Genetics in Dermatology Flashcards
widespread blistering and loss of skin in a newborn that is worsening?
epidermolysis bullosa
how many generations are affected in autosomal dominant inheritance?
all
what happens in the dominant-negative disease mechanism
abnormal protein stops normal protein working
what is the risk of an infected child if the parent is affected in autosomal dominant inheritance?
50%
clinical signs of neurofibromatosis type 1?
cafe au lait macules
neurofibromas
freckling of axilla/groin
optic glioma
what is the result of haploinsufficiency?
get half as much functioning protein
how many generations affected in autosomal recessive inheritance
often only 1
2 types of ridging commonly seen in the nails
longitudinal
transverse
what happens to a protein encoded by autosomal recessive genes?
no protein produced
3 main types of epidermolysis bullosa?
simplex (in epi)
junctional (DEJ)
dystrophic (dermis)
what do TSC1 and 2 genes normally code for?
TSC1 = Hamartin TSC2= Tuberin
what characteristics does a mendelian disorder have?
rare but very penetrable so you will get a strong phenotype
where do the mutations occur in tuberous sclerosis?
TSC1 and TSC2
what is haploinsufficiency?
only 1 gene working rather than 2
what aspect of the faulty tuberous sclerosis pathway can be inhibited to treat the disease?
inhibiting mTOR gene
what form of inheritance does tuberous sclerosis take
autosomal dominant
what is a hamartoma?
overgrowth of normal tissue
is TS mendelian or common?
mendelian
systemic symptoms of tuberous sclerosis
facial angiofibromas seizures/epilepsy hamartomas bone cysts enamel pitting shagreen patches (++ connective tissue)
common cytokines that play a big part in atopic eczema?
IL-4, IL-13
what happens when filaggrin is mutated?
ichthyosis vulgaris (fish scales), atopic disease risk +++
how many de novo mutations do children have?
120 mutations
common nail presentation of tuberous sclerosis
periungual fibromas and longitudinal ridging of nails
what are ash leaf macules and what condition are they common in?
depigmented macules on body
what causes epidermolysis bullosa?
acquired autoimmune condition affecting over 10 genes involved in skin structure and adhesion
what is a genodermatosis?
inherited skin condition
% risk of child getting the disease if it’s autosomal recessive?
25%
what is the driving force behind mendelian disorders?
mutations
what is the driving force behind common disorders?
SNPs
CNVs
Mutations
