Both gene therapies and gene editing seek to correct genetic defects by providing healthy genetic coding into the human genome.
The method used to accomplish this differs between the two. Let's imagine that a gene on chromosome 7 has a genetic "glitch" compared to the typical human genome; this particular glitch occurs at a point that codes for a protein which results in cystic fibrosis, a life-threatening disorder that damages the lungs and digestive system.
For decades, scientists have tried to determine how to "reprogram" these faulty genes so that the genetic miscoding is corrected, thereby improving the health of affected individuals. In recent years, much progress has been made in the areas of gene therapy and gene editing.
Gene therapy involves using a vector to introduce "corrected" genes into cells. Scientists often use a virus, remove its genetic ability to cause sickness, and then insert the needed genes into the shell of the virus. This vector then carries the healthy gene into cells.
Genetic editing has gained a great deal of momentum lately, particularly with the development of CRISPR-Cas systems. Using various techniques, scientists are able to "snip" out a problematic section of genetic coding and replace the "glitch" with healthy, typical coding. This therefore removes the problematic genetic coding from the genetic sequence.
Because it targets a specific sequence of genetic coding, gene editing would be most useful to treat genetic illnesses which result from a straightforward genetic substitution or omission, such as sickle cell disease. Other illnesses, such as schizophrenia, which can result from various genetic coding sequences, would be much more difficult to target with gene editing.