acidemia: exon skipping caused by an 8-bp deletion from an intron in the PCCB allele.
Propionic acidemia is an autosomal recessive metabolic disease resulting from a deficiency of propionyl CoA carboxylase (PCC) activity. To investigate the genetic basis of propionic acidemia, we isolated a cDNA encoding the precursor of the beta subunit of human PCC (beta PCC). The cloned cDNA sequence was 1,832 bp long and the open reading frame of 1,617 nucleotides encoded a polypeptide of 539 amino acids with a molecular mass of 58,202 Da. The human beta PCC sequence shared a high degree of homology (91%) with the full-length cDNA of rat beta PCC at the amino acid level; there were only 47 differences among 539 amino acid residues compared. Polymerase chain reaction amplification and sequencing of cDNA from a beta subunit-deficient Japanese patient revealed a deletion of 101 nucleotides consisting of one exon from mature mRNA. This deletion resulted in a frameshift and a stop codon in the new frame. Analysis of the genomic DNA revealed a homozygous 8-bp deletion from bp3 to bp10 of the intron just downstream of the deleted exon. This deletion disrupted the consensus 5' splice signal and led to exon skipping.
Ohura
T
T
Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan.
Ogasawara
M
M
Ikeda
H
H
Narisawa
K
K
Tada
K
K
D000483:Alleles; D000592:Amino Acid Metabolism, Inborn Errors / Q000201:enzymology / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D019735:Carbon-Carbon Ligases; D002460:Cell Line; D002478:Cells, Cultured; D002872:Chromosome Deletion; D004247:DNA / Q000032:analysis; D005091:Exons / Q000235:genetics*; D005260:Female; D005347:Fibroblasts / Q000166:cytology; D016368:Frameshift Mutation; D006801:Humans; D007438:Introns / Q000235:genetics*; D008025:Ligases / Q000172:deficiency / Q000235:genetics*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011422:Propionates / Q000097:blood*; D012333:RNA, Messenger / Q000032:analysis; D012867:Skin / Q000166:cytology
D011422:Propionates; D012333:RNA, Messenger; D004247:DNA; D008025:Ligases; D019735:Carbon-Carbon Ligases; C022458:propionyl CoA carboxylase (ATP-hydrolyzing)