Genetics Flashcards
What can tuberous sclerosis present as?
Infantile seizures
Earliest cutaneous sign of tuberous sclerosis
Ash-leaf molecule (depigmented macules)
Tuberous sclerosis is autosomal dominant/recessive
Autosomal dominant but new mutations are common
Tumours of tuberous sclerosis
Periungal fibromas - around nails Facial angiofibromas Cortical tubers and/or calcification of the flax cerebri Hamartomas Angiomyolipomas Bone cysts
Skin signs of tuberous sclerosis
Ash-leaf molecule
Shagreen patches
Enamel pitting
What are shagreen patches?
Fibrous hamartomas in the skin
Hamartoma
Overgrowth of normal tissue
Where is the mutation in tuberous sclerosis?
TSC1 or TSC2 which code for tuberin and hamartin
What is epidermolysis bullosa?
A group of genetic skin fragility conditions
3 main types of epidermolysis bullosa
Simplex
Junctional
Dystrophic
Which part of the skin does simplex epidermolysis bullosa affect?
The dermis
Which part of the skin does junctional epidermolysis bullosa affect?
Dermo-epidermal junction
Which part of the skin does dystrophic junctional epidermolysis bullosa affect?
The dermis
What is haploinsufficiency disease mechanism?
Only one copy of the gene is working leading to decreased protein production
What does dominant negative mean?
The expression of abnormal protein interferes with normal protein
What does gain of function mean?
Mutant protein gains a new function, affecting all cell processes
What is complete loss of protein?
Autosomal recessive where 2 faulty copies of the gene produce no protein
How many cafe au lait macules suggest genetic disease?
> 5
Clinical features of neurofibromatosis type I
Cafe au lait macules and neurofibromas Axillary or inguinal freckling Optic glioma Plexiform neuroma 2 or more Lisch nodules Distinctive bony lesion
What are cafe au lait macules?
Birthmarks
