Download 3. How are Connie and Derek related to each

GENETICS PERFORMANCE TASK
Name ________________________
Pd _________
NGS Standards:
HS-LS3-1.
Ask questions to clarify relationships about the role of DNA and
chromosomes in coding the instructions for characteristic traits passed from parents to offspring.
HS-LS3-2.
Make and defend a claim based on evidence that inheritable genetic
variations may result from: (1) new genetic combinations through meiosis, (2) viable errors
occurring during replication, and/or (3) mutations caused by environmental factors.
HS-LS3-3.
Apply concepts of statistics and probability to explain the variation and
distribution of expressed traits in a population.
Introduction:
You are a genetic counselor who specializes in family history and disease heredity. A young
couple, William and Connie come to your office seeking a consult regarding their family history
with a disease called Fanconi Anemia. Individuals with this disease can experience affects in
many parts of the body, including bone marrow failure, physical abnormalities, organ defects,
and an increased risk of certain cancers. While this disease is rare (1 in 160,000 people),
William and Connie both have a family member with the condition and they are concerned about
the risk of their own future children inheriting the condition.
Family History:
William’s family:
· William’s parents, John and Florence, had four children.
· William is the eldest.
· His sister Martha, is the second eldest. She is divorced to Jim. They never had any children.
· Paul, the third child, married Bonnie. Together they had two healthy girls: Gretchen and
Stephanie.
· Dan is William’s youngest sibling. He also married and he and his wife, Terri, had two
children: Susan the oldest and Michael the youngest. Michael, who is five years old, suffers
from serious affects due to Fanconi Anemia.
Connie’s family:
· Connie’s parents, Louis and Lenora are deceased. Together, they had three daughters.
· Ann is the oldest daughter. She has never married or had children.
· Connie is the middle child.
· Cathy is the youngest child. She and her husband, Bob, have two children: Lindsay (oldest)
and Derek (youngest). Derek is normal, however Lindsay has Fanconi Anemia and is scheduled
for a bone marrow transplant next month.
1. Use the family history above to create a genetic family pedigree for William and Connie’s
family. Shade in the shapes that represent individuals who have Fanconi Anemia.
2. How does this disease appear to be inherited? (dominant, recessive, sex-linked, etc.)
3. How are Connie and Derek related to each other?
4. If William and Connie are both carriers for the Fanconi Anemia gene, what is the probability
that a child of theirs will have Fanconi Anemia?
5. If William and Connie have a healthy baby, do they still need to be concerned about Fanconi
Anemia for their future children? Explain your answer.
Use A, a alleles for the questions Punnett Square below.
6. Show a punnett square that shows Cathy and Bob as the parents. Circle the box(es) that
show possible genotypes for Lindsay. Put an X through the box(es) that show possible
genotypes for Derek.
7. Fill out the chart below for family member genotypes and phenotypes.
Family Member
Genotype (AA, A?, Aa, aa)
Phenotype (healthy or FA)
Dan
Paul
Lenora
Michael
Cathy
8. Most of the cases of Fanconi Anemia can be traced to mutations in one of 3 different genes:
FANCA, FANCC, and FANCG. Several of the people in the family wish to be tested for the
mutation. Below are the results from sequencing the FANCC gene on each of their #16
chromosomes.
Family Member
FANCC gene sequence
Lenora
Chromosome 16.1
Chromosome 16.2
TTA GGG CAC CCG TAC GTC GCT
TTA GGG CAC GCG TAC GTC GCT
Terri
Chromosome 16.1
Chromosome 16.2
TTA GGG CAC GCG TAC GTC GCT
TTA GGG CAC CCG TAC GTC GCT
Louis
Chromosome 16.1
Chromosome 16.2
TTA GGG CAC CCG TAC GTC GCT
TTA GGG CAC CCG TAC GTC GCT
Ann
Chromosome 16.1
Chromosome 16.2
TTA GGG CAC CCG TAC GTC GCT
TTA GGG CAC CCG TAC GTC GCT
Lindsay
Chromosome 16.1
Chromosome 16.2
TTA GGG CAC GCG TAC GTC GCT
TTA GGG CAC GCG TAC GTC GCT
Use the DNA sequences above to answer the following questions:
9. According to the samples above, what appears to be the normal (unmutated) sequence of
the FANCC gene?
10. Which of the following describes the mutation?
a. A substitution of cytosine with guanine
b. A deletion of a cytosine base
c. A substitution of adenine with guanine
d. An insertion of a cytosine base
11. Which of these is the best description of Louis’ genotype?
a. homozygous recessive
b. homozygous dominant
c. heterozygous
d. There is not enough information to determine.
12. Which of Terri’s chromosomes carries the mutation for Fanconi Anemia?
13. According to the samples, which parent did Terri receive the mutation from?
14. If Ann should ever marry a carrier for the disease and have a child, what are the chances
that the child will be affected with Fanconi Anemia? Draw a punnett square to support your
answer.
15. As a genetic counselor, your job is strictly to provide the family with as much information and
facts as you can; however, William and Connie are seeking your advice as to whether or not
you think they should have children. Record your response below using scientific, financial,
social, ethical, etc. considerations to support your answer.