Professor Judith Rapoport discusses the issue of how copy number variants arise. Some are inherited and others are de novo (first occurrence).
Well, yes in some cases, what’s so interesting in the New England Journal article on the 16P deletion that they say is accounting for – this was a group, I think, from the Broad Institute, where Welch was the first author – they described about eight cases, and half of them were inherited and half of them were de novo. So, that site is important, but it’s hard to understand that. In some cases it’s present in the family and in some cases it’s not. So you really don’t know how penetrant that is, how strong the effect is.