Human Heredity 11th Edition by Michael Cummings

Exercise 30

The following family has a history of inherited breast cancer. Betty (grandmother) does not carry the gene. Don, her husband, does. Don's mother and sister had breast cancer. One of Betty and Don's daughters (Sarah) has breast cancer; the other (Karen) does not. Sarah's daughters are in their 30s. Dawn, 33, has breast cancer; Debbie, 31, does not. Debbie is wondering if she will get the disease because she looks like her mother. Dawn is wondering if her 2-year-old daughter (Nicole) will get the disease.
A) Draw a pedigree indicating affected individuals and identify all individuals.
B) What is the most likely mode of inheritance of this trait?
C) What are Don's genotype and phenotype?
D) What is the genotype of the unaffected women (Betty and Karen)?
E) A genetic marker has been found that maps very close to the gene. Given the following marker data for chromosomes 4 and 17, which chromosome does this gene map to?
F) Using the same genetic marker, Debbie and Nicole were tested. The results are shown in the following figure. Based on their genotypes, is either of them at increased risk for breast cancer?