1. Is it possible to tell from the pedigree whether inheritance of the PSEN1 gene mutation is dominant or recessive? Explain your answer.

2. Is it possible to tell from the pedigree whether inheritance of the PSEN1 gene mutation is autosomal or sex-linked? Explain your answer.

3. The PSEN1 gene mutation in this study was previously determined to be autosomal dominant. Knowing this, would the mother of the unaffected child in generation III (white square) be heterozygous or homozygous for the mutation? Explain your answer.

4. Give the probability of having offspring without the mutation in the following scenarios:

1. One parent is homozygous for the mutation and the other parent does not have the mutation.
2. One parent is heterozygous for the mutation and the other parent does not have the mutation.
3. Both parents are heterozygous for the mutation.

5. Is it possible to determine from the pedigree when the PSEN1 gene mutation first occurred? If so, how? If not, why not?

6. How was it possible for the scientists to construct this pedigree when the majority of family members are deceased and their DNA is not available for analysis?

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