The following script outputs the expected output in about 2% of runs, because for multiple possibilities, it selects a random one (the first key in a hash). Is it what you want? 
#!/usr/bin/perl
use warnings;
use strict;
use feature qw{ say };

my %relative;
while (<>) {
    my ($close_relative, $of_interest) = /(.*)\((.*)\)/ or next;

    next if $close_relative eq $of_interest;

    undef $relative{$of_interest}{$close_relative};
}

for my $gene (sort keys %relative) {
    say join ' : ', (keys %{ $relative{$gene} })[0], $gene;
}

[download]

It stores the pairs in the %relative hash of hashes in the following way: 

Micmi1_478558 => { Micmi1_311120 => undef },
Thiar1_121068 => { Thite2_36710  => undef,
                   Chagl1_10753  => undef,
                   Spoth2_41043  => undef,
                   Myche1_767736 => undef, }
...

[download]

($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,

[download]

In reply to Re: Perl regex by choroba
in thread Perl regex by Nicpetbio23!

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