Duchenne muscular dystrophy (DMD) is the most familiar of the inherited muscle diseases called muscular dystrophies. DMD is life limiting, but advances in care are enabling children born with this disease to survive well into adulthood. The disease is named after the French neurologist Guillaume Duchenne.
The foundation of long survival in DMD is close supervision of breathing and heart functions. DMD however affects much more than these vital functions, and it remains a challenging disease for families and management teams. Thankfully researchers are not resting on their laurels, working ever hard on heart-warming advances. Here are three.
Steroids are now well-established in the treatment of Duchenne muscular dystrophy. What is new however is a better understanding of their benefits in DMD, together with clearer guidance on their use. This is contained in the recent practice guideline update summary: Corticosteroid treatment of Duchenne muscular dystrophy.
Published in the journal Neurology, this document shows how steroids help to improve muscle strength, maintain breathing functions, stabilise ambulation, prevent spinal deterioration (scoliosis), and delay onset of heart disease.
Is there more one could hope for? Yes, a lot more when it comes to genetic diseases.
Idebenone is not new to neurologists. Researchers at Newcastle have been investigating its vision-preserving effect in the mitochondrial disease called Leber’s hereditary optic neuropathy (LHON). Idebenone is thought to improve the activity of mitochondria, the energy-producing component of all cells. Idebenone has also been investigated in other neurological disorders such as Friedreich’s ataxia.
Perhaps as an indication of its growing importance, researchers have now looked at the effect of Idebenone in people with DMD, and they did this in two separate trials. DELPHI is published in the journal Neuromuscular Disorders as Idebenone as a novel, therapeutic approach for Duchenne muscular dystrophy. The authors reported benefit in both cardiac and respiratory function.
DELOS, the second trial, is published in Lancet Neurology and titled Efficacy of idebenone on respiratory function in patients with Duchenne muscular dystrophy not using glucocorticoids. The authors again reported similar benefits. For a synthesised take, see this useful review in Touch Neurology.
But is this enough for ambitious researchers? Of course not…not when you see the promise of gene editing.
I first came across this in Eureka Alert which proclaimed: Gene-editing technique successfully stops progression of Duchenne muscular dystrophy. The gene editing, or gene splicing, technique is called CRISPR. The research itself is published in the journal Science as In vivo genome editing improves muscle function in a mouse model of Duchenne muscular dystrophy.
The researchers used CRISPR technology to delete exon 23 from the Duchenne gene on the X chromosome. Exon 23 is the site of the fault that makes DMD patients unable to produce the muscle protein called dystrophin. By splicing this exon out, the researchers demonstrated an increase in the production of dystrophin. And this increase was significant enough to lead to an improvement in muscle strength.
OK, its only the humble mouse at the moment, but exon skipping therapy is clearly beckoning.