#!/usr/bin/perl -w
use strict;

my (@a, @b, @c, @d, @e, @f, @g);

while (my $Line = <DATA>) {
    
    my @v = split(/\t/, $Line);
    
    for my $ar ( \(@a, @b, @c, @d, @e, @f, @g) ) {
        my $v = shift @v;
        $v = "NA" unless $v =~ /([A-Za-z0-9-_]+)/;
        push @$ar, $v;
    }
}

use Data::Dumper;

print Dumper \(@a, @b, @c, @d, @e, @f, @g);

__DATA__
a	b	c	d	.	f	g
A	B	C	.	E	F	G

##</code><code>##

$VAR1 = [
          'a',
          'A'
        ];
$VAR2 = [
          'b',
          'B'
        ];
$VAR3 = [
          'c',
          'C'
        ];
$VAR4 = [
          'd',
          'NA'
        ];
$VAR5 = [
          'NA',
          'E'
        ];
$VAR6 = [
          'f',
          'F'
        ];
$VAR7 = [
          'g
',
          'G
'
        ];