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Year 3 - Genetics > Genetics - Predisposition to Adult Onset Disease > Flashcards

Genetics - Predisposition to Adult Onset Disease Flashcards

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1
Q

why are adults referred?

A
  • Diagnosis
  • Predictive testing
  • Carrier testing or cascade screening
  • Family history (including cancer)
  • Fetal loss or recurrent miscarriages
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2
Q

what are the different mechanisms of adults onset genetic disease?

A
  • Single gene
  • Chromosomal
  • Mitochondrial
  • Multifactorial
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3
Q

The contributions of genetic and environmental factors to human diseases - what conditions are due to genetics and what ones are due more to the environment?

A
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4
Q

The contributions of genetic and environmental factors to human diseases:

genetic or environmental - which is rare and which is common?

A

genetic - rare

environmental - common

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5
Q

The contributions of genetic and environmental factors to human diseases:

genetic or environmental - which genetics is simple?

A

genetic - genetic simple

environmental - genetic complex

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6
Q

The contributions of genetic and environmental factors to human diseases:

genetic or environmental - which is multifactorial?

A

genetic - unifactorial

environmental - multifactorial

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7
Q

The contributions of genetic and environmental factors to human diseases:

genetic or environmental - which has a high recurrence rate?

A

genetic - high recurrence rate

environmental - low reucrrence rate

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8
Q

Single gene disorders with high penetrance - risk estimation _______

A

easier

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9
Q

multifactorial conditions:

  • a polygeneic genetic component interacting with ___________ factors
  • risk estimation more _______
  • Risk ______ being identified for common/mutifactorial disease
  • predictive value of each is very _____
A

environmental

difficult

alleles

small

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10
Q

Principles of Ethics in Medicine - what are they?

A
  • Respect for autonomy
  • Beneficence
  • Non-maleficence
  • Justice
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11
Q

Prediction and uncertainty:

Test information must be usable for _______ or treatment

Susceptibility testing requires adequate information about ________

Predictive testing requires proper _______

Children or adolescents should only be tested if there are potential medical ________

Third parties (employers, insurers) should have no access

A

prevention

uncertainty

counselling

benefits

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12
Q

Summary:

  • The genetic basis of many adult onset disorders is increasingly being elucidated
  • Rapid expansion in gene testing available
  • In future susceptibility testing for common/multifactorial conditions will become possible
  • Social and ethical implications
A
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13
Q

Shared Genetic Heritage

  • Genetic disease affects families, not ___________
  • Discovery of a genetic disorder implies a ____ for _________
A

individuals

risk

relatives

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14
Q

Case 1:

  • 19 year old student, attends alone
  • About to start final year
  • No job
  • No mortgage / insurance
  • Not in a relationship
  • Requesting a gene test for familial motor neurone disease
A

Affected people in each generation

Male to male transmission seen

Autosomal dominant

But – at least 2 non-penetrant individuals

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15
Q

what is the epidemiology of Amyotrophic lateral sclerosis (Motor neurone disease)?

A
  • Generally sporadic (1-2/100,000)
  • Mean age onset 55yrs (younger in familial forms)
  • 5-10% familial (AD +AR)
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16
Q

what are the clinical features of Amyotrophic lateral sclerosis?

A
  • Progressive muscle weakness, wasting and increased reflexes (ie upper and lower neurone signs)
  • Limb and bulbar muscles involved
  • Pure motor signs (with fasciculations)
  • Cognition spared
  • Death due to respiratory failure
17
Q

Mutations of the SOD1 gene encoding _______ are found in patients with familial amyotrophic lateral sclerosis (FALS), a progressive and fatal paralytic disease that is caused by the death of motor neurons in cortex, brainstem and spinal cord

A

CuZn SOD (superoxide dismutase)

18
Q

what is the function of SOD?

A

The presence of SOD protects many types of cells from free radical damage that is important in ageing and ischaemic tissue damage

SOD also helps protect cells from DNA damage, lipid peroxidation, ionising radiation damage, protein denaturation………….. and other forms of progressive cell degradation

19
Q

Amyotrophic lateral scoliosis:

Incomplete penetrance…..no certainty even with mutation _______

No ____

No satisfactory ________

A

analysis

cure

treatment

20
Q

What would you want to discuss before offering testing?

A

Inheritance and his risks

Implications of a positive or negative result

Variability of condition

Insurance

Employment

Future children

21
Q

what can you say about this?

A
  • Males are affected in more than one generation
  • No affected females
  • Affected males are linked through unaffected females
  • Males do not transmit to males
22
Q

Case 3:

  • Married lady, 35
  • 2 young children
  • Mother affected by HD (Huntingtons disease)
  • Thinking about another child
  • Wanted to establish own status
A
23
Q

Huntingtons disease:

  • autosomal ________
  • _____ onset
  • Unique mutation identified

…….CAG expansion

A

dominant

Adult

24
Q

whata re the clinical features of huntingtons disease?

A

•Movement Disorder

………..chorea

athetosis

myoclonus

rigidity

25
Q

what cognitive changes happen in HD?

A

poor planning & memory

subcortical dementia (executive function)

NOT classical dementia

26
Q

what personality change shappen in HD?

A
  • Irritable
  • Apathetic
  • loss of empathy - ‘A different person’
  • disinhibition
  • self centred
27
Q

HD causes what psychiatric diseases?

A

depression, paranoia, psychosis

28
Q

what is the onset of HD? and what is the treatment?

A
  • Onset late 30’s early 40’s…….but variable
  • 15 to 20 years duration
  • Fully penetrant
  • No cure
  • Unsatisfactory treatments
29
Q

What are the possible advantages of predictive testing for Huntington’s disease for this lady?

A
  • Uncertainty of gene status removed
  • If negative: concerns about self and offspring reduced
  • If positive:
  • make plans for the future
  • arrange surveillance/treatment if any
  • inform children/decide whether to have children
30
Q

what are the disadvantages of predictive testing if it is positive?

A

removes hope

continues uncertainty (when)

known risk to offspring

impact on self / partner / family / friends

potential problems with insurance / mortgage

31
Q

what are the disadvantages of predictive testing if it is negative?

A

expectations of a ‘good’ result

‘survivor’ guilt

32
Q

Results may affect others - how?

A

What right (if any) do insurers, employers, schools, or other institutions have to ask about genetic tests?

Subject’s duty (?) to share information with relatives who may be at risk

Physician/investigator’s right/duty (?)to inform relatives at risk

33
Q

Prediction and uncertainty - what. nees to be done?

A
  • Test information must be usable for prevention or treatment
  • Susceptibility testing requires adequate information about uncertainty
  • Predictive testing requires proper counselling
  • Children or adolescents should only be tested if there are potential medical benefits
  • Third parties (employers, insurers) should have no access
34
Q

Summary:

  • Many adult onset conditions have a _______ basis
  • Many more are _________ with genetic factors contributing to the risk
  • PPT currently available in single gene disorders
  • _________ testing for common disorders may become possible
  • Genetic diagnoses impact the whole ______
A

genetic

multifactorial

Susceptibility

family

Year 3 - Genetics (3 decks)

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