open my $inFile, '<', "MOUSE_TF1.txt" or die "Failed to open MOUSE_TF1.txt: $!";

##</code><code>##

use warnings;
use strict;

open my $inFile, '<', "MOUSE_TF1.txt" or die "Failed to open MOUSE_TF1.txt: $!";

my %families;
my @fields = qw(chr start end symbol strand);

while (<$inFile>) {
    my $line = $_;
    chomp ($line);

    my @Gene_Info = split "\t", $line;
    my $id = shift @Gene_Info;

    @{$families{$id}}{@fields} = @Gene_Info;
}
close $inFile;

# select Gene Symbols belonging to "Hox" family and print
foreach my $key (keys %families) {
    if ($key =~ /Hox/) {
        print join ("\t", $key, @{$families{$key}}{@fields}), "\n";
    }
}