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Dermatology > Genetics - Cases and Mechanisms > Flashcards

Genetics - Cases and Mechanisms Flashcards

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Dermatology Board Prep flashcards
1
Q

what is precision medicine?

A

using some form of testing to identify a subgroup of patients who respond to a treatment
can involve genetic testing

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2
Q

what is precision medicine used in right now?

A

cancer

some diseases

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3
Q

what is the benefit of precision medicine?

A

can test whether treatment will be effective in people so people will get effective treatment instead of giving everyone the same and it not working for some

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4
Q

what are periungual fibromata? are they always pathological?

A

fibrous, bulbous overgrowths at cuticle of nail

one can be normal but many is pathological

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5
Q

what is periungual fibromata diagnostic of?

A

tuberous sclerosis

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6
Q

what is tuberous sclerosis?

A

autosomal dominant genodermatoses

causes infantile seizures and can produce ash leaf macules in skin (depigmented)

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7
Q

how can ash leaf macules be seen on pale skin?

A

woods lamp

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8
Q

what are the signs of tuberous sclerosis?

A 
periungual fibromas
facial angiofibromas
cortical tumours - epilepsy
hamartomas - angiomyolipomas
bone cysts
shagreen patches
enamel pitting
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9
Q

what are angiofibromas?

A

erythematous papules
can be misdiagnosed as acne, but doesn’t form comodones
begin in first year of life and progress through life

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10
Q

what causes tuberous sclerosis?

A

autosomal dominant mutation in either 9q34 or 16p13.3 AFFECTING TSC1 and TSC2 genes (codes for tuberin and hamartin - tumour regulating genes)

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11
Q

is tuberous sclerosis always inherited?

A

not always

can be a spontaneous mutation

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12
Q

are new mutations common?

A

yes
can have around 120 new mutations that aren’t present in parents
depends on how old father is (older = more mutations)

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13
Q

% chance of being affected by autosomal dominant mutation if parent is affected?

A

50%

but disease not always shown

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14
Q

how does a mutation cause a problem?

A

affects central dogma

i.e can effect protein synthesis

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15
Q

what are the types of mutation?

A

missence - single nucleotide mutation
deletion (in frame) - deletion of a codon
Premature stop - premature stop codon
deletion (frameshift) - deletion of a number of nucleotides not divisible by 3

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16
Q

give an example of a treatment created through precision medicine?

A

rapamycin

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17
Q

what type of mutation does precision medicine work best for?

A

high penetrance disorders

18
Q

how does precision medicine work?

A

identify genes for a disease which tells you the pathway

pathways can then be targeted for treatments

19
Q

what is genetic heterogeneity?

A

the causative mutation in a genetic disease can be in one of two genes

20
Q

skin of baby blistered at birth which then progresses to extensive skin loss occurring with any movement/handling of baby?

A

EB - Epidermolysis Bullosa

21
Q

what is EB?

A

group of genetic fragility conditions

variable severity of blistering and skin loss

22
Q

what is EB?

A

group of genetic skin fragility conditions

variable severity of blistering and skin loss

23
Q

simplex type?

A

split in epidermis, surface of blister is upper epidermis

almost normal life, just blister very easily

24
Q

simplex type EB?

A

split in epidermis, surface of blister is upper epidermis

almost normal life, just blister very easily

25
Q

junctional type EB?

A

split is at dermo-epidermal junction

heals with scarring

26
Q

dystrophic type EB?

A

split is in the dermis

cant heal, causes extensive scarring (mitten deformity)

27
Q

types of keratin?

A

type 1 and type 2 which bind to form a dimer > tetramer giving structural integrity

28
Q

what are the types of keratin and what do they do?

A

type 1 and type 2 which bind to form a dimer > 2 dimers form a tetramer giving structural integrity

29
Q

through what 4 mechanisms can a mutation cause a disease?

A

good gene not producing enough (e.g protein) so deficiency causes disease
= haploinsufficiency
OR
mutation makes abnormal protein which stops the normal protein working
= dominant negative (more severe effect)
mutant protein gains new function affecting cell process
= gain of function
2 faulty copies of gene produce no protein
= complete loss of protein (autosomal recessive)

30
Q

how can mutations arise in offspring when the parents don’t have the mutation?

A

new mutation occurs in one parents gametes

one parent is mosaic so has some copies of mutation but not all

31
Q

asymptomatic coffee coloured flat marks?

A

café au lait macules

>5 indicates neurofibromatosis type 1

32
Q

clinical signs of neurofibromatosis?

A 
café au lait macules
neurofibromas (soft and squishy tumours)
axillary/inguinal freckles
plexiform neuroma
optic gliomas (eye tumours)
Lisch nodules
Bony lesions
33
Q

is neurofibromatosis autosomal dominant?

A 
quite often (50-60%)
or can be a new mutation
34
Q

what does neurofibromine do?

A

involved in cell growth

35
Q

red, rough patches of skin at 2 weeks old which becomes more itchy and broken?

A

atopic eczema

36
Q

which components of atopic eczema do genetic factors effect?

A

skin barrier effect (filaggrin) and immunology (interleukin 4 and 13)

37
Q

what does a filaggrin mutation cause?

A

hyperlinear palms (wrinkly)
dry skin
more severe ichthygosis vulgaris effects if both copied affected
has a role in atopic diseases

38
Q

what does a filaggrin mutation cause?

A

hyperlinear palms (wrinkly)
dry skin
more severe ichthygosis vulgaris effects if both copied affected
has a role in atopic diseases

39
Q

what can a filaggrin mutation predispose to?

A 
atopy
hayfever
asthma
eczema
food allergy (esp. peanuts)
due to leakiness caused
40
Q

are most human diseases monomeric?

A

no

most are comlex - many genes interacting with many environments

Dermatology (38 decks)

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