Splicing mutation in TAZ gene leading to exon skipping and Barth syndrome

Barth syndrome is a monogenic X-linked disorder characterized by cardiomyopathy, skeletal myopathy and neutropenia. It is caused by deficiency of cardiolipin and associated with mutations in the tafazzin gene (TAZ). A 3 years old boy with dilated cardiomyopathy, neutropenia and growth retardation was investigated. Genetic screening found a new variant in the junction of intron 2 and exon 3 of the TAZ gene - c.239-1_239delinsTT. Functional analysis of the variant revealed the aberrant splicing of exon 3 leading to its complete excision from mature mRNA and frameshift at the beginning of tafazzin. Variant c.239-1_239delinsTT can be classified as pathogenic based on splicing alteration and typical clinical phenotype observed in TAZ mutation carriers.