Question

The very rare Bombay blood phenotype in humans results in blood type O because of the lack of both the A and B antigens in individuals who are of hh genotype. This genotype results in blood type O regardless of the genotype at the unlinked I locus. If two parents are both of I A I B Hh genotype, what is the probability that their child will have type blood B

Answer 1

Answer:

The probability that the child will have type blood B equals 3/16.

Explanation:

Available data:

• Individuals with the rare Bombay blood phenotype lack both the A and B antigens in individuals and/or are of hh genotype.

• Cross between two parents that are both of I A I B Hh genotype

Cross: IAIB Hh    x    IAIB Hh

Gametes) IAH, IAh, IBH, IBh  

                IAH, IAh, IBH, IBh

Punnett square)        IAH            IAh         IBH         IBh

                   IAH      IAIAHH     IAIAHh    IAIBHH   IAIBHh

                   IAh       IAIAHh     IAIAhh     IAIBHh    IAIBhh

                   IBH      IAIBHH     IAIBHh     IBIBHH   IBIBHh

                   IBh       IAIBHh     IAIBhh      IBIBHh   IBIBhh

F1) Genotype

•     1/16 IAIA HH
•     2/16 IAIAHh
•     1/16 IAIAhh
•     2/16 IAIBHH
•     4/16 IAIBHh
•     2/16 IAIBhh
•     1/16 IBIBHH
•     2/16 IBIBHh
•     1/16 IBIBhh

    Phenotype

•     3/16 Blood type A
•     6/16 Blood type AB
•     3/16 Blood type B
•     3/16 Blood type 0