A landmark CRISPR gene editing study has been conducted on dogs with Duchenne Muscular Dystrophy by researchers at UT Southwestern’s Hamon Center for Regenerative Science and Medicine. The researchers have successfully halted progression of the disease.
Duchenne Muscular Dystrophy is a severe form of muscular dystrophy that causes muscle weakness and progressive muscle degeneration due the absence of a protein called dystrophin. Dystrophin is responsible for keeping muscle cells intact. The disease primary affects boys and one in 3,500 children has the genetic disorder.
Symptoms of the disease start to be displayed between the ages of 3-5, and as the condition progresses, it starts to affect the heart and respiratory muscles. Death is usually caused when the heart no longer has the strength to pump blood round the body or when patients’ diaphragms become too weak for respiration. The disease used to result in death in the late teens, although advances in care have seen patients survive into their 30s or in some cases, into their 40s or 50s. This is largely due to improvements in cardiac and respiratory care.
While there has been extensive research conducted on the disease, there is currently no cure. However, significant progress has been made using the CRISPR gene editing tool and a cure for Duchenne Muscular Dystrophy could be just around the corner.
For the first time, the researchers have been able to halt the progression of the disease in a large mammal, raising hopes that the CRISPR gene editing tool can be used to treat Duchenne Muscular Dystrophy in humans. Rather than managing the symptoms of the disease, the technique tackles the cause of the problem – A defective gene on the X chromosome responsible for the synthesis of the dystrophin protein.
By making a single cut to the DNA the researchers were able to restore functionality of the gene responsible for producing dystrophin and were able to restore dystrophin levels in the muscles and heart to 92% of normal levels, and 58% of normal levels in the diaphragm.
The researchers had previously used CRISPR to repair the DMD gene in mice and in human cells in vitro, although this is the first time the technique has been used to restore dystrophin levels in a larger mammal.
The researchers are continuing their research and need to assess whether dystrophin levels stay at the elevated levels. Further refinement of the technique will also be required before human trials can commence.
The study – Gene editing restores dystrophin expression in a canine model of Duchenne muscular dystrophy – was recently published in the journal Science. DOI: 10.1126/science.aau1549