Duchenne muscular dystrophy (DMD) is a rare progressive neuromuscular
disorder caused by an absence of dystrophin that results in generalized muscle
weakness and muscle wasting. DMD is inherited in an X-linked manner and results
in irreversible loss of muscle tissue and early death. Standard treatment includes
corticosteroids and palliative care, which help manage some symptoms without
treating the actual genetic defect. CRISPR-Cas9 genome editing is a rapidly
advancing area of neuromuscular research, with the potential to permanently fix
the underlying genetic cause at the DNA level. In preclinical studies it has been
shown that CRISPR technology can restore dystrophin through the use of methods
such as exon skipping or frame-restoration, and thus decrease tissue degeneration
due to dystrophin deficit. New advances in base and prime editing provide more
precise methods for genetic correction and less likelihood of double-strand breaks
than some previous-generation "cut-and-paste" gene-editing strategies.
Nevertheless, shifting these methods from animal models to human therapies
brings significant challenges. Considerations include the immune response to
adeno-associated virus (AAV) vectors, the potential for off-target effects, and
challenges with delivering the treatment to all muscle groups, most notably the
heart joint and diaphragm. New clinical research, including the EMBARK clinical
trial results, shows how difficult it is for patients to achieve long-lasting benefits.
Despite these challenges, continued improvement in the accuracy of gene editing
presents some hope that DMD will have an opportunity to be transitioned from a
symptom management to a cure for the disease if current safety and delivery
challenges can be overcome.
Keywords: Duchenne muscular dystrophy, CRISPR Cas9 genome editing,
dystrophin restoration
