Think of the human cell as an organic computer that operates on instructions formed with four nucleotides symbolized by A, C, T, and G. That is how genes are coded. Genes are instructions to the cellular machinery to produce a specific cellular product (an enzyme or protein). These four symbols are similar to the binary symbols “0” and “1” that form the basis of computer software code. Just as the order of zeros and ones in computer software represents a specific digital command, the order of the A, C, T, and G nucleotides in a cell (each gene) represents a specific organic command.
Gene therapy is so effective at curing diseases because it allows us to “edit” a cell’s operating system (its DNA) to insert or delete commands. It operates directly on cellular mechanisms to produce potent therapeutic effects with high specificity and targeting.
In other words, we can now develop drugs that only affect the desired cells in the body and make precise, predictable changes to them. While traditional medicines diffuse indiscriminately through the body, gene therapies are delivered selectively to specific cells and tissues using viral vectors.
The ability to narrowly target the drug to just the cells that need it avoids the failures of most traditional medicines in human trials. Most adverse events that prevent further testing or approval of new drugs are caused by off-target effects in healthy cells that did not need treatment. We can now make more potent drugs with fewer side effects, because the drugs can target diseased cells and avoid healthy tissue.