...CACTCT should have one letter different from the entire text.

One approach would be to replace every position of that sequence with the complementary char set, e.g. /[^C]ACTCT/ for the first position, and then match those six patterns against the entire text. This should allow you to find all substrings which have one letter different.

In reply to Re: finding probes with one mutation ? by almut
in thread finding probes with one mutation ? by hellworld

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