You took only exon 6 because the sequence changes that lead to the different blood types occur mainly in this exon, so to determine the different alleles for this trait you actually only need this exon, the rest of the exons are not really informative for this purpose.
File: "DARK BLUE" chromatogram sequence Run Ended: Jul 26, 2003, 1:45:37 Signal G:31 A:18 T:14 C:13...