New drug offers hope to muscular dystrophy and cystic fibrosis sufferers

Apr 23 2007

Scientists in the United States say an experimental drug may be able to compensate for the genetic error responsible for some cases of Duchenne Muscular Dystrophy (DMD) and cystic fibrosis.

The scientists from PTC Therapeutics, in New Jersey, and the Universities of Pennsylvania and Massachusetts have tested the drug PTC124 on mice and say it promises to restore the muscle function normally lost in DMD.

PTC124 works by allowing cells to read through certain mistakes in the genetic code for the protein dystrophin which missing in 15% of patients with DMD.

Although trials have already begun in 100 humans, the results could take years, but the researchers have catalogued more than 1,800 genetic disorders caused by nonsense mutations that could be treated by the drug.

Muscular dystrophy is a group of genetic disorders that cause the muscles in the body to gradually weaken over time and mobility to be lost; it shortens the victims life span and there is currently no cure; treatments are available that alleviate symptoms, such as muscle spasm, and enable people with MD to lead a good quality of life.

DMD is the commonest and most severe form and affects one in every 3,500 boys; it too is characterised by weakness and muscle wasting.

Children born with cystic fibrosis suffer digestion and respiratory problems and also tend to die early.

Both conditions are caused by so-called "nonsense mutations" in the child's DNA that means the sufferer lacks a vital protein.

The drug PTC124 appears to have the potential to become a treatment in the longer term for some people with DMD as the mice trials found it adhered and helped override the mutation in the dystrophin gene that tells it to halt production of the protein; instead of stopping, the full-length dystrophin protein was made.

PTC124 binds to a cell component called the ribosome, which reads genetic the code and translates it so proteins can be made.

However PTC124 did not prevent the ribosome from reading correct "stop" signals in genetic codes for other proteins.

Lead researcher Dr. H Lee Sweeney says the new class of treatment has the potential to help a large number of patients with different genetic diseases that have the same type of mutation.

Other experts have welcomed the results and scientists continue to strive to find a way of reversing or preventing the muscle damage.