A panel, which is essentially very dilute genomic DNA, is only good for ONE typing and, even if we use highly multiplexed marker PCR, this would be insufficient in almost every case. We need to find some unlimited way of amplifying the desired content of each aliquot in order that it can be re-typed several thousand times.

Unfortunately, this problem still remains, but several less than perfect workarounds can be used.

Repeat PCR employs frequent interspersed repeats such as the ALU repeats. Primers are designed to amplify between the repeat units effectively amplifying many sections of the genome. Only markers lying between fairly close repeats are amplified significantly.

PEP amplification uses a random primer mix (usually 15-mer) in an attempt to amplify the entire DNA content. In practice, most of the markers are amplified <100 fold and marker specific, highly multiplexed nested PCR, on a sample of the pre-amplified panel, is necessary for marker screening.

Restriction fragment WGPCR is the currently preferred method whereby the aliquots are digested with DpnII and RE site specific primers are ligated to the genomic fragments and used to amplify them through PCR. Only fragments less than 2kb are efficiently amplified and markers need to be screened for lack of DpnII sites.