8: Genetics - tuberous sclerosis, epidermolysis bullosa, NF type 1 Flashcards
What is the biggest factor contributing towards your chance of having a mutation?
Age of the father
A patient presents with periungual fibromata and longitudinal ridging in their toenails.
What is a periungual fibroma?
What genetic condition do they have?
Small lesions found at the nail folds
Tuberous sclerosis
What is an early neuro sign that a person may have tuberous sclerosis?
Infantile seizures
What is the mode of inheritance for tuberous sclerosis?
Autosomal dominant
Can tuberous sclerosis develop spontaneously in an adult? If so, why?
Yes
Spontaneous mutation
Mutations in which genes are responsible for tuberous sclerosis?
TSC1
TSC2
What type of genes are TSC1 and TSC2?
Tumour suppressor genes
Which specific proteins do TSC1 and TSC2 code for?
TSC1 - hamartin
TSC2 - tuberin
What is the earliest cutaneous sign of tuberous sclerosis?
Ash-leaf macules
Which piece of equipment can be used to better visualise ash-leaf macules?
Wood’s lamp
What are ash-leaf macules?
Depigmented macules which look like trees
What are facial angiofibromas?
Brown lesions on the face
Cortical tubers are another sign of tuberous sclerosis. What can they cause?
Seizures
What are hamartomas?
Where can they be found in tuberous sclerosis?
Benign growth malformations which resemble neoplasms
Heart, lungs, kidneys
What happens to the tooth enamel in tuberous sclerosis?
Pitting
What are Shagreen patches?
Where are they found?
Connective tissue lesions which look like orange peels
Lower back
Name five signs of tuberous sclerosis.
Seizures
Ash-leaf macules
Periungual fibromas
Facial angiofibromas
Cortical tubers
Hamartomas
Shagreen’s patches
Pitting of tooth enamel
Bone cysts
Autosomal dominant conditions are seen in (all / some) generations.
all generations
If a parent is affected by an autosomal dominant condition, what are the chances of their child inheriting it?
50%
What two characteristics of autosomal dominant conditions are variable?
Expressivity (whether it is severe or not)
Penetrance (whether it presents or not)
Are males and females equally likely to inherit an autosomal dominant condition?
Yes
During transcription, (introns / exons) are removed from DNA.
introns