The term point mutation originated before the advent of DNA sequencing and therefore before it was routinely possible to discover the molecular basis for a mutational event. Nowadays, point mutations typically refer to alterations of single base pairs of DNA or to a small number of adjacent base pairs. In this section, we shall consider the effect of such changes at the phenotypic level. Point mutations are classified in molecular terms in Table 15-1, which shows the main types of DNA changes and their functional effects at the protein level.
