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Dermatology Week 2 2017/18 > 8: Genetics - tuberous sclerosis, epidermolysis bullosa, NF type 1 > Flashcards

8: Genetics - tuberous sclerosis, epidermolysis bullosa, NF type 1 Flashcards

1
Q

What is the biggest factor contributing towards your chance of having a mutation?

A

Age of the father

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2
Q

A patient presents with periungual fibromata and longitudinal ridging in their toenails.

What is a periungual fibroma?

What genetic condition do they have?

A

Small lesions found at the nail folds

Tuberous sclerosis

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3
Q

What is an early neuro sign that a person may have tuberous sclerosis?

A

Infantile seizures

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4
Q

What is the mode of inheritance for tuberous sclerosis?

A

Autosomal dominant

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5
Q

Can tuberous sclerosis develop spontaneously in an adult? If so, why?

A

Yes

Spontaneous mutation

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6
Q

Mutations in which genes are responsible for tuberous sclerosis?

A

TSC1

TSC2

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7
Q

What type of genes are TSC1 and TSC2?

A

Tumour suppressor genes

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8
Q

Which specific proteins do TSC1 and TSC2 code for?

A

TSC1 - hamartin

TSC2 - tuberin

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9
Q

What is the earliest cutaneous sign of tuberous sclerosis?

A

Ash-leaf macules

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10
Q

Which piece of equipment can be used to better visualise ash-leaf macules?

A

Wood’s lamp

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11
Q

What are ash-leaf macules?

A

Depigmented macules which look like trees

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12
Q

What are facial angiofibromas?

A

Brown lesions on the face

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13
Q

Cortical tubers are another sign of tuberous sclerosis. What can they cause?

A

Seizures

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14
Q

What are hamartomas?

Where can they be found in tuberous sclerosis?

A

Benign growth malformations which resemble neoplasms

Heart, lungs, kidneys

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15
Q

What happens to the tooth enamel in tuberous sclerosis?

A

Pitting

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16
Q

What are Shagreen patches?

Where are they found?

A

Connective tissue lesions which look like orange peels

Lower back

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17
Q

Name five signs of tuberous sclerosis.

A

Seizures

Ash-leaf macules

Periungual fibromas

Facial angiofibromas

Cortical tubers

Hamartomas

Shagreen’s patches

Pitting of tooth enamel

Bone cysts

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18
Q

Autosomal dominant conditions are seen in (all / some) generations.

A

all generations

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19
Q

If a parent is affected by an autosomal dominant condition, what are the chances of their child inheriting it?

A

50%

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20
Q

What two characteristics of autosomal dominant conditions are variable?

A

Expressivity (whether it is severe or not)

Penetrance (whether it presents or not)

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21
Q

Are males and females equally likely to inherit an autosomal dominant condition?

A

Yes

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22
Q

During transcription, (introns / exons) are removed from DNA.

A

introns

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23
Q

(Introns / exons) are vital for RNA and protein expression.

A

Exons

24
Q

Which experimental drugs may be used to treat tuberous sclerosis?

A

mTOR inhibitors

25
Q

Tuberous sclerosis shows genetic heterogeneity. What does that mean?

A

The mutation can be in either TSC1 or TSC2 and the disease will still present itself

26
Q

Some people have the mutation but don’t show features of the disease at all - its ___ is variable.

Tuberous sclerosis has varying severity in different people - its ___ is variable.

A

penetrance

expressivity

27
Q

Is tuberous sclerosis a:

Mendelian disorder (with high penetrance but low frequency)

or a Multifactorial disorder (with low penetrance but high frequency)?

A

Mendelian disorder

28
Q

What is epidermolysis bullosa?

A

A group of genetic skin fragility conditions

Causes skin loss and blistering on gentle handling of patient

29
Q

Is epidermolysis bullosa autosomal dominant or recessive?

A

All of the above

can also be acquired via a new mutation

30
Q

What is the presentation of epidermolysis bullosa?

A

Widespread blistering and skin shedding on slight handling of skin

31
Q

What are the three types of epidermolysis bullosa, and which layers of the skin are affected?

A

Simplex - epidermis only

Junctional - dermo-epidermal junction

Dystrophic - all the way to the dermis

32
Q

How many faulty genes are involved in epidermolysis bullosa?

A

> 10 genes (probably 20 now)

33
Q

The genes for which protein families are faulty in epidermolysis bullosa?

A

Keratin

Collagen

Integrins

34
Q

The faulty genes in epidermolysis bullosa are usually responsible for skin ____ and ___.

A

structure and adhesion

35
Q

What is epidermolysis bullosa aquisita?

A

Rare autoimmune condition similar to EB

36
Q

What is haploinsufficiency?

A

Mutant gene doesn’t produce any protein, meaning only half as much protein is produced

37
Q

What is dominant negative disease expression?

A

Mutant gene causes production of abnormal protein, which interferes with normal protein

38
Q

A mutation in a gene for protein can cause that protein to gain new ___.

Which disease type is this important in?

A

function

Cancer

39
Q

If a disease is autosomal recessive, how much protein will be produced?

A

None

oops

40
Q

How many generations are affected by autosomal recessive conditions?

A

Usually only one

41
Q

If a parent has an autosomal recessive condition, what is the chance of their child inheriting it?

A

25%

42
Q

The chance of children inheriting autosomal recessive conditions is increased in families which are ___.

A

consanguineous

i.e inbreeding

43
Q

What is the name given to round, flat coffee-coloured marks on the skin which are asymptomatic?

A

Cafe au lait macules

44
Q

Cafe au lait macules are found on 10-20% of normal people. More than how many suggests that a person has a genetic disease?

A

More than 5

45
Q

What is a neurofibroma?

A

Benign nerve sheath tumour found on the SKIN - brown, soft, papular

46
Q

If a patient presents with more than 5 cafe au lait macules and neurofibromas, which genetic skin condition do they have?

A

Neurofibromatosis type 1

47
Q

What is the mode of inheritance of neurofibromatosis type I?

A

Autosomal dominant

48
Q

Apart from Cafe au lait macules and neurofibromas, what are some other signs of neurofibromatosis type I?

A

Axillary / inguinal freckling

Optic gliomas (eye tumours)

Bony lesions

49
Q

Which drugs may be used to treat neurofibromatosis type I in the future?

A

MEK inhibitors

50
Q

Most diseases (are / aren’t) caused by one gene.

A

aren’t

51
Q

Which skin disease, causing itchy skin and difficulty sleeping in infants, also has genetic contributing factors?

A

Atopic eczema

52
Q

A loss-of-function mutation in which gene is thought to cause atopic eczema?

A

Filaggrin gene

53
Q

Filaggrin mutations cause which disease?

A

Ichthyosis vulgaris

dead skin cells don’t shed, causing dry, itchy skin

54
Q

What is filaggrin an abbreviation for?

A

Filament aggregating protein

55
Q

The dark purple colour of which epidermal layer is lost in ichthyosis vulgaris?

A

Granular layer

56
Q

Mutations in the filaggrin gene increase your risk of which atopic conditions?

A

Eczema

Asthma

Hayfever

Peanut allergy

Dermatology Week 2 2017/18 (8 decks)

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