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In the not so distant future, we will be tackling many diseases and cancers using the newest revolution in biotechnology that involves targeting very specific parts of DNA and then snipping it. One such technique that has taken the biotechnology world by storm is CRISPR which involves the use of a cas9 endonuclease and guide RNA. This complex is recruited to a target sequence and cas9 cuts the desired region that results in a double strand break. With this double stranded DNA break, it can be ligated back together with a method called Non-Homologous End-Joining (NHEJ) to introduce random mutations via insertions/deletions to knock out a specific gene. Another method of repair called Homology Directed Repair (HDR) involves using a repair template that has homology to the flanking region of the double stranded break which results in controlled gene editing allowing researchers to use it for gene knock-out, knock-in, tagging etc. There are other competing methods such as TALENs (Transcription Activator-Like Effector Nucleases) which a French biotechnology company called Cellectis is using to experiment for possible cancer treatment. As mentioned above, CRISPR uses guide RNA to direct DNA breaks where as TALENs employs the use of 18 repeats of 34 amino acids that vary at amino acids 12 and 13 which is the "Repeat Variable Diresidue" or RVD; RVD mediates the DNA binding specificity. (image credit: genecopeia) A pair of TALEN are targeted to opposite sides of a desired break site. Each TALEN is a chimeric protein with Fok I nuclease domain that results in a specific double stranded break. (image credit: genecopoeia) The use of this technology is detailed in article by Business Insider where an infant in the UK named Layla was born with leukemia that had failed to be treated using common cancer treatment modalities such as chemotherapy and bone marrow transplant. Doctors there knew about Cellectis's work with TALENs and reached out as a last ditch effort to save her. Cellectis accepted their request and began her therapy by targeting her T-cells using TALENs to stimulate her immune system to attack the cancer and the result was complete remission. While many people will be weary of the possible abuse of such technologies, they should set those fears aside because it is this type of technology that will one day lead to the precise targeting and elimination of many diseases including cancer. View full article