More complicated regexes are possible if there are other formulations of XXX&intron that you want preserved. 
#!/usr/bin/perl
use warnings;
use strict;

print grep{!/intron/ unless /splice_region&intron/}<DATA>;

#Update: the English explanation:
# exclude lines with "intron" except if that line
# contains "splice_region&intron". 

=Prints:
whehehe shshshs hshshsh #should pass thru
som splice_region&intron intron 98797 #should pass
wqer splice_region&intron poiy #should pass

=cut


__DATA__
something intron asdfasdf #should be deleted
whehehe shshshs hshshsh #should pass thru
som splice_region&intron intron 98797 #should pass
wqer splice_region&intron poiy #should pass

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In reply to Re: remove lines with exact match only by Marshall
in thread remove lines with exact match only by MilaK

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