After being designated the scientific breakthrough of the year, the gene-editing tool is showing its worth as CRISPR can fix muscular dystrophy.
- CRISPR-Cas9 was the scientific breakthrough of 2015
- Muscular dystrophy affects 1 in 5,000 males
- The dystrophin chain can be fixed by removing the defective exon that causes muscle problems
The CRISPR-Cas9 it is a tool which can be used in genetic editing to repair or replace defective genes which could create health problems. Scientists hope to be able to develop cures for genetically transmitted diseases by editing the part of the DNA that is malfunctioning.
So far, they managed to find a way to treat muscular dystrophy in mice. The Duchenne muscular dystrophy is a genetically transmitted disease which usually affects male newborns, about 1 in 5,000. The defective gene is transmitted through the X chromosome. This means that there is a slight possibility girls with two X chromosomes would have at least one copy of this gene.
Symptoms of the disease appear when the child is between 3 and 5 years old and the disease progresses so fast that by the time they are 12 most of them are not able to walk anymore and they will eventually need help with their breathing. For Duchenne muscular disease the life expectancy is up to 30 years.
What causes the disorder is the absence of a protein chain called dystrophin that contains about 80 exons. Exons are protein-coding regions and if one of them is mutated, the whole chain doesn’t get built. Without this chain the muscles deteriorate.
A team of researchers from Duke University used Crispr-Cas9 to fix the DNA problems of muscular dystrophy. The CRISPR tool scans the genome for defects and the Cas9 protein cuts through the DNA removing the defective gene.
To figure out whether they could cure the disorder, the scientists used genetically mutated mice and looked for their dysfunctional exon, removing it. The remaining gene naturally repaired itself and although it was shortened it proved to be fully functional.
During the study, the mice’s heart function also improved. However, compared to the mice that didn’t have the disease, the ones with muscular dystrophy, although they had their genes edited, they still performed worse in muscle tests.
This means that although it worked, it is not a cure yet. However, it could become part of a treatment and scientists will keep working on it to improve the technique and why not, even create a real cure.
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