Cancer Gene Detection Lab
Review of terms:
Germline mutations-
Somatic mutations-
Tumor suppressor gene-
Background:
Hereditary forms of cancer include breast cancer (BRCA1 and 2), colon cancer (HNPCC) and LiFraumeni Syndrome (p53). Li-Fraumeni Syndrome is rare, affecting approximately 400 families
worldwide, and is characterized by an increased risk for multiple cancers affecting brain, bone,
blood, breast, and soft tissues. Another notable feature in family pedigrees include a sarcoma
patient and at least two immediate relatives with other cancers before the age of 45, as well as
multiple cancers in other family members. The gene that is mutated in Li-Fraumeni Syndrome is
p53, a DNA binding protein that is also a tumor suppressor gene. Mutations in p53 that cause
Li-Fraumeni Syndrome inhibit DNA binding and result in an inactive protein. The mutant form
of p53 is the result of a missense mutation, which leads to a novel SalI recognition site in the
central region of the gene. p53 mutations can therefore be diagnosed by performing SalI
digests of patient’s DNA.
Objective:
Use the information provided below to determine if Valerie might have Li-Fraumeni Syndrome.
Your job is to:
1. Establish a family pedigree. Be sure to include the name, age and type of cancer
under each person’s symbol.
2. Use gel electrophoresis to diagnose Valerie’s p53 genotype (normal/normal,
normal/mutant, mutant/mutant) AND to determine whether she inherited a germline
mutation in p53. Be sure to include a tracing of your gel as data! Don’t forget labels!
Name_________________________ Date ________ Period_______ Score _________
Cancer Detection Lab
Family Pedigree:
Gel Tracing:
Valerie’s p53 genotype: ______________________
Describe whether Valerie inherited a germline mutation, and
whether she obtained one or two somatic mutations in her
p53 alleles.
Does this data lead you to believe that Valerie has Li-Fraumeni Syndrome? Why/why not?