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OD1 - Integrated Ophthalmic Sciences & Preclinical Optometry > BS - Genetics of Eye Diseases - Week 3 > Flashcards

BS - Genetics of Eye Diseases - Week 3 Flashcards

1
Q

Do AMD or glaucoma have a genetic component?

A

Yes, they both do.

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2
Q

Name the 6 mendelian inheritance patterns.

A 
Autosomal recessive
Autosomal dominant
X-linked recessive
X-linked dominant
Codominant
Mitochondrial
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3
Q

Name 2 common genetic diseases in school-aged children.

A

Strabismus

Congenital Nystagmus

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4
Q

Is the prevalence of myopia very high, medium, or low in the general population?

A

Very high in the general population

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5
Q

What is the prevalence of myopia like in Aisan populations compared to others?

A

Significantly higher, up to 90%

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6
Q

What is the likely inheritance pattern of myopia (2)?

A

It can be mendelian, but more often inherited as a complex trait.

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7
Q

What percentage of congenital cataracts have a genetic cause?

A

50%

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8
Q

Mutations of genes controlling what mechanisms lead to cataracts (4)?

A 
Lens development (PAX6)
Lens crystallins (CRY)
Gap junctions (Cx43)
Aquaporins
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9
Q

What is the 2nd leading cause of congenital vision loss?

A

Optic nerve hypoplasia

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10
Q

What are the risk factors for optic nerve hypoplasia (7)? What percentage of cases do not have these risk factors?

A 
Preterm birth
Alcohol
Quinine (malaria)
Phenytoin (siezures/cardiac problems)
Maternal diabetes
Congenital cytomegalovirus infection
LSD consumption
70% do not have the above risk factors
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11
Q

What are three symptoms of optic nerve atrophy?

A

Vision loss
Poorer colour vision
Nerve lost tissue, pale

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12
Q

Name the two forms of optic nerve atrophy, and their inheritance pattern.

A

Optic atrophy 1 - autosomal dominant

Lebers hereditary optic atrophy - mutations in mitochondrial DNA

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13
Q

What are the inheritance patterns most colour vision deficiency conditions?

A

X-linked recessive

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14
Q

Name one of the most common retinal degeneration conditions.

A

Retinitis pigmentosa

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15
Q

Define retinitis pigmentosa.

A

A group of many forms of inherited retinal dystrophy, or degeneration.

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16
Q

Mutations to proteins in what 7 mechanisms would result in retinitis pigmentosa?

A 
Phototransduction cascade
Vitamin A metabolism
Cell-cell/synaptic interaction
Intracellular protein trafficking
Cilia maintenance
pH regulation
Phagocytosis
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17
Q

What is a symptom of mutations to RPE65, what is this condition called, and what is its inheritance pattern? When is it typically diagnosed?

A

Blindness with autosomal recessive inheritance
Typically diagnosed within the first few years of life
Also known as leber congenital amaurosis

18
Q

Mutations to how many genes can cause leber congenital amaurosis?

A

> 12 genes

19
Q

What percentage of RPE65 mutations does leber congenital amaurosis account for?

A

6%

20
Q

Name 5 means of subjectively assessing retinal function in retinitis pigmentosa.

A 
Visual acuity
Contrast sensitivity
Flicker sensitivity
Dark adaptation
Visual fields
21
Q

Name 2 means of objectively assessing retinal function in retinitis pigmentosa.

A

Pupil response

Electrophysiology

22
Q

What is the EOG and what is it modified by?

A

The ocular resting potential

It is modified by derivatives of retinol acting on potassium channels in the RPE

23
Q

Name 5 conditions that alter the EOG, and name what specifically they alter, define how its obtained, and the normal value.

A 
Vitamin A deficiency
RPE diseases
Retinal toxicity
Diabetes
Retinal dystrophies
They alter the arden ratio, which is the light peak / dark trough, normally >2.0
24
Q

What does the arden ratio represent?

A

The maximal K+ buffering capacity of the RPE - RPE function.

25
Q

During an ERG, what happens to the radial retinal and lateral currents?

A

Radial retinal currents sum up

Lateral currents cancel out

26
Q

What does the a-wave of an ERG quantify?

A

Phototransduction

27
Q

What does the b-wave of an ERG quantify?

A

ON bipolar cell responses

28
Q

What does a visual evoked potential measure?

A

A response from the visual cortex in response to a visual stimulus (checkerboard pattern).

29
Q

Name 4 applications of visual evoked potentials.

A

Amblyopia
Potential acuity albinism
Intectness of visual pathway (stroke/mass)
Animal axperiments

30
Q

What occurs at the optic chiasm of albinos and what percentage?
What does this result in on a VEP?

A

An abnormal decussation at the chiasm, 55%.

L or R eye stimulation gives an abnormal lateralisation on a VEP signal.

31
Q

How are VEP potential acuity estimates done (2)?

A

Record VEP amplitude to checks of varying size.

Extrapolate aplitude vs check size to baseline (0).

32
Q

What does an ERG a-wave represent if dark/light adapted?

A

Light adapted - cone photoreceptor response

Dark adapted - rod photoreceptor response

33
Q

What does an ERG b-wave represent if dark/light adapted?

A

Light adapted - cone bipolar response

Dark adapted - rod bipolar response

34
Q

What does the c-wave of an ERG quantify?

A

RPE response

35
Q

What does the d-wave of an ERG quantify?

A

OFF bipolar cell response

36
Q

What do the oscillatory potentials of an ERG quantify?

A

Feedback between amacrine, bipolar, and ganglion cells

37
Q

What does the STR of an ERG quantify?

A

Scotopic threshold response

Ganglion cell response

38
Q

What do P50 and P75 on a VEP represent?

A

LGN generator

39
Q

What does P100 on a VEP represent?

A

Visual cortex

40
Q

What does >180ms on a VEP represent (2)?

A

Association areas

Conscious processing

41
Q

Name a potential means of gene therapy for retinal degeneration, and the requirements for it.
Name the method, and how it works and what it involved.

A

If photoreceptors are still there, the deficient gene can be reinserted.
Done using adeno-associated virus (AAV).
It is a small virus that infects humans and primates.
It incorporates its genome into a host cell.

42
Q

Name 4 reasons why adeno-associated virus is suitable for gene therapy use.

A

Not currently known to cause diseases
Causes a very mild immune response
Infects both dividing and non-dividing cells
Incorporates its genome into the host cell

OD1 - Integrated Ophthalmic Sciences & Preclinical Optometry (123 decks)

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