Answer
In multiple allele inheritance more than two reciprocal alleles for a single locus are involved in determining a single phenotypic expression. An example of this type of inheritance is exemplified in the transmission of the ABO blood type genes.
Work Step by Step
There are three reciprocal alleles that operate in in the ABO blood type transmission. These may be listed as the IA gene the IB gene and the i gene
The possible genotypic combinations at this locus are IA/IA; IB/IB; IA/IB and i/i. The genes IA, and IB are both dominant and are always expressed; the i gene is recessive
The genotpye ( ABO blood type) that derive from these combinations are :
IA/IA and IA/i---------- A type blood
IB/IB and IB/i------ B type blood
IA/IB -------------------AB type blood
i/i ----------------------O type blood
The "A"gene and the "B" gene are codominant; the "i" gene is recessive.
