while (<DATA>) {
   ($1, $2, $3, $4, $5, $6) = split;
   $hash{$1} = [ $2, $3, $4, $5, $6 ];
}

# or, alternatively, a hash of hashes:
   $hash{$1} = {
      reg    => $2,
      score1 => $3,
      score2 => $4,
      score3 => $5,
      score4 => $6
   };

# thus, score3 can be found as such:
   $hash{a}->[3];   # or with the other method:
   $hash{a}->{score3};