What is gene therapy? How does it work?

What is the appropriate age for gene therapy?

• If there was a gene therapy to dramatically increase the number of serotonin receptors in a person, at what age would it work at all and at what age would it be most effective? Considering neural development at different ages and so on. My, not very educated at all, guess would be to reach peak efficiency you'd need to give it to the mother while pregnant with the baby so it can affect the brain all the way during early development as well, but I have very little knowledge in this area so maybe somebody else could help me with this?

• Answer:

  It can work at any age. There are many subtypes of serotonin receptors (5HT1,2,3,4,5,6,7a/b/c/etc.), all with different signaling cascades. They experience all sorts of fantastic cross-talk with other receptors (mGluRs, AMPARs, NMDARs, other GPCRs). This question is a bit black and white. You modulate receptor densities through up and downregulation all the time. The body is far more stochastic than a straight answer to this question would do justice to.