Barth syndrome (BTHS) is a rare, genetic disorder of lipid metabolism that primarily affects males. It is caused by a mutation in the tafazzin gene (TAZ, also called G4.5) which leads to decreased production of an enzyme required to produce cardiolipin. Cardiolipin is an essential lipid that is important in energy metabolism.
BTHS is an X-linked genetic condition passed from mother to son through the X chromosome. A mother who is a carrier of BTHS shows no signs or symptoms of the disorder herself. On average, 50 percent of children born to a carrier mother will inherit the defective gene, but only boys will develop symptoms. All daughters born to an affected male will be carriers.
BTHS, which affects multiple body systems, is considered serious. Its main characteristics often include combinations in varying degrees of:
- Cardiomyopathy – a disorder of the heart muscle leading to a poorly functioning heart
- Neutropenia – a reduction in the number of white blood cells which may lead to an increased risk for bacterial infections
- Hypotonia – reduced muscle tone
- Muscle weakness
- Undeveloped skeletal muscles
- Delayed growth
- Lack of stamina
- Varying degrees of physical disability
- Methylglutaconic aciduria – an increase in an organic acid that results in abnormal mitochondria function
Although some with BTHS may have all of these characteristics, others may have only one or two, and, thus, are often misdiagnosed.
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.
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 children with Barth syndrome 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.