Barth Syndrome, An Overview
Barth syndrome is a rare congenital metabolic and neuromuscular disorder. It only affects boys. The "Barth" gene (called G4.5 or TAZ1) was discovered in 1996. It is passed from mother to son through the sex-linked, or X, chromosome.
Barth syndrome is also know as 3-Methylglutaconic aciduria type II and Cardiomyopathy-neutropenia syndrome. The syndrome was named after Dr. Peter Barth for his research and discovery in 1983.
Four major criterion are used for diagnosis: cardioskeletal myopathy (poorly functioning heart), neutropenia (decreased white blood cells which make them susceptible to infections), growth retardation, and 3-methylglutaconic aciduria (metabolism distortions). The level of 3-methylglutaconic acid is increased at any age in Barth Syndrome patients, but especially high (up to 200X normal) between the ages of six months and three years. The level of 3-methylglutaconic acid appears to be largely independent of the severity of other features of the disorder.
Other symptoms that parents might notice include hypotonia (reduced muscle tone), delayed growth, chronic fatigue, mouth ulcers, varying degrees of physical and learning disability.
Barth syndrome affects at least 50 families worldwide. The syndrome is believed to be severely under-diagnosed and may be estimated to occur in 1 out of approximately 200,000 births.
Because it is carried by the X-chromosome, 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.
Historically, patients with Barth Syndrome died of heart failure or infection by 3 years of age. This is changing with improved diagnosis and appropriate medical treatment.
Barth Syndrome Foundation
National Institute of Neurologic Disorders and Stroke
John Hopkins Medicine – Barth Syndrome