my (@array);
while(<IN>){
 chomp $_;
 my @cols = split("\t", $_);
 my $data = join("\t", $cols[2], $cols[5]);
 push (@array, {$cols[0]=>$data}); # to keep multiple entries for the same key
}
close(IN);

foreach my $key(@array){
    foreach my $value(keys %$key){
	print $value, "\t", $key->{$value}, "\n";
	#here how can I join values for the same key?
        #similar to OUTPUT shown below
     }
}


INPUT
p1 cis 10
p1 plat 20
p1 gls NA
p2 cis 0
p2 NA 9

OUTPUT
p1 cis,plat,gls 10,20,NA
p2 cis,NA 0,9