Barth syndrome is a rare X-linked genetic disorder mostly affecting the males. This is a complex multisystem disease presented with a weak heart at the birth of the infant or usually develops within the first few months of their life. The males with this syndrome have a reduced life expectancy. In most cases, death occurs as the result of heart failure and infection in the infancy or early childhood, however, those who survive into adulthood continue into their late forties. It is estimated that there are less than 10 individuals identified with this syndrome annually in the United States suggesting a prevalence of 1 in every 300,000 to 400,000 births.
Symptoms
Barth syndrome is a multi-system disorder characterized by a weak heart muscle (cardiomyopathy) usually presented at birth, reduced quantity of neutropenia which is the white blood cell essential for fighting off infections, muscle weakness (skeletal myopathy) and growth delay of children who are often below average height and weight gain. The other clinical problems include congestive heart failure, a risk of sudden death (arrhythmia), bacterial infections, lacking stamina, gross motor and fine motor delays. The additional features include diarrhea, osteoporosis, feeding difficulties, mild learning problems, recurrent mouth ulcers, hypoglycemia (low blood sugar) and mild facial appearances such as prominent ears and deep-set eyes. The excessive presence of a substance known as 3-methylglutaconic acid in the urine and blood is also evident. The symptoms vary greatly among the affected individuals with some exhibiting few symptoms while others may feature all symptoms associated with this condition.
Causes
Barth syndrome is caused by the mutation in the gene TAZ (tafazzin) on the X chromosome. It affects the males who carry a single X-chromosome containing the defective gene. Females who carry two X-chromosomes are usually the carrier of this syndrome with a normal TAZ gene that is dominant to the recessive tafazzin gene. This condition is inherited in an X-linked recessive genetic condition where it is transferred from the mother to the son. A mother who passes the defective TAZ gene to her son has a 50% chance of having this syndrome and the daughters will have the 50% chance of being the carrier.
Diagnosis
The diagnosis should be considered for individuals who exhibit features representing this condition. Early diagnosis can be beneficial in providing effective treatment for these affected individuals. In the past, most cases of this syndrome die by three years of age as the result of infection or heart failure, but improved diagnosis and treatment can extend the life of these individuals. The other tests considered for the evaluation can include quantitative urine organic acid analysis, echocardiogram and a complete blood count. A genetic test to identify the mutation responsible for this syndrome can help confirm the diagnosis.
Treatment
There are no specific treatment options available for barth syndrome. The treatment is usually based on the management of the symptoms that develop, as not all signs and symptoms are exhibited at any one time. These individuals require to be carefully monitored for complications such as heart conditions, infections and nutritional difficulties.
References
http://www.uhbristol.nhs.uk/barthsyndromeservice
https://www.barthsyndrome.org/living-with-barth-syndrome/fact-sheets
https://ghr.nlm.nih.gov/condition/barth-syndrome#definition
