A case of myositis following gene therapy for DMD

American clinicians involved in gene therapy designed to deliver a truncated version of the dystrophin gene (microdystrophin) by vein, using an adeno-associated virusCe sont les plus petits micro-organismes vivants. Pour vivre et se multiplier, ils parasitent des cellules dont ils détournent à leur profit la machinerie., have reported a complication that was already known but rarely encountered:

• the patient was 9 years old and still able to walk at the time of gene therapy (GT),
• his genotype corresponded to a large deletion (exons 3 to 43),
• he was taking part in the phase 3 ENDEAVOR trial promoted by the Sarepta laboratory,
• one month after injection, a limb-girdle muscle deficit and bulbar problems appeared,
• serum CPKEnzyme contenue dans les cellules musculaires, qui est libérée dans le sang en cas d’atteinte musculaire. levels rose to 28,000 IU/l and histology was clearly in favour of myositis,
• prolonged immunosuppressive treatment enabled the patient to return to a pre-TG state.

This is the first published case for which exhaustive data are available (of the six reported by the various laboratories). The predominance of bulbar disorders as the mode of presentation is also noteworthy.

Immune-mediated myositis following gene therapy for Duchenne muscular dystrophy: a case report. Iannaccone ST, Cai C, Rhem B et al. J Neurol. 2024 Jun 22.