Helen O'Neill

Helen O'Neill

Molecular geneticist and lecturer in reproductive science at UCL. Programme Director for the MSc in Reproductive Science and Women's Health at University College London.


  • Thanks for pointing this out Lyndsey, you are right, I believe the diagram was added in the final stages of production to aid the understanding. I don't think there was cross talk about the text! I will contact the team and let them know.

  • At the moment, when the "guide" sequences enter a cell, they are designed with specificity to the part of the gene sequence we wish to target (or change). As you can imagine, with a guide of 20 base pairs, it is possible that the same or a similar sequence would exist elsewhere in the genome (containing approximately 3 billion base pairs) and these may attach...

  • When a person is prescribed a cocktail of drugs, most patients will take these all at the same time- do you not think they should be advised by their physician to take these at different times throughout the day to avoid such polypharmacy?

  • Thanks for your comment Caroline. You are right, IVF is an incredibly invasive procedure for the mother and embryo, especially when doing PGD. It is not taken lightly though, and is only ever done when absolutely necessary.
    The risk of ovarian hyperstimulation is rare nowadays as each patient has their own individual hormone levels measured prior to treatment...