There are other processes where genetic materials are involved: there may be transcription errors copying RNA from DNA, errors in or incomplete DNA damage repair, there may be defective ribosomal function leading to dysfunctional protein folding and hence cellular dysfunction as a result. Different genes may respond more or less rapidly to changes in the internal environment or may fail to respond all together.

It is worth noting that the categories of a. and b., what are most commonly referred to as genetic disease, are the processes through which evolution occurs, and as such they are expected consequences of the universal process of natural selection.

All the remaining factors develop as a result of external influences with very few exceptions.

All (a-f) are only problematic in certain environments. There may be specific environments where they are not so, but to most people, these population genetics arguments are not much consolation if they have a biological disadvantage.