S15) Epigenetics

Question 1

Identify the symptoms of Sickle Cell Anaemia

Answer 1

• Anaemia
• Fever
• Severe pain
• Sudden death

Question 2

Describe the treatment for Sickle Cell Anaemia

Answer 2

Treatment usually aimed to limit symptoms and complications

Question 3

Describe the molecular basis for Sickle Cell Anaemia

Answer 3

• SCA is caused by a single DNA mutation, an A to a T in the beta-globin gene
• Glutamate changes to valine in the amino acid chain

Question 4

Both beta globin proteins need to be mutated to cause Sickle cell anaemia.

What does this tell us about the disease?

Answer 4

Autosomal recessive inheritance

Question 5

What is sickle cell trait?

Answer 5

• Sickle cell trait is a milder form of sickle cell anaemia wherein individuals are heterozygous for the mutation
• Increases resistance to malaria

Question 6

Discuss the geographical variation with sickle cell anaemia

Answer 6

• SCA is very rare in non-African populations and common in populations with African ancestry
• Similarity in distribution across populations with malaria endemicity

Question 7

What is epigenetics?

Answer 7

Epigenetics is the study of heritable changes in gene expression that does not involve changes to the underlying DNA sequence

Question 8

What is Huntington’s disease?

Answer 8

Huntington’s Disease in an inherited neurodegenerative disease, involving the death of brain cells

Question 9

Identify 4 symptoms of Huntington’s Disease

Answer 9

• Seizures
• Abnormal gait
• Personality change
• Dementia

Question 10

Describe the molecular basis for Huntington’s disease

Answer 10

Mutation is a short tandem repeat (STR)

Question 11

What pattern of inheritance does Huntington’s disease follow?

Answer 11

Autosomal dominant inheritance

Question 12

How can Huntington’s Disease be detected?

Answer 12

DNA test detection: use a polymerase chain reaction (PCR) to amplify the CAG repeat

Question 13

In terms of Huntington’s disease, what is meant by the term anticipation?

Answer 13

• Age of onset commonly 40-50 (varies)
• Anticipitation is when the age of onset becomes earlier and symptoms become more severe from generation to generation

Question 14

How can age of onset be determined in Huntington’s disease?

Answer 14

• Age of onset is affected by CAG repeat length
• However, there is still a lot of variation as the influence of the age of onset is multifactorial

Question 15

Identify two approaches in which Huntington’s Disease can be treated

Answer 15

We all have the HTT gene and it is turned on in all cells:

• Appproach 1: use a suppressor screen – delete every gene in turn and identify genes that, when deleted, prevent HD.
• Approach 2: chemical inhibition of kynurenine biochemical pathway

Question 16

What are developmental disorders?

Answer 16

Developmental disorders are a group of psychiatric conditions originating in childhood that involve serious mental and physical impairment in different areas

Question 17

Provide the clinical basis for developmental disorders

Answer 17

• Individually rare, but collectively common
• 2-5% of children born with a major congenital malformation or show neurodevelopmental disorder in childhood

Question 18

What causes developmental disorders?

Answer 18

• Environment (infection, maternal alcohol)
• New mutation in a gene