A CRISPR activation technique has been shown to improve the symptoms of muscular dystrophy disease in mice.

Muscular dystrophy is a hereditary condition characterised by progressive weakening and wasting of the muscles. A specific type of muscular dystrophy is caused by mutations in the gene Lama2, which codes for the protein laminin. Mutations in the Lama2 gene can cause the loss of myelin, the protective covering of nerve cells, which can heavily destabilise muscle fibres.

Another gene that codes for laminin, Lama1, has been shown to reduce muscular dystrophy symptoms when it is overexpressed. However, as lama1 is a large and complex gene its expression is usually difficult to control.

The CRISPR activation technique has shown promise in controlling Lama1 expression. The CRISPR/Cas-9 system was used to insert a short promoter sequence before the Lama1 promotor gene. In mice with the muscular dystrophy mutation but without the symptoms, the CRISPR activation system was able to prevent the onset of muscle fibrosis and paralysis.

The CRISPR activation was then delivered to mice who already had muscular dystrophy. The symptoms improved and the disease onset was reversed.

The CRISPR activation technique is believed to be safer than other gene editing techniques, as unlike the usual CRISPR/Cas-9 system it does not cause breaks in the DNA. However, the risk of the technique causing mutations in genes other than the ones it is targeted to must be considered before testing in humans.

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