Editing DNA profiling (section)

===Degraded DNA===
Before modern PCR methods existed, it was almost impossible to analyze degraded DNA samples. Methods like restriction fragment length polymorphism (RFLP), which was the first technique used for DNA analysis in forensic science, required high molecular weight DNA in the sample in order to get reliable data. High molecular weight DNA, however, is lacking in degraded samples, as the DNA is too fragmented to carry out RFLP accurately. It was only when polymerase chain reaction techniques were invented that analysis of degraded DNA samples were able to be carried out. Multiplex PCR in particular made it possible to isolate and to amplify the small fragments of DNA that are still left in degraded samples. When multiplex PCR methods are compared to the older methods like RFLP, a vast difference can be seen. Multiplex PCR can theoretically amplify less than 1&nbsp;ng of DNA, but RFLP had to have a least 100&nbsp;ng of DNA in order to carry out an analysis.<ref name="Forensic DNA Typing">{{cite book | vauthors = Butler J |title=Forensic DNA Typing |date=2001 |publisher=Academic Press | chapter = Chapter 7 |pages=99–115}}</ref>