For AGRTGA, I used String::Substrings. 
#!/usr/bin/perl

use strict;
use warnings;
use String::Substrings;

my @trip = substrings 'AGRTGAXWXX', 6;
print "$trip[0]\n";

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In reply to Re: substring selection from a string on certain qualifying conditions by Khen1950fx
in thread substring selection from a string on certain qualifying conditions by BhariD

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