A novel intronic mutation of the TAZ ( G4.5) gene in a patient with Barth syndrome: creation of a 5' splice donor site with variant GC consensus and elongation of the upstream exon.

Mutation analysis of the TAZ ( G4.5) gene was performed on a patient with Barth syndrome. The reverse transcription/polymerase chain reaction procedure showed aberrant splicing and elongation of exon 3 because of the insertion of 106 bases (IVS3+1 to +106) between exons 3 and 4. The genomic DNA revealed an intronic mutation four bases downstream from the new cleavage site (IVS3+110G-->A). The IVS3+110G-->A mutation created a novel 5' splice site that showed GC but not GT, and the additional splice site was used preferentially over the upstream authentic slice site. This is a new type of splicing mutation responsible for a human genetic disease.