Immune Systems Holding Back Popular Gene Therapy Technique

Gene therapy is effectively being able to snip out unwanted genes and replacing them with a set of genes for more desirable traits. In a dream world, you could go to the nearest "gene therapist" and have them change any genetically controlled trait you might want removed or altered. People would be able to remove genes that make people more prone to particular diseases and disorders, change the color your hair is when it grows, increase intelligence, etc. with no repercussions. Currently, one of the most popularly experimented with methods is called CRISPR-Cas9, which ScientificAmerican recently reported on. CRISPR is a bacterial defense system which can be "programmed" to find and edit particular gene stretches. Cas9 is the enzyme attacks the target DNA and cuts it out. Cas9 has been effective in mice, but in recent experiments, CRISPR-Cas9 has been seen to trigger immune responses in mice. This isn't because CRISPR-Cas9 is dangerous, but rather, is due to what the Cas9 enzyme is derived from. As of right now, Cas9 is derived from either staphylococcus aureas or streptococcus pyogenes bacteria, more commonly referred to staph infection and strep throat. While Cas9 isn't dangerous in itself, organisms previously exposed to staph or strep may have antibodies that recognize it from past experiences. When this happens, Cas9 causes an immune response from the subject which could have adverse affects if it occurs in a human. Given that most adult humans have had at least strep or staph at some point in their lives, it seems that in its current state, CRISPR-Cas9 is probably not safe for human use yet. The idea has tons of potential, and hopefully, scientists can find ways to derive Cas9 from bacteria that won't trigger immune responses in humans...or mice.