Genetic disorders

Question 1

is tuberous sclerosis a mendelian disorder and what inheritance pattern does it follow

Answer 1

yes - it has high penetrance, low frequency

autosomal dominant

Question 2

which disorder may present with infantile seizures

Answer 2

tuberous sclerosis

Question 3

what is the earliest cutaneous sign of tuberous sclerosis

Answer 3

ash leaf macules (a depigmented macule)

Question 4

what tumours can tuberous sclerosis cause

Answer 4

1. periungual fibromas - tumours around nails
2. facial angiofibromas
3. hamartomas - resembles a neoplasm in tissue of origin
4. bone cysts

Question 5

what are shagreen patches and what are they associated with

Answer 5

areas of thick, leathery skin associated with tuberous sclerosis

Question 6

what 2 genes are affected in tuberous sclerosis and what does this cause

Answer 6

tubers and hamartin genes

they are both tumour regulator genes in the same pathway -
if either one is effected, the clinical presentation will be the same

Question 7

what are epidermolysis bullosa

Answer 7

a group of genetic skin fragility symptoms.

there are 3 main types

Question 8

what are the 3 main types of epidermolysis bullosa

Answer 8

1. simplex - occurs anywhere in epidermis
2. junctional - occurs at DEJ
3. dystrophic - occurs in dermis

Question 9

what disease is characterised by cafe au lait spots and axillary freckling

Answer 9

neurofibromatosis type 1

Question 10

in NFB type 1, what does >5 cafe au lait spots suggest

Answer 10

genetic disease

Question 11

what genetic disease is associated with benign and malignant nervous system tumours and optic gliomas

Answer 11

NFB type 1

Question 12

what effect will an optic glioma have on sight

Answer 12

it is a slow growing tumour that grows around the optic nerve
it compresses the optic nerve and causes gradual vision loss

Question 13

what’s the difference between cafe au lait spots and ash leãf macules

Answer 13

cafe au lait = hypER pigmented

ash leaf = hyPO pigmented