How is gene therapy different than making a transgenic organism?

Question: How is gene therapy different than making a transgenic organism?
- Keywords:
  biology,
  gene therapy
Asked by rhooper821 to Ben, Dave, Ed, Sam, Susana on 18 Jun 2013.
- Benjamin Hall answered on 18 Jun 2013:
  
  In short: it isn’t.
  
  Gene therapy is one of the many applications of the process known as genetic engineering. When gene therapy is used, a gene is integrated into a human’s DNA. That gene is from ‘outside’ of the genome of the organism it’s being inserted into so is known as a ‘transgene’.
  
  There’s a techincal point that if you introduce the gene to the body cells of the patient, then the gene won’t be stable in the patient so you haven’t really made a transgenic organism. However, if the gene therapy is applied to a sperm or egg cell, or a very early embryo, then you are creating a transgenic organism.
- David Briggs answered on 18 Jun 2013:
  
  I would say they are similar but not the same.
  
  Gene therapy is injecting a gene into an organism to make it make more of the gene product – so only the cells around the injection site are altered.
  
  A transgenic organism is one that is genetically altered before birth, so every cell has the altered copy of the gene.

Question: How is gene therapy different than making a transgenic organism?