DIS - Inherited Retinal Disease - Week 2 Flashcards

1
Q

What are most genetic diseases and how is AMD different to them?

A

Many inherited retinal diseases are monogenic

AMD involves multiple genes, environmental factors, dietary factors, and lifestyle habits

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2
Q

Can the exact same mutations in one gene cause different disease presentations or do they always have the same outcome?

A

Can cause different presentations

-epistasis

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3
Q

Define epistasis.

A

A form of gene-gene interaction in which genes not directly involved in causing the disease have an effect on the phenotypic expression of the disease trait (caused by the mutation in another gene)

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4
Q

What are rod-cone dystrophies?

A

A family of progressive diseases in which rod dysfunction is more severe than cone dysfunction

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5
Q

Can rod-cone dystrophies cause night blindness?

A

Yes

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6
Q

What kind of vision loss do rod-cone dystrophies cause?

A

Peripheral loss

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7
Q

Describe the severity and progression of rod-cone dystrophies at birth or if developed in childhood.

A

Severe at birth, with little progression
Can be developed in childhood with rapid progression
-usually results in severe vision loss and nystagmus

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8
Q

Describe how delayed onset rod-cone dystrophies differ from early onset. Do they result in complete vision loss or nystagmus?

A

Symptoms develop late and progress more slowly

Rarely results in near complete vision loss or nystagmus

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9
Q

What kind of disease is lebers congenital amaurosis and what kind of mode of inheritance does it have? Is it common or rare?

A

Common form of early onset rod-cone dystropy

Autosomal recessive

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10
Q

What kind of vision is present since birth for those with lebers congenital amourosis? What else is present?

A

Very poor vision with roving nystagmus

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11
Q

What is the fundus like in lebers congenital amourosis?

A

May appear normal or may show abnormalities

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12
Q

Is ERG normal or abnormal with lebers congenital amourosis?

A

Abnormal

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13
Q

Is x-linked retinitis pigmentosa a common or uncommon form of retinitis pigmentosa? What about rod-cone dystrophy?

A

Common form of early onset rod-cone dystrophy, but not a common form of RP overall

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14
Q

Which gender is usually fully affected with x-linked retinitis pigmentosa? Explain.

A

Males usually fully affected

Females often have milder form (can be fully affected)

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15
Q

What is vision like in childhood with x-linked retinitis pigmentosa? What eventually happens?

A

Fairly good vision in childhood, but lose both peripheral and central vision rapidly

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16
Q

How many genes have been implicated in x-linked retinitis pigmentosa?

A

At least 6

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17
Q

What is the most common form of retinitis pigmentosa?

A

Autosomal recessive

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18
Q

List three classical features of retinitis pigmentosa.

A

Night blindness
Loss of peripheral vision
Intraretinal pigmentation
-bone spicule-like

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19
Q

Are the dominant or recessive forms of retinitis pigmentosa often more severe?

A

Recessive forms often more severe

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20
Q

How many genes are implicated in autosomal recessive retinitis pigmentosa?

A

At least 25

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21
Q

What is the second-most common form of retinitis pigmentosa?

A

Autosomal dominant

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22
Q

Does autosomal dominant retinitis pigmentosa have the classical features of retinitis pigmentosa?

A

Yes

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23
Q

Describe the severity, age of onset, and penetrance of autosomal dominant retinitis pigmentosa (2).

A

It varies widely depending on abnormal function gained and haploinsufficiency

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24
Q

Is it easy or difficult to predict causal gene from the observed phenotype in autosomal dominant retinitis pigmentosa?

A

Difficult

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25
Q

How many genes are implicated in autosomal dominant retinitis pigmentosa?

A

At least 18

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26
Q

Describe cone-rod dystrophies.

A

Family of progressive diseases in which cone dysfunction is more severe than rod dysfunction

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27
Q

What kind of vision loss is expected in cone-rod dystrophies?

A

Loss of central vision - central scotoma

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28
Q

What is seen on ERG with cone-rod dystrophies?

A

Cone-driven ERG responses affected

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29
Q

Is retinal damage typically seen with cone-rod dystrophies?

A

Yes

-atrophy and/or pigmentary changes

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30
Q

True or false
Cone dystrophies are allelic to cone-rod dystrophies
Explain what this means.

A

True
Cone and cone-rod dystrophies
represent phenotypic variations of the same disease

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31
Q

True or false

Cone and cone-rod dystrophies do not cause light aversion.

A

False

They do

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32
Q

How many genes are implicated for the following cone and cone-rod dystrophies?
X-linked
Autosomal recessive
Autosomal dominant

A

X-linked - at least 1
Autosomal recessive - at least 13
Autosomal dominant - at least 13

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33
Q

What are vitreoretinal dystrophies?

A

Retinal disorders associated with vitreal degeneration

34
Q

What is one of the most common causes of macular disease in male children? Especially what ethnicity?

A

X-linked retinoschisis

-finnish

35
Q

What would yuo expect to see on an ERG with retinoschisis (2)?

A

Selective reduction in b-wave of DA-white ERG

-reduced b/a-wave ratio

36
Q

What does enhanced S-cone syndrome cause and what mode of inheritence? Does it cause vision loss? What about night vision and at what age? What happens to the other cones?

A

Gain in function of s-cones
Causes visual loss with night blindness from early age
Varying degree of L and G cone vision and retinal degeneration

37
Q

What happens to the retina with enhanced S-cone syndrome and what area?

A

Abnormally thick retina in annulus surrounding the fovea

38
Q

What is the severe form of enhanced S-cone syndrome called and what is it similar to?

A

Goldmann-favre vitreoretinal dystrophy

-similar to clumped pigmentary retinal degeneration

39
Q

What can enhanced S-cone syndrome mimic?

A

X-linked retinoschisis

40
Q

What would you expect to see on ERG with enhanced S-cone syndrome (2)?

A

Both DA white and LA white ERG responses are usually electronegative

41
Q

How many genes are implicated in enhanced S-cone syndrome?

A

1

42
Q

What mode of inheritence do the following have:
Sticker syndrome
Wagner syndrome

A

Both autosomal dominant

43
Q

What are exudative vitreoretinopathies (3)?

A

Predisposition to retinal exudates
Leaky angiography
Predisposition to seous retinal detachments

44
Q

Is it common or rare to lose all vision in retinitis pigmentosa?

A

Rare

45
Q

Describe retinitis pigmentosa and dark adaptation and night blindness.

A

Those with RP have difficulty with dark adaptation and night blindness during adolescence

46
Q

Describe the progression of vision loss over time with retinitis pigmentosa (3).

A

Lose mid-peripheral vision, then far peripheral vision in adulthood
Eventually tunnel vision
-reductions in central vision occur later

47
Q

Are the signs and symptoms of retinitis pigmentosa consistent or highly variable?

A

Highly variable

48
Q

What three things can you expect to see in advanced cases of retinitis pigmentosa?

A

Intraretinal bone spicule pigmentation in the midperiphery
Waxy pallor of the optic disc
Attenuated retinal blood vessels

49
Q

Why do bony spicule pigmentation occur where they do in retinitis pigmentosa?

A

In the midperiphery because this is the region of greatest rod density

50
Q

What five things may you see in early cases of retinitis pigmentosa?

A
Night blindness
Loss of peripheral vision
Difficulty with tasks requiring good VA
Myopia/astigmatism
Hearing loss
51
Q

Define nyctalopia.

A

Night blindness

52
Q

What is the progression of night blindness like in retinitis pigmentosa and when is it typically first noticed?

A

Often slow and insidious onset/progression

First noticed 2nd or 3rd decade

53
Q

What percentage of retinitis pigmentosa patients will develop cystoid macula oedema, if any?

A

10%

54
Q

What will most retinitis pigmentosa patients develop in adulthood?

A

Posterior subcapsular cataract

55
Q

Is hearing loss common or rare in retinitis pigmentosa patients?

A

Common

56
Q

List the nine components of assessing retinitis pigmentosa.

A
VA
Refraction
Visual fields
Colour vision
Dark adaptation
Slit lamp
Ophthalmoscopy
ERG
OCT
57
Q

What would you expect of VA when assessing retinitis pigmentosa? What about early cases?

A

Can remain normal

-can be lost early

58
Q

What is myopia with retinitis pigmentosa more indicative of? What about hypelopia?

A

Myopia greater than -2.00D - more likely to be X-linked

Hyperopia - more likely to be autosomal dominant

59
Q

What kind of visual field defects would you expect when assessing retinitis pigmentosa?

A

Mid-peripheral scotomas early, which expand outward and inward

60
Q

Describe the progression of visual field defects over time in retinitis pigmentosa towards the pole and towards the periphery.

A

Mid-peripheral scotomas early

  • central margin is steeper and progresses slowly
  • peripheral margin is flatter and progresses rapidly
61
Q

Are defects often symmetrical or asemmetrical in retinitis pigmentosa?

A

Symmetrical

62
Q

What may retinitis pigmentosa visual field defects mimic? What two things should it not be confused with?

A

Arcuate defect

-dont confuse with glaucoma or ONH drusen

63
Q

When should central field testing be done for retinitis pigmentosa cases, if at all?

A

Late stage

64
Q

What is expected of colour vision in retinitis pigmentosa? What may other abnormalities indicate?

A

Normal (early) or acquired tritanopia (late)

-other abnormalities may indicate cone or cone-rod dystrophy

65
Q

What may you find on slit lamp examination of a retinitis pigmentosa patient?

A

Posterior sub-capsular cataract

66
Q

What may commonly be seen in the vitreous humour of retinitis pigmentosa patients?

A

Cells

67
Q

Why should you do OCT for retinitis pigmentosa (2)?

A

Assess the status of the photoreceptor layer (ISe integtrity)
Identify presence/absence of CMO

68
Q

List 6 other syndromes that are differential diagnoses for retinitis pigmentosa.

A
Usher
Bardet-biedl
Alport
Cohen
Jeune
Cockayne
69
Q

List four conditions that mimic retinitis pigmentosa.

A

Syphillis
Measles
Trauma
Drug toxicities

70
Q

What drug toxicity can mimic retinitis pigmentosa?

A

Quinine/chloroquine

71
Q

List three conditions that cause RPE disruptions that are differential diagnoses for retinitis pigmentosa.

A

Old retinal detachment
Choroideremia
Gyrate atrophy

72
Q

What four referrals may cases of retinitis pigmentosa require?

A

Ohpthalmological examination
Electrodiagnosis (ERG)
Dark adaptationGenetic counselling

73
Q

What five baselines should be maintained for retinitis pigmentosa patients?

A
VA
Colour vision
Visual fields
Retinal photography
Dark adaptation
74
Q

List 5 vision rehabilitation options for retinitis pigmentosa patients.

A
Tinting
Night vision goggles
Wide angle mobility lamp
Field expanders
Hand-held/computer assisted magnifiers
75
Q

Which of the following treatment options are effective for retinitis pigmentosa:
Vitamin/minerals, vasodilators, tissue therapy with placental extract,
cortisone, cervical sympathectomy, injections of a hydrolysate of yeast ribonucleic acid
(RNA), ultrasound, transfer factor, dimethyl sulfoxide (DMSO), ozone, muscle
transplants, and subretinal injections of foetal retinal cells.

A

None of these have been proven

76
Q

What is the effect of vitamin A supplementation on retinitis pigmentosa ERG? What about VA and visual fields?

A

Slows decline in ERG amplitude

VA and visual fields not significantly affected

77
Q

List two risks of taking high dose vitamin A.

A
Hip fractures
Birth defects (not recommended for pregnant women)
78
Q

What is the effect of vitamin A supplementation on retinitis pigmentosa patients?

A

No clear benefit

79
Q

Does light exposure in retinitis pigmentosa speed up degeneration? Explain.

A

In animals yes

In humans, there was no effect

80
Q

List 4 possible future treatment options for retinitis pigmentosa.

A

Gene therapy
Nutritional/neuroprotective intervention
Transplantation (stem cells)
Implants