Barth syndrome diagnosed in the subclinical stage of heart failure based on the presence of lipid storage myopathy and isolated noncompaction of the ventricular myocardium.

Barth syndrome (BTHS) is an X-linked disorder characterized by skeletal myopathy, neutropenia, growth delay, and cardiomyopathy. It is caused by mutations in the tafazzin gene (TAZ). Although early diagnosis is critical to prevent the progression of heart failure, this disease remains unrecognized when heart failure is not clinically significant. Here we report on a 13-year-old boy with no family history of BTHS who was diagnosed with the syndrome in the subclinical stage of heart failure. The clues to the diagnosis of BTHS in this patient were the findings of lipid storage myopathy in the skeletal muscle biopsy, elevated plasma brain natriuretic peptide, and the diagnosis of isolated noncompaction of the ventricular myocardium in echocardiography. Genetic studies of TAZ revealed a disease-causing mutation (p.Gly216Arg) in this patient. Physicians should be aware of the possibility of this disease and carry out genetic studies when it is considered.