Methylglutaconic Aciduria Type II (Barth Syndrome)

What else is it called?

  • Barth syndrome
  • 3-methylglutaconic aciduria type 2
  • 3 methylglutaconic aciduria, type II
  • BTHS
  • cardioskeletal myopathy with neutropenia and abnormal mitochondria
  • DNAJC19 defect
  • MGA type 2
  • MGA type II
  • TAZ defect

Get in touch

Contact our caring team on 08452 412 173 for help and support. Our phone lines open 10am-4pm, Monday to Friday.

Prefer to email? Our email address is contact@metabolicsupportuk.org.

What causes it?

Barth syndrome is a rare autosomal recessive condition that is caused by mutations in the TAZ gene and can affect multiple body systems. The TAZ gene provides instructions for making a protein called tafazzin. Tafazzin is located in structures called mitochondria, which are the energy-producing centers of cells, it is involved in providing the mitochondria with its shape, structure and assisting with protein transfer. This protein is also involved in altering a fat called cardiolipin which is believed to play an important role in the inner mitochondrial membrane.

A mutation to the TAZ gene Is likely to mean that the tafazzin protein has little or no functionality and cannot alter the cardiolipin protein. Therefore, tissues in the body which require high energy demands from the mitochondria such as the heart and muscles may be susceptible to death due to a lack of energy from this disorder.

How common is it?

Barth syndrome is estimated to affect 1 in 300,000 to 400,000 individuals worldwide. More than 150 cases have been described in the scientific literature to date, this condition features almost exclusively in males, although it can feature in females.

What are the signs and symptoms?

The severity of signs and symptoms among affected individuals is also highly variable

  • Cardiomyopathy [Weakened heart]
  • Hypertonia
  • Neutropenic due to small number of white blood cells
  • Generally short in stature
  • Vomiting

It is common especially for males with Barth syndrome can cycle between a small number of white blood cells to a medium number of white blood cells. Males often have distinctive facial characteristics with Barth syndrome such as prominent cheeks which is most evident in infancy. Boys with this condition are generally smaller than average and will appear small on percentile charts when compared to others their age, however it is not uncommon for them to go through a growth spurt when reaching puberty and catch up to the expected levels of growth.

Affected individuals typically have normal intelligence but often have difficulty performing tasks involving math or visual-spatial skills such as puzzles.

Sadly, males with this condition have a shorter life expectancy, many pass away from heart failure or from infection from a lack of white blood cells in late childhood or early adulthood.

 

How is it diagnosed?

Males with Barth syndrome have increased levels of a substance called 3-methylglutaconic acid in their blood and urine. Therefore, this condition may be checked by blood sample analysis or via a 24-hour urine collection or a one-off random urine sample analysis.

If this condition is present within your family history, it is likely that your baby will be tested for this condition with the new born screening test.

If your baby’s new born screening result for Barth syndrome is out of the normal range, your doctor or the screening programme lead will contact you for your baby to have additional testing.

Can it be treated?

Currently there is no treatment for Barth syndrome, treatment is usually aimed at managing symptoms as they present. There are trials that are ongoing currently looking at gene replacement therapy for the TAZ gene in United states, Florida however more time and research is still needed to assert if this method is successful as a treatment option. The full details of the article for this are set to be available from February 2020.

Gene therapy is an experimental technique that uses genes to treat or prevent disease. In the future, this technique may allow doctors to treat a disorder by inserting a gene into a patient’s cells instead of using drugs or surgery.

Do my family need to be tested?

Human X and Y chromosomes determine the biological sex of a person, with XX specifying female and XY specifying male

X-linked inheritance patterns differ depending on the type of inheritance. Recessive X linked conditions are always passed through the maternal line with the condition appearing in males and being carried in females, but not usually expressed. Whereas with dominant, one mutated copy of the gene in each cell is sufficient for a person to be affected by an autosomal dominant disorder

Males have a greater chance of receiving an X-linked inheritance due to the masking effect of the x gene, if you have two of these x genes as females do then the other X linked gene can mask the effects of the mutated one, whereas with males you only inherited one of these genes so there would be no masking effect.

Relevant Organisations

References

References are available on request. Please contact Helen Morris by phoning 0845 241 2173 or emailing helen@metabolicsupportuk.org [Resource Library No: AAP002].

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