Saving lives through education, advances in treatment and finding a cure for Barth syndrome
Diagnosing Barth syndrome
Waiting to hear whether your son has this condition is often a really worrying time. You can’t really do anything until you know what you’re dealing with. However, this can be a good time to familiarise yourself with some of the basic information about the condition and how it is diagnosed here in the UK.
Biochemical and Genetic Testing
There are two main ways of testing to see if someone has Barth syndrome. Your son can have a genetic test from a blood sample (which can take a long time) or, thanks to the latest research, he can have a new biochemical "cardiolipin test" which can be performed very reliably on as little as 3ml of blood. This newer cardiolipin test result usually takes only 1-2 weeks.
If the cardiolipin test is positive for Barth syndrome, then traditional genetic testing will be done afterwards, just to be doubly sure. However, once you get back a definitive cardiolipin test, you can usually go ahead and assume that your son does have Barth syndrome.
There is no charge for this testing for UK patients as it is funded by NHS Specialised Services. Please note that there is also no longer a need for an invasive muscle biopsy to diagnose the condition.
How rare is Barth syndrome?
Latest figures suggest that the incidence rate is approximately 1:140 000, which means that 1 in every 140 000 live births will be a baby with Barth syndrome. It affects people from all ethnic groups.
How do you get Barth syndrome? (Inheritance)
This condition is named after Dr Peter Barth who first described it in 1983. He described a disease affecting only boys (X-linked genetic condition) which was inherited through the female line and could therefore affect boys in different generations of a family.
The “Barth” gene (tafazzin gene) lies on structures called chromosomes. Women have two X chromosomes (XX), so they have a back-up copy and should anything go wrong on the Barth gene on one X chromosome, they can simply use their other, healthy copy of the gene from their second X chromosome. Thus women can become carriers of the disease without showing any symptoms.
Men have one X chromosome and one Y chromosome (XY) so they do not have a back-up copy if anything goes wrong on their X chromosome. Men who have an altered gene on their X chromosome thus become affected.
- If a woman carrier has a boy, there is a 50% (1 in 2) risk that the boy will be affected.
- If a woman carrier has a girl, there is a 50% (1 in 2) risk that the girl will be a healthy carrier, like her mother.
- For men with Barth syndrome who have children, all of their daughters will be healthy carriers.
- Men do not pass on their X chromosomes to their sons. Therefore, all the sons of men with Barth syndrome are completely healthy.
- Sometimes boys are born with X-linked conditions even though their mothers are not carriers (spontaneous mutation). When this happens, it is particularly important to get specialist advice about future pregnancies
Carrier Testing and Genetic Counselling
If you (or someone in your family like your mother, grandmother, sister, aunt etc) have a history of multiple male miscarriages or stillbirths, you should be tested to see if you’re a carrier of Barth syndrome. If you have a boy who has been diagnosed with Barth syndrome, you will also be offered testing. Your blood can be analysed to see if you have the same genetic mutation as your son has – if you do, then this means you are a carrier.
You can also discuss options regarding having your other sons and daughters tested if necessary.
Medical emergency or just need to talk?
"We first heard about Barth syndrome back in 2003 and it took us almost 4 years to get a diagnosis for our son (now 14 years old). It’s wonderful to see that research funded by Barth families has led to a new cardiolipin test which can give you the answers you need quickly and reliably…"