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 duplication mutation?
A duplication occurs when more than one letter is duplicated in the DNA code. The dystrophin gene is the biggest in human cells – the DNA code is more than 10,000 letters long and duplications can range in size from just a few letters to many thousands of letters.
Duplications cause approximately 10% of cases of Duchenne.
DNA code is always read in triplets – or groups of 3 letters. If the number of letters duplicated cannot be divided by 3, then the mutation 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 duplicate 5 letters (for example from the A in cat to O in dog) a cell can no longer read the information.
THE CAT AND ATA NDD OGR ANA NDR AN
In Duchenne, duplications are often so big that they are described by exon number (for example you might hear “exon 2 duplication”). An exon is part of a gene which must be pieced together by a cell to produce a protein.
The dystrophin gene has 79 exons and any combination of exons could be dupicated. This means there are many different duplication mutations.
Which treatments might help?
Everybody living with Duchenne will be offered corticosteroid treatment
There are no treatments in the clinic that specifically target Duchenne caused by duplications. However, at least one company is developing an exon skipping approach that targets duplications. Clinical trials of several potential therapies that are taking place and you can find out more about approaches to treating Duchenne caused by duplications on our information pages about:
- Steroid replacements
- Gene therapy
- Exon skipping
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.
