What is Barth syndrome?

Barth syndrome (BTHS) is a rare, life-threatening genetic disorder, which primarily affects males. It is caused by a mutation in the tafazzin gene (TAZ, also called G4.5), resulting in an inborn error of phospholipid metabolism, affecting many systems of the body.   

Historically death from heart failure or infection occurred by three years of age, but with improved diagnosis, medical therapy and monitoring, survival has been extended, with many survivors now into their adult years. Survivors of BTHS, however, almost always live with extremely compromised physical health, and those few who enjoy relatively good health live every day with medical conditions that can become life-threatening with little or no warning. Someone with BTHS will likely suffer with varying degrees of BTHS symptoms. 

Cardiac Aspects of Barth Syndrome

Cardiomyopathy (heart muscle weakness) is generally worse in the left side of the heart.  The left side of the heart pumps oxygenated blood to the entire body. The heart muscle wall can be dilated (thin) and/or hypertrophic (thick), in either case the left side of the heart is too weak to push the blood out to the body. As the function of the left side of the heart worsens the right side of the heart has to work harder to push blood from the body into the left side of the heart. This causes the left side of the heart to become larger with the muscle, thinning the muscle wall of the left side of the heart even more. When the right side of the heart fails blood builds up in the body causing swelling in the abdomen and extremities. In basic terms when the heart can’t pump enough blood to meet the body’s needs it is known as heart failure. Heart function can significantly deteriorate very suddenly and unexpectedly.

About half of the people diagnosed with BTHS have left ventricular noncompaction, which is a condition that causes deep trabeculations (crevices), generally at the apex of the heart. Blood will pool in these trabeculations, which leads to the formation of blood clots. Dislodged clots can lead to stroke. Heart muscle cell abnormalities also place the individual with BTHS at an increased risk of having an arrhythmia (abnormal heart rhythm). Arrhythmia can lead to abrupt loss of heart function altogether. This is known as cardiac arrest. Without intervention the individual will face certain death. Life-threatening arrhythmias can occur, even when the heart function is in normal range.

Neutropenia

Neutropenia is a condition where the individual with BTHS has very low and sometimes zero white blood cells called neutrophils. The neutrophils are the most abundant white blood cells in the body. A person who does not have adequate numbers of neutrophils are unable to fight bacterial infections. Neutropenia places the individual with BTHS at an increased risk of acquiring serious infections such as bacterial pneumonia and skin abscesses. This can lead to sepsis. It is not always possible to predict when the person with BTHS is neutropenic. Some people experience neutropenia at regular intervals; this is known as cyclic neutropenia. Some people are always neutropenic; this is known as chronic neutropenia. Some people experience neutropenia with no predictability whatsoever; this is known as intermittent neutropenia. A common cold can be life-threatening for someone with BTHS when they are neutropenic. A rectal temperature should NEVER be taken on the individual with BTHS. Death in BTHS is most commonly due to sepsis from neutropenia and heart failure. 

Low Muscle Mass and Fatigue

All muscles, including the heart, have a cellular deficiency which limits their ability to produce energy. This causes extreme fatigue during any endeavor that requires strength or stamina (e.g., walking, reading, writing, and growing and thinking). Low muscle mass significantly limits the individual’s ability to tolerate periods of fasting. Even during brief periods of time, they are at risk of becoming hypoglycemic. Serious hypoglycemic crisis situations have occurred in BTHS. Any symptoms of low blood sugar (e.g., onset of excessive weakness, change of pallor, excessive sweating) must be taken seriously.

Given their diminished body stores, BTHS individuals often tolerate illnesses poorly, especially those that include diarrhea or vomiting.  

Failure-to-Thrive and Growth Delay

Most individuals with BTHS are below-average in weight and height, often substantially so. Short stature in early years is often followed by an accelerated growth pattern during mid-to-late phase of puberty. Poor growth is often assumed to be evidence of poor nutrition, but this is not the case. Fortunately, the older boys with BTHS have grown to average and above average heights, but their growth takes longer to come to completion than their peers.

Exercise Intolerance

Symptom severity of BTHS is highly variable, even in families where there is more than one person diagnosed with the condition. Amongst those who have BTHS, some have weaker hearts than others, some have weaker immune systems than others, and some have slower physical developmental rates than others. However, almost all individuals with BTHS suffer from muscle weakness and a general fatigue, which significantly limits their ability to perform normal life activities.

It should be noted again that relatively good health in someone with BTHS offers no indication of disease severity in the future. Therefore, educators need to understand that a student with BTHS wakes up every morning and goes to sleep every night with a life-threatening condition. Some students are underweight, frail, easily fatigued, and easily identifiable as “sick,” while others have appeared healthy and strong for years only to suffer sudden illness.

In order to fight their symptoms, individuals with BTHS must be carefully monitored by doctors, so they will likely miss school for doctors’ appointments more often than other students. Many of the students take medications, which treat some symptoms of their condition but might also complicate other areas of their well-being. Furthermore, some students have to experiment with medications before finding successful combinations, and these periods of trial and error can be painful and traumatic for them. 

Ultimately, in addition to focusing on the intellectual development of students with BTHS, educators must always be sensitive to their medical conditions and physical needs.

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