Barth syndrome is a genetic disorder characterized by muscle weakness, including weakness and enlargement of the heart (cardiomyopathy). Other symptoms of Barth syndrome include low muscle tone (hypotonia), delayed growth, and a reduced ability to fight infections (neutropenia). These symptoms may be noticeable at birth or may not appear until later in life.
Barth syndrome is caused by a mutation to the TAZ gene, which is responsible for maintaining a fat called cardiolipin. Cardiolipin works with the part of cells that produce energy (mitochondria). A mutation in TAZ causes Barth syndrome because the cardiolipin no longer supports energy production. Barth syndrome is both a mitochondrial disease and an organic acid disorder because the lower-functioning mitochondria are less effective at breaking down organic acids (such as 3MGA), causing a build-up in the body.
Males are more likely to develop Barth syndrome because TAZ is located on the X chromosome. Males have one X chromosome (one copy of TAZ) while females have two (2 copies of TAZ). Thus for boys, if there is a change in their only copy of TAZ, they will have symptoms. Girls need both of their TAZ gene copies to be changed in order to have symptoms.
Diagnosis may include a urine sample to check for high levels of organic acids. Genetic testing may be used to confirm the diagnosis. Treatment varies depending on symptoms. Research in gene therapy is ongoing with the hope of developing a cure. Many babies are screened for 3MGA disorders at birth so that treatment can begin early, but the conditions included in newborn screening vary from state to state. For more information, visit Baby’s First Test.Talk with your baby’s doctor about the most current treatment options. Genetic counselor and support groups are also a good sources of information.