Differing clinical courses and outcomes in two siblings with Barth syndrome and left ventricular noncompaction

Barth syndrome is an X-linked disorder usually diagnosed in infancy. It is characterized by hypotonia, dilated cardiomyopathy, neutropenia, growth retardation, and 3-methylglutaconic aciduria. The syndrome is typically caused by mutations in the TAZ (G4.5) gene, which encodes a novel protein family called the tafazzins. We report the case of two brothers with Barth syndrome and left ventricular noncompaction (LVNC) caused by a splice donor mutation in TAZ. Both had impaired sucking ability at the age of 2 months. The elder brother was diagnosed with LVNC at the age of 4 months; by that time he had developed severe heart failure with metabolic decompensation. He died at 12 months of age due to intractable heart failure despite pharmacological therapy with diuretics, an angiotensin-converting enzyme inhibitor, and a beta-blocker. However, the younger brother, who was diagnosed as having Barth syndrome and LVNC with heart failure at the age of 2 months, received early medical treatment and demonstrated normal echocardiographic findings. Conclusion: The clinical courses of Barth syndrome observed in our cases show the phonotypic variability of this syndrome and suggest that early therapy may be beneficial for maintaining cardiac function.