TLS Online TPP Program

#Question id: 12493


Cystic fibrosis shows autosomal recessive inheritance with an incidence of 1 in 2500. The unaffected brother of an affected girl is referred for genetic counseling. Assume that the population is in Hardy-Weinberg equilibrium. Which of the following is correct?

#Unit 8. Inheritance Biology
  1. The probability that the brother is a carrier is 1/2.
  2. If the brother has a child with a healthy unrelated partner the probability that the child will be affected is 1 in 150.
  3. If the brother has a child with his first cousin the probability that the child will be affected is 1 in 12.
  4. If the affected sister has a child with her first cousin the probability that the child will be affected is 1 in 4.