I'm doing research on human DNA which I extract
using Chelex . This DNA extract is concerved in a freezer at -20 C . I kept
it for a month and did 6 analyses with it (so it was defrosted and frozen
six times) I always got results after PCR with primers for 5 STR loci except
last time . Could my sample be degraded or should I search for other causes?
My e-mail adress is Dieter.Deforce at rug.ac.be