Duchenne is a genetic condition. This means the condition is caused by genetic mutations – alterations or changes – in a gene. Duchenne is caused by mutations in a single gene called the dystrophin gene. These mutations prevent cells from producing the dystrophin protein which is needed for muscle function.
What is a point mutation?
A point mutation is a very small alteration in the DNA code, where a single letter is either changed, duplicated or deleted.
Point mutations cause 15-30% of cases of Duchenne.
Genes are the instructions that allow a cell to make a protein and the dystrophin gene is the biggest in human cells – the DNA code is more than 10,000 letters long.
DNA code is always read in triplets – or groups of 3 letters. Deleting or duplicating a single letter prevents a cell reading the message correctly. If you imagine a short sentence of 3 letter words:
THE CAT AND DOG RAN AND RAN
and delete a single letter (for example the A in cat)
Although most of the information is still present, because cells always read DNA in groups of 3 letters, the cell can no longer read the information. The same thing happens if a letter is duplicated (a second A in CAT):
More rarely, a single letter might be changed. This does not affect how a cell reads the code but changes the meaning of the message. Here, a single letter changes (the C in cat to an R):
This changes the message and when a genetic instruction changes this can stop a protein working correctly.
Nonsense mutations
Nonsense mutations are a special type of point mutation that cause a slightly different problem inside cells. There’s a separate page where you can find out more about nonsense mutations and treatments.
Which treatments might help?
There are currently no treatments in the clinic or being tested in clinical trials that specifically target point mutations.
However, everybody living with Duchenne will be offered corticosteroid treatment and potential treatments designed to work regardless of mutation type are being tested in clinical trials.
You can find out more about approaches to treating Duchenne caused by point mutations on our information pages about:
- Steroid replacements
- Gene therapy
Got a question?
If you’ve got a question, we’re happy to help. You can get in touch by emailing Neil (our Head of Research) or call us on 02072508240.
