...
 my $columnID = $column[0];
 foreach ( my $columnID )
 {
  while ( $columnID =~ /(^FBgn\d+)/ )
  {
   my $ID = $1;
   print $ID, "\n";
  }
 }
...

##</code><code>##

c:\@Work\Perl\monks>perl -le
"use strict;
 use warnings;
 ;;
 my $columnID = 'XXX';
 foreach ( my $columnID )
 {
  while ( $columnID =~ /(^X)/ )
  {
   my $ID = $1;
   print qq{$ID \n};
  }
 }
"
Use of uninitialized value in pattern match (m//) at -e line 1.