PCR and Primer Dimer Question

[Rodney Tweten]

Hello,
I was wondering if someone could tell me how much of a problem primer
dimers are in PCR.  I am performing PCR mutagenesis on a gene that is AT
rich (about 70%) and it is almost impossible to get away from primer
dimers.  For instance, the worst case is one where I have 8 bases out of
11 showing hybridization in a 22-mer.  The bases are all A-T pairs. 
Other examples would be 6 out of 7, again all A-T pairs.  I realize that
primer dimers can kill a PCR reaction but can a hot start eliminate this
problem?  Any help appreciated.