BS - Genetics of Eye Diseases - Week 3 Flashcards
Do AMD or glaucoma have a genetic component?
Yes, they both do.
Name the 6 mendelian inheritance patterns.
Autosomal recessive Autosomal dominant X-linked recessive X-linked dominant Codominant Mitochondrial
Name 2 common genetic diseases in school-aged children.
Strabismus
Congenital Nystagmus
Is the prevalence of myopia very high, medium, or low in the general population?
Very high in the general population
What is the prevalence of myopia like in Aisan populations compared to others?
Significantly higher, up to 90%
What is the likely inheritance pattern of myopia (2)?
It can be mendelian, but more often inherited as a complex trait.
What percentage of congenital cataracts have a genetic cause?
50%
Mutations of genes controlling what mechanisms lead to cataracts (4)?
Lens development (PAX6) Lens crystallins (CRY) Gap junctions (Cx43) Aquaporins
What is the 2nd leading cause of congenital vision loss?
Optic nerve hypoplasia
What are the risk factors for optic nerve hypoplasia (7)? What percentage of cases do not have these risk factors?
Preterm birth Alcohol Quinine (malaria) Phenytoin (siezures/cardiac problems) Maternal diabetes Congenital cytomegalovirus infection LSD consumption 70% do not have the above risk factors
What are three symptoms of optic nerve atrophy?
Vision loss
Poorer colour vision
Nerve lost tissue, pale
Name the two forms of optic nerve atrophy, and their inheritance pattern.
Optic atrophy 1 - autosomal dominant
Lebers hereditary optic atrophy - mutations in mitochondrial DNA
What are the inheritance patterns most colour vision deficiency conditions?
X-linked recessive
Name one of the most common retinal degeneration conditions.
Retinitis pigmentosa
Define retinitis pigmentosa.
A group of many forms of inherited retinal dystrophy, or degeneration.
Mutations to proteins in what 7 mechanisms would result in retinitis pigmentosa?
Phototransduction cascade Vitamin A metabolism Cell-cell/synaptic interaction Intracellular protein trafficking Cilia maintenance pH regulation Phagocytosis
What is a symptom of mutations to RPE65, what is this condition called, and what is its inheritance pattern? When is it typically diagnosed?
Blindness with autosomal recessive inheritance
Typically diagnosed within the first few years of life
Also known as leber congenital amaurosis
Mutations to how many genes can cause leber congenital amaurosis?
> 12 genes
What percentage of RPE65 mutations does leber congenital amaurosis account for?
6%
Name 5 means of subjectively assessing retinal function in retinitis pigmentosa.
Visual acuity Contrast sensitivity Flicker sensitivity Dark adaptation Visual fields
Name 2 means of objectively assessing retinal function in retinitis pigmentosa.
Pupil response
Electrophysiology
What is the EOG and what is it modified by?
The ocular resting potential
It is modified by derivatives of retinol acting on potassium channels in the RPE
Name 5 conditions that alter the EOG, and name what specifically they alter, define how its obtained, and the normal value.
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
What does the arden ratio represent?
The maximal K+ buffering capacity of the RPE - RPE function.
