A new approach version of the classic CRISPR-Cas9 gene editing system; that is better at recognizing the disease causing mutation seen in Beethoven mice. The refining tool allowing scientists to selectively disable the defective copy of a hearing gene called Tmc1; while sparing the healthy copy.
By using novel gene editing approach to salvage the hearing of mice with genetic hearing loss; and succeeding in doing so without any apparent off-target effects as a result of the treatment. The researchers report, their system managing to recognize a single incorrect DNA letter in the defective copy among 3 billion letters in the mouse genome.
Gene editing tool
The demonstrating that this more refining; better targetting version of the now-classic CRISPR/Cas9 editing tool achieves an unprecedented level of identification and accuracy. Everyone inherits two copies of the same gene one from each parent. In many cases, one normal gene is sufficient to ensure normal function that spares the individual from disease.
By contrast, in so-called dominantly inherited genetic disorders, a single defective copy can cause illness. The mice carrying the faulty Tmc1 gene are known as Beethoven mice because the course of their disease mimics the progressive hearing loss experienced by the famed composer. The cause of Ludwig van Beethoven’s deafness, however, remains a matter of speculation.
By the classic CRISPR-Cas9 gene editing systems work by using a guiding molecule gRNA to identify the target mutant DNA sequence. Once the target DNA is pinpointing; the cutting enzyme Cas9 snips it. This is because the guide RNA that leads the Cas9 enzyme to the target site and the Cas9 enzyme that cuts the target DNA are not entirely precise and could end up cutting the wrong DNA.
To achieve enhanced accuracy of the detection and disruption, the new; optimized system combines two levels of recognition gRNA to locate the target gene; and a modified form of Cas9 that can pinpoint the specific DNA mutation in Beethoven mice. But advantage of the fact that this system recognizes mutant DNA but not normal DNA and uses a dual recognition system for enhanced precision