Psychiatric Genetics

Question 1

Psychiatric symptoms of Huntington’s disease?

Answer 1

May be the 1st signs:
• Anxiety
• Compulsions
• Aggression
• Depression
• Blunted affect (decreased affective response, i.e: lack of emotion response)
• Psychosis
• Suicidality

Question 2

Cognitive symptoms of Huntington’s disease?

Answer 2

Decline in executive function, e.g: planning, abstract thinking and cognitive flexibility

Short and long-term memory deficits

Dementia (progressive decline in global function)

Question 3

Motor symptoms of Huntington’s disease?

Answer 3

Choreiform movements

Rigidity

Writhing movements

Problems chewing / swallowing / speaking

Gait disturbance

All actions requiring muscle control may become impaired

Question 4

Inheritance of Huntington’s disease?

Answer 4

Autosomal dominant; if a parent is affected, there is a 50% chance that their child is as well

Question 5

Mutation in Huntington’s disease?

Answer 5

Expansile mutation of the CAG repeat, which encodes poly-glutamine

Results in:
• Toxic effect on cells
• Neuronal loss
• Huntington’s disease

Question 6

What is anticipation?

Answer 6

Phenomenon in which each generation develops a genetic disease at an earlier age that the prior generation

In Huntington’s disease, this occurs because the CAG repeats become longer with each generation

Question 7

Presentation of Huntington’s disease?

Answer 7

Usually asymptomatic until adulthood; they develop slow onset neurological and psychological symptoms

Question 8

Testing for Huntington’s disease?

Answer 8

Genetic testing

Question 9

Treatment of Huntington’s disease?

Answer 9

Currently irreversible

Only symptomatic treatment is available

Question 10

Define dementia?

Answer 10

Progressive decline in global cognitive ability

Question 11

Most common cause of dementia?

Answer 11

Alzheimer’s disease

Question 12

Prominent symptoms of Alzheimer’s?

Answer 12

Short-term memory dysfunction - affects the ability to:
• Learn new things

The following are not as affected:
• Remember things that happened a long time ago (episodic memory)
• Remember facts that were learned a long time ago (semantic memory)
• Carrying out tasks already well-practiced (implicit memory)

Dysphasia, dyspraxia and agnosia

May have mood symptoms, psychosis, behavioural disturbance, cognitive decline

Eventually require full care in later stages of the disease

Question 13

Describe patients with end-stage dementia

Answer 13

Bed-bound and fully dependent patients who have lost the ability to swallow

It is a terminal illness

Question 14

Life expectancy of Alzheimer’s disease?

Answer 14

7 years after diagnosis

Question 15

When should a familial form of Alzheimer’s disease be considered?

Answer 15

If more relatives are affected

If relatives are affected at a younger age

If there are unusual or atypical features

NOTE - most cases of Alzheimer’s disease are multi-factorial, i.e: genetic testing is not predictive

Question 16

Lifetime risk of Alzheimer’s disease?

Answer 16

~10%

If there is one affected 1st degree relative, the risk is 25%

Question 17

Genetics of bipolar disorder?

Answer 17

Strong genetic basis but do not know how it is inherited