For the following question, you are encouraged to refer to the American Pregnancy Association article, “In Vitro Fertilization: IVF,” and the Multimedia presentation, “The Marvel of Prenatal Development,” listed in the Resources.

• What are the similarities and differences between natural conception and in-vitro fertilization (IVF)?

Genetics

For the following questions, you are encouraged to refer to the following materials listed in the Resources: the “Human Genetics” chapter in the Ahluwalia e-book; the “Genes in Pedigree” chapter in the Strachan and Read Internet resource; the “Human Pedigree Analysis” chapter in the Griffiths, Gelbart, Miller, and Lewontin Internet resource; and the “Genetic Counseling” Internet article from the Nemours Foundation.

• How are chromosomes passed down from parents to children? Why is the haploid number of chromosomes from the egg and the sperm important in order for a child to have the correct number of chromosomes? What could happen if a child has less or more than 46 chromosomes?
• How are Punnett squares useful in determining how genes are passed down from each parent to a child?
• What is a family pedigree? How are family pedigrees used to determine the chances of familial genes being passed down to offspring? How could a genetic counselor use a family pedigree to advise parents about the chances of a child inheriting familial genes?

• Scenario One – Our patient seeks genetic counseling

  Kayla has a family history of Duchenne muscular dystrophy (DMD), which is a sex-linked trait. The patient wishes to know her risk of having an affected child. Her grandmother was a known carrier. DMD is an inherited disorder that involves progressive muscle weakness. It affects approximately 1 in 3500 male births worldwide and is inherited in an X-linked recessive pattern.
  Click here to learn more about DMDThe following pedigree was drawn up by the genetic counselor. Our patient, Kayla, is #13.

  

  What are the relationships between:

  1 and 2	1 and 5
  1 and 10	6 and 7
  4 and 5	5 and 8
  8 and 10	1 and 3

  What are the chances her mother was a carrier?
  

  What are the chances our patient is a carrier?
  

  What are the chances she passes the syndrome to a male child?
  
  

  Testing would establish her status as either a carrier or a noncarrier.

  If she is a carrier what are the chance of her having an affected child?
  

  If she is not a carrier what are the chance of her having an affected child?