use strict;
use warnings;

my $Text="LOC100282561  [Source:RefSeq peptide;Acc:NP_001148941]";
my %VisitedLinks=();

#Searching for NCBI Entrez Gene IDs                                                                                                                                                                       
$_ = $Text;
my @OriginalArray = /(LOC\d{9})/g;
for (my $i=0; $i < @OriginalArray; $i++) {
    if (!defined($VisitedLinks{$OriginalArray[$i]})) {
        $VisitedLinks{$OriginalArray[$i]} = 1;
        my $Link = EntrezGeneLinks($OriginalArray[$i]);
        my $Find = $OriginalArray[$i];
        $Text =~ s/$Find$/$Link/g;
    }
}

print $Text,"\n";

sub EntrezGeneLinks {
    my ($ID) = @_;

    return '<a href="http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&term='.$ID.'" target="_blank">'.$ID.'</a>';
}