Extra reading

Question 1

What happens to MLL (human orthologue of trithorax) gene in leukaemia? (5)

Answer 1

• Chromosomal translocations
• Has over 40 gene fusion partners
• MLL-AF9 and MLL-AF4 are the most common
• Associated with poor prognosis
• Observed in acute myeloid and acute lymphoblastic leukaemia

Question 2

What happens to CBP in leukaemia?

Answer 2

• CREBBP gene involved in translocation
• t(8;16) MYST3-CREBBP fusion
• Seen in AML

Question 3

What are examples of imprinting-related genetic disorders? (2)

Answer 3

• Angelman syndrome
• Prader-Willi syndrome

Question 4

What causes Angelman syndrome? (2)

Answer 4

• Deletion of UBE3A gene on maternal chromosome 15 which is imprinted meaning that the paternal 15 can’t compensate for loss of maternal expression
• Can also be caused by uniparental disomy (UPD), 2 paternal 15s and no maternal

Question 5

What causes Prader-Willi syndrome? (2)

Answer 5

• Deletion of section on paternal chromosome 15 which is imprinted meaning that the maternal 15 can’t compensate for loss of paternal expression
• Can also be caused by uniparental disomy (UPD), 2 maternal 15s and no paternal

Question 6

What epigenetic change is observed in glioblastoma?

Answer 6

IRAK3 hypermethylation which causes increased proliferation

Question 7

What are examples of epigenetic modifications in cancer? (2)

Answer 7

• EN1 (regulates growth and proliferation) hypermethylation by up to 60% in human salivary gland adenoid cystic carcinoma
• EN1 and SCTR hypermethylation in colorectal and prostate cancers