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.