This question and answer should probably be in Methods&Reagents but
I had the same difficulty with resolving allelotypes of simple
sequence length polymorphisms (SSLPs), some of which differ by just a
few bases. The solution that was suggested to me was to run the
samples on a Formamide/Urea Sequencing gel.
For a 100ml tot vol use:
10ml 38%/2% Acyl/Bis
40ml deionized formamide
H2O to 100mls.
Don't bother to prerun. Use 500microL of 10% APS and 75 microL of