Barth Syndrome

Barth syndrome is an X-linked disorder characterized by cardiomyopathy, neutropenia, skeletal myopathy, growth delay, and increased urinary excretion of 3-methylglutaconic acid. The disorder is caused by mutations in the TAZ gene at Xq28 that result in cardiolipin deficiency and abnormal mitochondria. Cardiac involvement is the most common feature of this syndrome, which usually includes dilated cardiomyopathy or left ventricular noncompaction, and less commonly includes endocardial fibroelastosis or hypertrophic cardiomyopathy. X-linked infantile cardiomyopathies with mutations in the TAZ gene but without Barth syndrome-related symptoms, such as neutropenia and skeletal myopathy, have been reported and postulated to be allelic variants of Barth syndrome. Heart failure is a leading cause of death in such patients, with the highest incidence during the first 6 months of life. In contrast, many patients appear to respond to conventional medical therapy, and cardiac function usually normalizes after 3 years of age. Although Barth syndrome is associated with an increased risk of ventricular arrhythmia, the prognosis of most patients is good after 5 years of age when cardiac function subsequently recovers during infancy. Therefore, early diagnosis and management, with recognition of a wide range of phenotypes, are important for improving the prognosis of Barth syndrome.