Question

1. Jes is planning to get pregnant using sperm from a sperm bank.  The sperm bank does genetic carrier testing on all donors as a policy.  Her [anonymous] donor is a carrier for Maple Syrup Urine Disease (MSUD).  MSUD is a severe recessive metabolic disorder, with a general population carrier frequency of 1/80.  
   1. What is the chance that Jes is a carrier for MSUD? [4 points]
   2. Assuming that she is not a carrier, what is the chance that her baby will have MSUD?  [4 points]
   3. Assuming that she is a carrier, what is the chance that her baby will have MSUD?  [4 points]
   4. Would you advise Jes to get genetic carrier testing (cost is $100 out of pocket) before she purchases this sperm?  Why or why not? [ 4 points]

Answer 1

a. Carrier frequency is 1/80. so Jes has 1.25% chance of being a carrier.

b. If she is not a carrier, the chance is nil (0%) that his baby will have the MSUD. As this s a recessive trait, two alleles must be present to be affected. As Jes is not a carrier, he will always give normal alele to his baby and this will cause birth of a normal baby.

c. If Jes is carrier, there is 25% chance of getting affected baby with MSUD. As her donor is also a carrier, there is 25% chance that two allele for MSUD comes together in the baby .

d. Yes. I strongly recommend that Jes should get genetic testing. As her donor is a carrier for MSUD, there is 25 % chance of getting affected child if Jes is carrier. So, she must take genetic testing before purchasing the sperm