Population Genetics: Inbreeding

  • #1

Homework Statement


Dolor and her cousin Largo have conceived a child. They are very concerned about the baby, because they have heard that children of close relatives have a higher incidence of birth defects and/or inherited recessive disorders. They know that their maternal grandmother was a carrier of the Herrera syndrome allele. Assuming that this is the only source of genetic problems for Dolor and Largo, what is the chance that they are both carriers ?
a. 1 in 16

b. 1 in 4

c. 1 in 8

d. 1 in 106

e. 1 in 2



Homework Equations


See below.


The Attempt at a Solution



Each grandchild has ¼ probability of carrying one of four original alleles from grandparents, so the probability of both being carriers is (¼)* (1/4) = 1/16?




Homework Statement


The chance that Dolor and Largo will have a child with Herrera’s
syndrome is
a. 1 in 4

b. 1 in 64

c. 1 in 32

d. 1 in 16

e. 1 in 12




Homework Equations


See below.


The Attempt at a Solution


For the great-grandchild there is a 1/8 probability (of gametes) for getting a recessive allele, so

(1/8) * (1/8) = 1/64?


Thank you for any help.
 

Answers and Replies

  • #2
Moonbear
Staff Emeritus
Science Advisor
Gold Member
11,490
52
Everything sounds right.
 

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