use strict;
use warnings;
use List::Compare;

my $fileData = <<DATA;
IL12::1::287,6,-17,-9,-21,-24,-15,-2,11,4,4,-15,-26,-16,-9,-18,-25,27,17,6,
IL12::1::329,-25,-18,-28,23,17,1,-3,-23,
IL12::1::1108,-8,-21,17,-25,9,-6,-15,4,
IL12::1::1536,-12,-28,23,-12,17,-25,14,19,20,
IL12::1::1591,-17,-23,-7,-19,25,25,-25,-15,-26,23,29,-12,-25,
IL12::1::803,24,-20,-24,12,8,-22,
DATA

my %items;
my $referenceItem = 'IL12::1::287';

open my $inFile, '<', \$fileData;

while (<$inFile>) {
    chomp;
    my ($item, @values) = split ',';

    $items{$item} = \@values;
}

for my $key (sort keys %items) {
    next if $key eq $referenceItem;

    my @common = List::Compare->new ($items{$referenceItem}, $items{$key})
        ->get_intersection ();

    print "Common for $key: @common\n" if @common;
}

##</code><code>##

Common for IL12::1::1108: -15 -21 -25 17 4
Common for IL12::1::1536: -25 17
Common for IL12::1::1591: -15 -17 -25 -26
Common for IL12::1::329: -18 -25 17
Common for IL12::1::803: -24