Exam: Cancer genetics

Questions
1. 90% of patients with chronic myeloid leukemia have a translocation on the chromosome 22. What is this abnormal chromosome referred as? and what is the abnormal protein produced by this chromosome?

2. Burkitt lymphoma is a form of neoplasia seen in children in Africa, it is a lymphoma that involves the jaw. Research shows that 90% of affected children show a translocation of an oncogene, which one?
a. RAS
b. MYC
c. TP53
4. SMAD4

3. Gene amplification is always pathological.
a. True
b. False

4. RAS is a proto-oncogene when activated can lead to proliferation of a cell. In which step of cell signal pathway does RAS have an effect on?
a. Proliferation
b. Differentiation
c. Signal translation
d. Signal transduction

5. Activation of the bcl-2 oncogene through chromosomal rearrangements is associated with inhibition of apoptosis.
a. True
b. False

6. Which one of the following statement is wrong. Two hit hypothesis...
a. is also known as Knudson hypothesis
b. proposes a model in where mutation on both allels is required to develop a malignancy
c. is consistent with LOH (loss of heterozygosity)
d. explains autosomal dominant pattern of inheritance

7. Although the hereditary form of Retinoblastoma (Rb) follows an autosomal dominant pattern of inheritance, at the molecular level it is recessive.
a. True
b. False

8. Loss of heterozygosity can occur through several mechanisms. Which one of following is wrong?
a. Mitiotic nondisjunction
b. A deletion on the chromosome carrying the corresponding allele
c. Cell hybridization
d. Crossover between two homologous genes

9. RB1 (Retinoblastoma 1) gene is a..
a. Tumor suppressor gene
b. Oncogene

10. Li-Fraumeni syndrome is associated with an inherited or germline mutation of tumor suppressor genes, which one? and what is the inheritance pattern of Li-Fraumeni syndrome?

11. Which one of the statement is right?
a. Hypomethylation of an allele results in increased expression of it
b. Hypermethylation of an allele results in increased expression of it

12. What does Loss of Imprinting (LOI) lead to?

13. Sporadic retinoblastoma usually presents as...
a. Bilateral retinoblastoma
b. Unilateral retinoblastoma

14. Colorectal cancer is more than often caused by accumulation of several mutations and deletion, which one of the following gene(s) doesn't usually play a role in development of colorectal cancer?
a. WT1
b. SMAD2/SMAD4
c. RAS
d. APC
e. TP53

15. Which statement about juvenile polyposis syndrome (JPS) is wrong?
a. JPS is caused by SMAD4 mutation.
b. JPS is transmitted autosomal dominant
c. JPS patients usually develop colorectal carcinoma before the age 20.
d. JPS patients present with bleeding with anemia, pain and intussusception.

16. Cowden disease is caused by mutation of a tumor suppressor gene, which one (mainly)?

Fig. 1

17. Figure 1 shows a picture of a patient with dark melanin spots on the lips. Patient also presented with abdominal pain and genetic testing showed mutation of threonine kinase gene STK11 located on chromosome 19p. What is the likely diagnosis?
a. Cowden disease
b. MYH polyposis
c. Juvenile polyposis syndrome
d. Peutz-Jegher syndrome

Answers

1. Philadelphia chromosome, ABL-BCR (fusion) protein.
2. b
3. b
4. d
5. a
6. d
7. a
8. c
9. a
10. TP53 gene, autosomal dominant
11. a
12. Activation of an allele that is normally silent
13. b
14. a
15. c
16. PTEN
17. d