Essential Genetics 6th Edition by Daniel Hartl

Exercise 14

The accompanying pedigree includes individuals affected with adenomatous polyposis, and the diagram of the gel shows a restriction fragment from a number of alleles of APC , mutant forms of which are associated with this cancer. Four sizes of restriction fragments (a through d) are observed. Individuals in generations I and II are old enough to have developed the cancer if they carry a mutant APC allele, but the individuals in generation III are all too young to have developed the disease. Identify the high-risk individuals in generation III and those who are not at risk. (Note that a mutant allele and a nonmutant allele can yield the same size restriction fragment.)