Dr. Sally Ann Lynch:

On genome sequencing, the new diagnostic tests are fantastic but they come with a caveat. I will outline some numbers for the committee. Everyone listening to the debate is a human being. All of us have 4 billion to 5 billion letters in our genome, but each of us has between 2 million and 3 million changes in our DNA compared with that of the average human being. That is important to note because people can find it difficult to analyse DNA sequences. All of us have so many changes in our DNA that when we see a change, it can be difficult to work out whether the change is causing the disease or whether it is a benign finding.

There are risks of misinterpretation of the DNA that are known about internationally and cause those of us working in this field a great deal of anxiety, with much of our time spent analysing reports and ensuring we are giving the patient the correct diagnosis. As one can imagine, if we were putting Ms Daly, for example, in a clinical trial, we would have to ensure it was the correct clinical trial and the correct diagnosis.

Medicolegally, there have been cases in Norway where women were told they had a breast cancer gene. Subsequently, data emerged that suggested the change in the genes was not causing breast cancer, but people had gone for prophylactic surgery unnecessarily.

Genome technology is fantastic and helps make diagnoses, but because so much of our DNA is different from that of the "normal human", it takes a long time and it is important to have the correct structures in place in a country to ensure there is safety over the interpretation of the tests and the wrong diagnosis is not made.