Chapter 4, Problem 47P

The pedigree that follows shows the inheritance of various types of cancer in a particular family. Molecular analyses (described in subsequent chapters) indicate that with one exception, the cancers occurring in the patients in this pedigree are associated with a rare mutation in a gene called BRCA2.

a.	Which individual is the exceptional cancer patient whose disease is not associated with a BRCA2 mutation?
b.	Is the BRCA2 mutation dominant or recessive to the normal BRCA2 allele in terms of its cancer-causing effects?
c.	Is the BRCA2 gene likely to reside on the X chromosome, the Y chromosome, or an autosome? How definitive is your assignment of the chromosome carrying BRCA2?
d.	Is the penetrance of the cancer phenotype complete or incomplete?
e.	Is the expressivity of the cancer phenotype unvarying or variable?
f.	Are any of the cancer phenotypes associated with the BRCA2 mutation sex-limited or sex-influenced?
g.	How can you explain the absence of individuals diagnosed with cancer in generations I and II?