Ms Vicky McGrath:

We take that figure from data from throughout Europe. A system in Europe called Orphanet provides information and collects all the data throughout Europe on the incidence and prevalence of various conditions. We take that figure as the average from a European standpoint, which is between 6% and 8%, and we have lobbed ourselves towards the lower end.

Realistically, all conditions will become rare conditions in the long run as a further understanding of how genes play a role in different "common" conditions is elucidated in future. We no longer talk about cancer, for example, but rather cancer of different organs and specific types of cancer, such as the BRCA mutation and so on. Slowly but surely, our understanding of conditions will build. The definition of rare conditions as those whose incidence we describe as occurring in fewer than one in 2,000 people is just a benchmark. It is a line in the sand that we use to try to understand how many people are living with rare conditions and what is going on with them.