HOMOPOLYMER OR REPEATS

Possible Causes:

1) The DNA Sequence Contains a Homopolymer or Repeat: Repetitive elements comprised of a single base or several bases may interfere with the activity of the sequencing enzyme (a modified Taq polymerase), resulting in noise immediately following the repeat.Solutions: While adding formamide or DMSO to the reaction can sometimes work, the best way to get around this issue is simply to sequence from the opposite direction.