Overview of ABO gene sequence variations observed in this study.ABO*A101 was used as the reference sequence. Point mutations, deletions, and insertions are indicated using different bars. The major ABO alleles are represented by rectangles. Parts of the ABO gene showing identical or closely related sequence motifs are highlighted using the following colors: red, ABO*B; yellow, ABO*O01; teal, ABO*O02; and light blue, ABO*O03. This figure is schematic and the boundaries of the colored areas do not indicate the exact locations of a possible recombination event. indicates deletion; ▪, insertion; |, point mutation.