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Gene Editing Offers Hope For Treating Duchenne Muscular Dystrophy (nytimes.com)
schwit1 writes with news that scientists have used a new gene-editing technique called CRISPR to treat mice with defective dystrophin genes. This is the first time that such a method has successfully treated a genetic disease inside a living mammal. The Times reports: "Three research groups, working independently of one another, reported in the journal Science that they had used the Crispr-Cas9 technique to treat mice with a defective dystrophin gene. Each group loaded the DNA-cutting system onto a virus that infected the mice's muscle cells, and excised from the gene a defective stretch of DNA known as an exon. Without the defective exon, the muscle cells made a shortened dystrophin protein that was nonetheless functional, giving all of the mice more strength."
I know there are concerns around human genetic manipulation, but there are a lot of people suffering in its absence. I'd be willing to take the risk on a therapy like this if I were suffering from a debilitating or fatal genetic illness. Furthermore, I am ready to shoulder my portion of the societal and ethical risks entailed by others testing it.
The practical application of this form of treatment will (as all three papers do) use systemic, viral delivery, meaning all cells will be affected. You can modulate the probability a little by selecting a virus with affinity for particular tissues, but there will still be germline modifications. If you're really worried about that, you make vasectomy a required co-treatment.
It's still a long way from useful. All three papers report similar results: 2-5% changes in the DNA pool; 40-60% changes in the mRNA pool; 20-30% reduction in functional deficits. In a mouse model with a homogeneous genetic defect and without severe pathology
The results are pretty comparable to targeted exon skipping treatments, which started around 15 years ago and have made small human trials without serious adverse results. It's exciting to see research starting to make progress on fixing diseases where the root cause has been known for 40+ years, but the science (nevermind the FDA) is still 10+ years away.