People born with McArdle disease are unable to produce an enzyme called muscle phosphorylase. This enzyme is important in producing the fuel source required by the skeletal muscles for exercise.
In the brain, there is an enzyme similar to muscle glycogen phosphorylase called brain glycogen phosphorylase. The brain form of the enzyme has been seen in muscle fibres after they have been damaged, suggesting that it might be possible to ‘switch on’ the brain enzyme in muscle to compensate for the missing muscle glycogen phosphorylase
As part of Dr Quinlivan’s pilot study, people with McArdle disease will receive a drug every day for six months, to stimulate brain glycogen phosphorylase production. Administration of the drug will then be gradually reduced and stopped, gathering evidence as to whether this drug improves symptoms of the condition. The trial will involve exercise testing to see if the treatment is having any effect.