A novel splicing mutation in propionic acidemia associated with a tetranucleotide direct repeat in the PCCB gene.

Propionic acidemia is an inborn error of organic acid metabolism caused by a deficiency of propionyl Coenzyme A (CoA) carboxylase. cDNAs sequenced from a beta subunit deficient Japanese patient (no. 187) showed an in-frame 57-bp deletion in one allele. Genomic DNA analysis revealed a four-nucleotide deletion of bases 3 to 6 in the 3' intron adjacent to the deleted exon, which disrupted the consensus 5' splice signal and caused exon skipping. This deletion removed one-half of a tetranucleotide direct repeat at the splice junction and presumably resulted from slipped mispairing.