Reminder on RFLP and SSR analysis (RFLP analysis)

RFLP analysis is the older, and less efficient version of genetic fingerprinting. It uses bacterial enzymes called “restriction enzymes” to cleave your DNA at specific sites called “restriction sites”. Restriction enzymes are hypothesized to be a bacterial counter to viral invasion by cleaving the phosphate backbone of DNA at specific palindromic sequences ranging from 4-12 base pairs (bp) in length. Since human DNA has many of these sites (simply due to statistical chance), treating a sample of human DNA with 1-2 restriction enzymes will create a distinct pattern of bands when the cleaved DNA is separated via gel electrophoresis.

However, since all human DNA is slightly different, and one mutation in the composition of a restriction site can render it into “normal” DNA (and visa versa) very few people have the same pattern of restriction fragments, and application of several different restriction enzymes and use of different segments of DNA will always allow for distinction between two people (unless they’re identical twins) in case the initial results are in doubt. However, this takes time, and some regions mutate quicker then others, so results can take longer to develop and may be more subject to doubt. Thus, another form of genetic fingerprinting has come into favor, which exploits a highly variable segment of DNA.