CRISPR, which stands for Clustered Regularly Interspaced Short Palindromic Repeats, is a gene editing tool comprised of DNA sequences from prokaryotes, that is becoming more commonly used to treat and potentially cure life-threatening diseases that have previously been viewed as a death sentence; in December of 2022, a study was conducted at the University of California San Diego School of Medicine, where it was discovered that CRISPR technology can be used to target the gene that causes Huntington’s Disease.
First, we must understand what exactly Huntington’s Disease is. Huntington’s Disease, which was discovered in 1872, is a rare neurological disorder characterized by the gradual destruction of nerve cells in the brain. It is caused by a single defective gene, and this mutation is as dangerous and tragic as it is rare; the disease has no cure, and patients typically do not survive beyond 20 years post-diagnosis.
However, thanks to CRISPR, it is a very real possibility that that will soon change.
The study that was conducted at U.C. San Diego involved the experimentation of Cas13d – an RNA editing technique – against toxic RNA and protein buildup that is associated with the HTT gene mutation that causes Huntington’s Disease, and the trial was found to be successful in terms of eliminating that buildup. The experiment was conducted on mice, and it was also discovered that only one injection of the Cas13d therapy was necessary to yield results, and the benefits (improved motor function, lessened symptoms) lasted for eight months.
This discovery is especially fascinating as it connects to our AP Biology units in terms of mutations: The most common genetic mutations are insertions, substitutions, and deletions. The mutation that causes Huntington’s Disease, however, fits into neither one of these categories: if anything, the mutation is considered a duplication, as it is characterized by the unwanted repetition of cytosine, adenine, and guanine; these repetitions are what lead to the protein buildup, and damage the HHT gene.
In previous years leading up to the U.C. San Diego experiment, trials conducted to target the gene that causes Huntington’s Disease have mostly been unsuccessful, but we can hope that this new discovery is a step in the right direction and may provide the key to figuring out how to treat this disorder that has historically been viewed as a death sentence.