Question

SET 2

By now, you are hopefully aware that there are at least 3 genes (D, H and I) that work together to determine
someone’s blood phenotype. Assume that Tony, whose genotype is DdhhI A i mated with Mary, whose genotype
is DdHhI B I B .
a) What is the expected phenotypic segregation for their progeny? Show your work and clearly indicate your
final answers
b) Which of the progeny would be able to receive blood from their mother (Mary)? Clearly draw stars next to
those progeny who could receive from their mother.

Answer 1

There are three genes that determine someone's blood group. They are D, H , I

DD & Dd = Rh +

dd = Rh -

hh = Bombay blood group and it can only receive blood from individuals having Bombay blood group phenotype.

Genotypes Blood group

IA IA , IA i = A

IB IB , IB i = B

ii = O

Genotype of Tom = Ddhh IA i

Genotype of Marry = DdHh IB i

So the gametes formed by Tom are :-

• DhIA
• Dhi
• dhIA
• dhi

And the gametes formed by Marry are :-

• DHIB
• DhIB
• dHIB
• dhIB

Offsprings :-

Punnett square

a) The phenotypes can be :-

• AB +
• B +
• AB -
• B -
• Bombay phenotype (having hh gene)

Bombay blood group donot have H antigen so have H antibody. H antigen is required for expression of A and B antigen. So a person having hh gene then ABO donot matter.

b) The progeny that can receive blood from Mary are shown by stars in the table. They should be either AB + or B+ . She cannot donote blood to AB - , B - and Bombay blood group (having hh genotype). The offsprings who can receive blood from Marry are :-

• DDHh IA IB (AB +)
• DdHh IA IB (AB+ )
• DdHh IA IB (AB+ )
• DDHh IB i (B+ )
• DdHh IB i (B+)