gene therapy

Medical Doctor Performing DNA Analysis and Sequencing – Illustration

Duchenne muscular dystrophy (DMD) is an inherited genetic disorder typically afflicting boys.  DMD is a severe type of muscular dystrophy, that causes progressive irreversible muscular weakness over the entire body.  There are treatments that help minimally control symptoms of this neuromuscular disorder, but this horrible disease that affects 1 in 5,000 boys, currently can’t be cured. Researchers from Genethon, the AFM-Telethon laboratory, Inserm (UMR 1089, Nantes) and the University of London (Royal Holloway) have worked for many years to find an effective gene therapy treatment for DMD.

The team of researchers led by Dr. Dickson, designed a gene therapy drug combining an “adeno-associated virus” type viral vector with a shortened version of the dystrophin gene, allowing the production of a functional protein called a microdystrophin.  On a side note, the dystrophin gene is the largest known human gene, and it makes a protein called dystrophin, which is necessary for muscles used in movement to function properly.  Hence when the dystrophin gene is mutated in one of many ways, it fails to make enough dystrophin which causes neuromuscular disorders.

As it sadly turns out Golden Retrievers are prone to Duchenne muscular dystrophy because they have the same potential gene abnormality and are of a similar weight as young boys.  The team of researchers tested their microdystrophin treatment intravenously in 12 Goldens naturally affected by Duchenne muscular dystrophy, with no immunosuppressive treatment given beforehand.  The infusion by nature flowed through the entire body of the dogs and the dystrophin levels returned to a normal level.  As was hoped this lead to the restoration of near normal muscle function observed for over 2 years for the treated dogs following infusion of the microdystrophin, and with no observed side-effects.

Caroline Le Guiner, the main author of this study published in Nature Communications said the treatment exceeded expectations and commented that the approach should work regardless of the particular form of dystrophin mutation.  She went on to say: “This preclinical study demonstrates the safety and efficacy of microdystrophin, and makes it possible to consider developing a clinical trial in patients. Indeed, this is the first time that it has been possible to treat the whole body of a large-sized animal with this protein. Moreover, this innovative approach allows treatment of all patients with Duchenne muscular dystrophy, regardless of the genetic mutation responsible.”