A new CRISPR method for manipulating genetic material in cells could correct the "mistakes" responsible for half of all genetic diseases, according to new studies.
Genetic engineering technology allows scientists to edit parts of the genome by removing, adding or changing DNA sequences. CRISPR is not a perfect method and the approach can cause unwanted mutations. Two new studies now allow scientists to tag and change a single mark in the DNA database.
American researchers at MIT and Harvard no longer target changes in DNA to a greater extent than in RNA because they have different structure and function, according to the research.
DNA consists of the sugar deoxyribose, not ribose as is the case with RNA. Deoxyribonucleic acid is responsible for storing and transmitting genetic information, while RNA, as stated in the research, acts as a secondary copy that directly encodes individual amino acids. If they could precisely change individual letters in the RNA sequence, scientists reckon they could reverse disease-causing mutations.
David Lee, who leads the Harvard team of scientists, called this technique "base editing." This way of editing the genome will play an important role in the years to come, the research stated.
Base pairing rules in cells dictate that adenine always pairs with thymine and cytosine with guanine. Li and his colleagues produced an enzyme that targets the base adenine and changes it to a base called inosine, which it reads and marks as guanine. Then the DNA cells try to repair the complementary strand across the gap where the thymine is by inserting a cytosine and then the usual combination of adenine-thymine and cytosine-guanine is obtained.
This type of change occurs in nature and regularly causes disease in humans. Mutation of guanine to adenine is very common and associated with cases of focal epilepsy, muscular dystrophy and Parkinson's disease. According to the results of this research, about half of the 32 thousand known mutations in humans can be traced to mutations that change the combination of guanine-cytosine to adenine-thymine.
Another group of scientists had a different way of converting adenine to guanine. In this case, the enzyme PspCas13b, which comes from the Prevotela bacterium, has proven to be the most effective in inactivating RNA. The changes that occur in this case are reversible, unlike the permanent changes that involve DNA editing. Genetic diseases due to changes in bases can be eradicated. Before that happens, scientists need to find the best way for such changes, and the future will be tense, Nedeljnik reports.
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