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.