$ perl tst.pl
$VAR1 = {
          'NM_167212' => {
                           'cg' => 'CG32694-RB',
                           'val' => '2'
                         },
          'NM_167210' => {
                           'cg' => 'CG32694-RC',
                           'val' => '2'
                         },
          'NM_167211' => {
                           'cg' => 'CG32694-RD',
                           'val' => '2'
                         },
          'NM_001042886' => {
                              'cg' => undef,
                              'val' => '1'
                            },
          'NM_135492' => {
                           'cg' => undef,
                           'val' => '1'
                         }
        };