HHMI PEDIGREE ANALYSIS EXERCISE

Bolded Selections Indicate Response(s) Selected:

Q1. Individual II-5 in the pedigree shown to

the right is:

A) A male who does not exhibit the trait.

B) A father.

C) Has three affected siblings.

D) All of the above.

Q2. This disease is very severe and strikes early in childhood.

A) True

B) False

Q3. This large pedigree shows a dominant trait because:

A) Mostly males are affected.

B) The family is very large.

C) The trait shows up every generation.

D) Filled symbols always show dominance.

Q4. What might account for the increasing severity and earlier onset of SCA1 each

generation?

A) There’s toxic waste in the town that is getting worse each year.

B) Doctors have become more aware of SCA1 and are diagnosing the disease in

children earlier than they did in the past.

C) People in the town are using their nervous systems in more challenging ways,

making symptoms seem more severe.

D) The mutation in the SCA1 gene is dynamic and changes each generation to

cause a more severe form of the disease.

Opinion Poll 1. Since there is no cure for SCA1, why should family members be

encouraged to have a genetic test?

A) Because having the genetic data from these families will help research into the

disease.

B) Early detection of the disease can help families cope better with affected

relatives.

C) The information could help individuals decide about marriage and children.

D) Relatives should not be encouraged to take a genetic test for mutated SCA1

Opinion Poll 2. The girl should:

A) Tell her sibs to get an APC gene test.

B) Suggest to her sibs that they visit her genetic counselor.

C) Show them the scary pictures from her endoscopy.

D) Keep her FAP diagnosis private from her family.

Q5. Why does FAP appear to be dominant?

A) Although individuals inherit only one mutant copy of APC, the odds of a

mutation occurring in the other copy are high.

B) The pedigree is small, and looks dominant because of random chance.

C) The father inherited a particularly bad form of the gene.

D) The siblings were probably raised in an environment with many cancer-

causing agents.