Barth Syndrome

What is Barth syndrome?

Barth syndrome is a rare, metabolic, and neuromuscular disorder that occurs exclusively in males, since it is passed from mother to son through the X chromosome.  The main characteristics of the condition include abnormalities of heart and skeletal muscle; low levels of certain white blood that help to fight bacterial infections; and growth retardation.  

What are the symptoms of Barth syndrome?

• Weakened heart muscle (cardiomyopathy) that leads to the enlargement of the heart’s lower chambers (ventricles) 
• Weakening of the heart’s pumping action, reducing the volume of blood circulating to the lungs and the rest of the body (heart failure) 
• Abnormally diminished muscle tone (hypotonia) 
• Muscle weakness (skeletal myopathy) 
• Delayed development of gross motor skills (crawling, walking, running, jumping, and maintaining balance) 
•  Weakness of the facial  
• Mild learning disabilities  
• Proclivity to recurrent bacterial infections due to low levels of circulating neutrophils in the blood (neutropenia) 
• Abnormally increased levels of a substance called 3-methylglutaconic acid in the urine and blood.

What causes Barth syndrome?

Barth syndrome is caused by mutations in the TAZ gene, which is located on the X chromosome.  The TAZ gene provides “instructions” for a group of proteins called tafazzins that serve at least two functions. First, these proteins play a role in the maintenance of the inner membranes of structures inside cells called mitochondria. Cells depend on mitochondria to produce the energy they need. Tafazzins also promote the development of bone cells.   Mutations in the TAZ gene that cause Barth syndrome disrupt the protein’s ability to function correctly, thereby causing the signs and symptoms of Barth syndrome.  

How is Barth syndrome diagnosed?

Barth syndrome may be diagnosed based upon a thorough clinical evaluation, identification of characteristic physical findings, a complete patient and family history, and a variety of specialized tests.   These tests include: 

• Metabolic screening tests 
• Genetic tests  

Experts indicate that a diagnosis of Barth syndrome should be considered for any male infant or child with dilated cardiomyopathy of unknown cause (idiopathic); low levels of circulating neutrophils (neutropenia); elevated urinary levels of 3-methylglutaconic acid (aciduria); abnormal mitochondria within heart muscle; and/or muscle abnormalities (myopathy) of unknown cause that occur in association with growth retardation.  

What are the treatments for Barth syndrome?

Treatment for Barth syndrome is generally directed toward the specific symptoms.  Many infants and children with Barth syndrome require therapy with diuretic and digitalis medications to treat heart failure. Some affected children are gradually removed from such cardiac therapy during later childhood due to improvement of heart functioning.  

Where can I find out more about Barth syndrome?

• National Organization for Rare Disorders (NORD) 
• Barth Syndrome Foundation  
• NIH