Question

Nail patella syndrome is a rare autosomal dominant condition causing misshapen nails and kneecaps. The Nail patella gene is approximately 12 map units apart from the I gene which determines ABO blood type.

• Nail patella syndrome (N) is dominant to normal

• I^A is codominant to I^B; I^A is dominant to i

• I^B is codominant to I^A ; I^B is dominant to i

• I^A I^A and I^A i = Type A blood

• I^B I^B and I^Bi = Type B blood

• I^A  I^B = Type AB blood

• ii = Type O blood

Sam has Nail patella syndrome and Type AB blood, Sam's genotype is I^AN/I^Bn

Tai has Type O blood and normal nails and kneecaps.

What is the chance Sam and Tai's child will have Type B blood and Nail patella syndrome? Answer is given in percent

Select one:

a. 6%

b. 0%

c. 25%

d. 50%

e. 12%

Answer 1

a). 6%

Explanation:

Based on the information, the followings are the genotype of the Sam and Tai.

Sam = I^AN/I^Bn

Tai = in/in

I^AN/I^Bn x in/in ----Parents

Distance between genes (m.u.) = Recombination frequency (%)

12 mu = 12%

I^AN/I^Bn genotype produces 4 types of gametes as below:

Recombinant gametes = 12%

I^An = 6%

I^BN = 6%

Non-recombinant gametes = 88%

I^AN = 44%

I^Bn = 44%

	in
IAn = 6%	IAn / in= 6%---Type A blood and normal
IBN = 6%	IBN/ in = 6%---Type B blood , patella syndrome
IAN = 44%	IAN/ in = 44%-- Type A blood , patella syndrome
IBn = 44%	IBn/ in = 44%--- Type B blood and normal

The chance Sam and Tai's child will have Type B blood and Nail patella syndrome = y%