Question

Imagine that you are a geneticist at a hospital and you are given a file for a patient
whose family has a history of cancer.
The patient, John Doe, is 18 years old and has had a biopsy done on a tumorous
growth in his adrenal gland. He has a sister, Jane, and a brother, Bob, who are younger
than he is and who are both healthy. His mother, Betty, has a diagnosis of breast
cancer. John’s father, Joe, and John’s paternal grandparents have no history of cancer.
Betty is one of four children. Her brother, Tom, and sister, Lucy, have never had cancer
or signs of cancer. Both Tom and Lucy are older than Betty. Betty had another brother,
Jake, who died very young of leukaemia. Tom has monozygotic twin daughters who are
healthy. Betty’s father, Don, died of soft tissue sarcoma in his thirties. Betty’s mother is
alive and healthy. Betty’s paternal grandmother, Don’s mother, died of a brain tumor in
her thirties. Don had no siblings.

1. (4) Given the family history, you decide to draw a pedigree to help you determine if
the cancer is caused by a heritable genetic defect. In your tree be sure to indicate
John as the propositus and follow other conventions used when making a tree.
2. (1) What is the most likely mode of inheritance of the genetic defect?
As part of your research, you also consult the OMIM (Online Mendelian Inheritance in
Man) database and come up with a short list of candidate genes could mutate to
cause John’s tumor.
MULTIPLE ENDOCRINE NEOPLASIA, TYPE I; MEN1
OMIM #13110
• Associated with tumors of the endocrine (hormone producing) glands. Originally
known as Wermer syndrome.
• Most common tumors involve parathyroid gland, islet cells of the pancreas, and
pituitary gland.
• Other endocrine tumors include adrenal cortical tumors, carcinoid tumors and rare
pheochromocytomas, as well as tumors in other parts of the digestive tract.
LYNCH SYNDROME I
OMIM #120435
• Also known as hereditary non-polyposis colorectal cancer (HNPCC).
• Significantly increased risk of developing colorectal cancer.
• Increased risk of developing other types of cancers, such as endometrial
(uterine), stomach, breast, ovarian, small bowel (intestinal), pancreatic, prostate,
urinary tract, liver, kidney, and bile duct cancers.
LI-FRAUMENI SYNDROME; LFS
OMIM #151623
• Most common types of cancer osteosarcoma (bone cancer), soft-tissue sarcoma,
acute leukemia, breast cancer, brain cancer, and adrenal cortical tumors, which is an
organ on the top of the kidney.
• Increased risk for melanoma, Wilms' tumor, and cancers of the stomach, colon,
pancreas, esophagus, lung, and gonadal germ cells (sex organs) have also been
reported.
CARNEY COMPLEX, TYPE 1; CNC1
OMIM #160980
• Associated with spotty skin pigmentation; myxomas, which are benign
(noncancerous) connective tissue tumors. Tumors can be benign or cancerous.
• Symptoms develop when a person is in his or her early 20s.
• Other common features are Cushing’s syndrome and multiple thyroid nodules
(tumors). Features a combination of weight gain, high blood pressure, diabetes, and
easy bruising, caused by the overproduction of the hormone cortisol.
NEUROBLASTOMA, SUSCEPTIBILITY TO
OMIM #256700
• Solid cancerous tumor that begins in the nerve cells outside the brain of infants and
young children. It can start in the nerve tissue near the spine in the neck, chest,
abdomen, or pelvis, but it most often begins in the adrenal glands.
• Develops most often in infants and children younger than 5.
VON HIPPEL-LINDAU SYNDROME; VHL
OMIM #193300
• Associated with tumors arising in multiple organs. Include hemangioblastomas,
spinal cord, and eye.
• Increased risk of developing clear cell renal cell carcinoma, pheochromocytoma, and
pancreatic neuroendocrine tumor.
• Other features - kidney cysts, pancreatic cysts, epididymal cystadenomas, and
endolymphatic sac tumors.
3. (2) What disorder would you suspect John has based on the information you have
collected? Explain.
4. (1) Based on information from the OMIM database, what gene(s) is most often
associated with this disorder?
5. (2) Should you be concerned about John’s siblings developing cancer? Explain
6. (3) To confirm that John has a mutation in the suspected gene(s), what molecular
technique will you use? What tissue would you use for this test and why?
7. (3) If it turns out that there is a mutation in the suspected gene(s), how can you
experimentally determine that the mutation is located in protein-coding region of the
gene(s)?

Can you answer question 3 and 4?