Crispr-CAS9 say whaaaatt?!

This article, though hard to understand because of the prolixity and complexity of the subject matter, is still very fascinating! The main focus of the article was to discuss the bright future, and existing challenges of clustered regularly interspaced short palindromic repeat (CRISPR) technology and the importance of developing customizable specificities, such as CAS9, to improve its capabilities.  This technology, when mastered, will enable scientist to target specific gene mutations in DNA, cut out the faulty sequence and insert the correct sequence, thus curing the genetic disease.  Even more exciting, scientists are currently creating large Guided-RNA (gRNA) libraries which will not only be able to target one specific gene mutation, but THOUSANDS all at once! These libraries currently contain about 67,000 to 84,000 separate distinct gRNA’s and have shown to be effective phenotype screens in both human and mouse cells!  This biggest obstacle that the CRISPR-CAS9 developers are facing right now is the effects of “off-target” effects.  “Off-target” effects are defined as nucleotide cleaving at an unintended site of the DNA.  So far, they have found that these effects are much more detrimental if they occur at the 5’-end rather than the 3’-end. So far, the best strategy for preventing these negative effects is to lower the concentration of the gRNA and/or CRISPR-CAS9 being expressed in the human cells.  I, for one, am very excited to see where this technology leads us! https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4022601/