A phenotype consists of only those traits or antigens that can be directly typed, whereas a genotype is the sum of all genes a person has inherited within a blood group system.
Table 4-5 shows ABO phenotypes and possible genotypes if only O, A, and B genes are considered.
|A||AA or AO|
|B||BB or BO|
However, if A1 and A2 subgroups are considered, the phenotypes and genotypes of group A are expanded (Table 4-6).
|A1||A1A1 or A1O or A1A2|
|A2||A2A2 or A2O|
Note: The A1 and A2 phenotypes are denoted by using subscripts. Genotypes are denoted by using superscripts.
|Phenotypes and Genotypes|