What about the epigenetic effects of gene therapy?

We posed this question to Professor Adrian Thrasher from Great Ormand Street Hospital and University College London...

Adrian - Epigenetics is increasingly important in our understanding of how genes work. It regulates in some ways how the genes are turned on or off, it's important through developmental processes. It's important in adult cells, in foetal cells. It's also important in gene therapy because we know if we don't get the sequences right, the genes can become epigenetically modified. - so may switch off unexpectedly which is undesirable. It may switch on unexpectedly which is also undesirable. So the epigenetics is important. There's a lot of ongoing work.