Hereditary Retinal dystrophies Flashcards
(149 cards)
Nwhat is OMIM?
the online mendelian Inheritance in Man (website)
how many genetic disorders affect the retina and choroid?
nearly 750 according to OMIM
name 2 websites to look for genetic information on retinal diseases?
OMIM and RetNet
most retinal hereditary disease are unilateral or bilateral?
most are bilateral if unilateral please suspects -infections or inflammatory
name a reversible cause of retinal degeneration?
vitamin A
what are the mendelian patterns of inheritance?
AD AR X-linked recessive x-linked dominant mitochondrial
if a patient has a retinal degeneration but no family history …
the patient may have a ne novo mutation or the family members may have a mild form of disease making them asymptoatic
within a same gene there could be different mutations
and each of these can give a different phenotypes for example mutation in the RDS/peripherin can cause: - RP - cone-rod dystrophy - pattern dystrophy mutations in rhodopsin gene cause: -CSNB -RP mutations in CRX (cone-rod homeobox containing gene) can cause: -LCA -cone-rod dystrophy mutaions in Stargardt gene cause: -stargardt disease -severe progressive cone-rod dystrophy -RP
what percentage of patients with the Usher sd mutation have usher without hearing loss?
5%
tell me about Autosomal dominant inheritance
the disease presents in each generation there is 50% chance of passing the disease to offspring no sex predilection
tell me about autosomal recessive inheritance
the affected individual passes the disease to 25% of offspring not every generation affected no sex predilection
what is the inheritance in Stargardts disease?
most common is AR ( stARgardts) with most common gene ABCA4 BUT… it can also be AD with the gene ELOV4
what is the inheritance in RP?
all forms… AR, AD, x-linked to remember it is also like stargardts in a way because th emost common inheritance is AR (70%) then AD (15%) ad x-linked (15%) the most common genes for RP are: if: AR (ABCA4 and Ush2A AD (30% by rhodopsin) x-linked (80% RPGR - most severe so remember RP grrrrrr angry) and RP2 10%
most common genes in RP
the most common genes for RP are: if: AR (ABCA4 and Ush2A AD (30% by rhodopsin) x-linked (80% RPGR - most severe so remember RP grrrrrr angry) and RP2 10%
RPE functions
Absorption -of scattered light -of energy and heat Phagocytosis - of photoreceptor outer segment discs TRansport - of photreceptor waste products to choroid - of nutrients fro choroid to photoreceptors Blood retina barrier Retinal adhesion
so doctor….. why do I need the genetic testing?
well… if we know the precise diagnosis… - we can give you a more definitive prognosis - we can rule out syndromes or systemic diseases (important in LCA) - it will give you peace of mind - give you better genetic counseling - identify if we need to test your family - keep you posted on clinical trials MY JOB IS TO ORDER the most specific gene testing so you don’t waste money ALSO I will give you a copy of the report.
PPRCA Pigmented paravenous retinochoroidal atrophy
rare disease unknown etiology PIGMENT accumulation along the retinal vessels WITH sectors of NORMAL retina in between. usually, vision is normal First described on 1937 no genes found more common in males involves the RPE and choroid
what is the name of the contact lens electrode used for ERG?
Burian-Allen
How many genetic disorders affect the eye?
750
How many retina degenerations with an identified gene are listed in RetNet?
Over 200
If disease is unilateral what should you think?
Infection inflammation cancer
Depending on where the mutation lies on the gene…
The phenotype will be different
Different mutations in the RDS/peripherin can cause…
Cone-rod dystrophy RP Pattern dystrophy
Different mutations in the rhodopsin gene can cause
RP CSNB