Large PCR products?

[Joe Miano]

So, I know most everyone must have, at some point, experienced these large
PCR artifacts (several kb) when PCRing what should only be a few hundred
bases.  Can someone comment on the identity of these products and how they
arise.  We're mapping intron exon boundaries and in some cases find it
impossible to distinguish between several bands (although one band, the
correct one?, is clearly more intense).  I suppose hybridizing with an
internal primer won't help, or will it??

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