Barth syndrome is a rare congenital metabolic and neuromuscular disorder that affects boys. It is passed from mother to son through the sex-linked, or X, chromosome. Symptoms affect multiple systems of the body and may include changes to metabolism, motor delays, hypotonia (reduced muscle tone), delayed growth, cardiomyopathy (leading to a poorly functioning heart), weakened immune system, chronic fatigue, lack of stamina, hypoglycemia (low blood sugar), mouth ulcers, diarrhea, and varying degrees of physical and learning disability. Boys with the disorder also have fewer white blood cells (a condition called neutropenia), which may lead to an increased risk for serious bacterial infections. Barth syndrome affects at least 50 families worldwide, but there is evidence that it is underdiagnosed. On average 50 percent of children born to a carrier mother will inherit the defective gene, but only boys will have symptoms. All daughters born to an affected male will be carriers.

There is no specific treatment for Barth syndrome. Bacterial infections caused by neutropenia can be effectively treated with antibiotics. The drug granulocyte colony stimulating factor, or GCSF, can stimulate white cell production by the bone marrow and help combat infection. Medicines may be prescribed to control heart problems. The dietary supplement carnitine has aided some Barth children but in others it has caused increasing muscle weakness and even precipitated heart failure. Only careful dietary monitoring directed by a physician or nutritionist familiar with the disorder can ensure proper caloric and nutritional intake.

Early and accurate diagnosis is key to prolonged survival for boys born with Barth syndrome. Severe infections and cardiac failure are common causes of death in affected children.

Prepared by the National Institutes of Health