for my $key ( keys %hash ) {
 while ($file2){
   if (
    / \a
    .*?\t  # field  1 of file 2
    .*?\t  # field  2 of file 2
    .*?\t  # field  3 of file 2
    .*?\t  # field  4 of file 2
    .*?\t  # field  5 of file 2
    .*?\t  # field  6 of file 2
    .*?\t  # field  7 of file 2
    .*?\t  # field  8 of file 2
    .*?\t  # field  9 of file 2
    .*?\t  # field 10 of file 2
    $key \t
    .*?\t  # field 12 of file 2
    .*?\t  # field 13 of file 2
    .*?\t  # field 14 of file 2
    .*\z   # field 15 of file 2
    /x) 
      { do something...}
  else {next}
}