Genetic Predisposition to adult onset disordres

Question 1

It’s easier to estimate a person’s risk of developing a genetic disorder if it’s based on a single gene and has high penetrance. What are the problems with multifactorial conditions?

Answer 1

Polygenic genetic component means:

• Can’t identify all the risk alleles
• Predictive value of each is small

Interacts with environmental factors so even with genetic testing uncertainty is high

Question 2

Should children be tested for uncertain genetic disorders?

Answer 2

Only if there are potential medical benefits of testing them (in childhood, if they might as well be tested as adults then wait)

Question 3

Do 3rd parties have access to genetic test results?

Answer 3

No! Insurers and employers etc shouldn’t have access to such results

Question 4

What are the guidelines on predictive testing for multifactorial genetic disorders?

Answer 4

1) Test info must be usuable for prevention/treatment
2) Adequate info about uncertainty
3) Proper counselling must be provided re risk, implications and coping with any fear/anxiety

Question 5

Why might we not want to do predictive testing on a patient?

Answer 5

+ve results even with uncertainty:

• Remove hope
• Impacts relationships
• Potential insurance/employment problems
• Stress/anxiety
• ve results:
• survivor guilt (E.g. if sibling tests +Ve)

Question 6

what are some of the advantages for genetic testing?

Answer 6

If positive:

• makes plans for the future
• arrange surveillance/treatment if any
• inform children/ decide whether to have children

If negative:
- concerns about self and offspring reduced

Question 7

what is SOD and in what disease it is significant?

Answer 7

• Cu/ Zn superoxide disputase
• mutation is involved in development of ALS
• in 20% of familial cases

Question 8

what does SOD do?

Answer 8

protects against

• DNA damage
• lipid Peroxidation
• Ionising radiation damage
• protein denaturation

Question 9

How many forms of SOD are there?

Answer 9

3
SOD1: cytoplasm
SOD2: mitochondria
SOD3: extracellular

Question 10

Is ALS AD or AR

Answer 10

AD

Question 11

Is Huntingtons AD or AR?

Answer 11

AD

Question 12

Presentation of Huntingtons

Answer 12

Movement:

• Chorea
• Myoclonus
• Rigidity

Cognitive

• Poor memory
• Unability to plan
• Subcortical dementia

Personality

• Changed
• Apathetic
• Irritable
• Disinhibition

Psych

• Depression
• Paranoia

Question 13

Presentation of ALS

Answer 13

Affects UMN and LMN

• progressive
• bulbar palsy on top of wasting, weakness, loss of reflexes
• Cognition is spared
• Death by respiratory failure