Autosomal dominant Flashcards
Achondroplasia
inheritance
autosomal dominant
Achondroplasia
incidence
1/15,000-40,000
Achondroplasia
mutation rate?
80%
Achondroplasia
penetrance?
100%
Achnodroplasia
Clinical manifestations
Short
Rhizomelic limb shortening (proximal shortening)
short fingers
genu varum (bow legs)
large head / frontal bossing
midfacial retrusion
small foramen magnum / craniocervical instability
Achondroplasia
Mutated gene?
FGFR3
Fibroblast growth factor receptor 3
What does FGFR3 do?
Regulates bone growth by limiting the formation of bone from cartilage
FGF43 locus?
4p16.3 nucleotide 1138
Achondroplasia mutation?
nucleotide 1138 missense
1138G>A
amino acid substitution
Gly380Arg
Achondroplasia mutation consequence
Mutation increases the activity of the protein, interfering with skeletal development
What is special about the achondroplasia mutation 1138
The 1138 of FGFR3 has the highest known mutation rate in man
Men and de novo autosomal dominant conditions?
Men over the age of 40 are noted to have hgiher rate of children with de-novo autosomal dominant conditions - i.e. Achondroplasia
Paternal age effect
old dudes yield autosomal dominant mutated sperm
4 syndromes associated with paternal age effect
Achondroplasia
Apert syndrome
Crouzon syndrome
Pfeiffer syndrome
Retinoblastoma
what is it?
autosomal dominant condition
causes malignant tumor of retina
retinoblastoma incidence
1/15,000
retinoblastoma gene?
RB1 gene on chromsome 13
Retinoblastoma gene product role?
Retinoblastoma associated protein regulates the cell cycle
Retinoblastoma penetrance?
90%
Notable clinical finding in retinoblastoma?
no reflection of red retina - looks white
Neurofibromatosis Type 1 (NF1)
inheritance
frequency
mutation rate
autosomal dominant
1/3000
50% new mutation
NF-1
expressivity?
variable
NF-1 Diagnostic criteria
2 or more of the following
6 or more cafe au lait 2 or more neurofibromas 1 plexiform neurofibroma freckling in axillary or inguinal area optic glioma 2 or more Lisch nodules distinctive osseous lesions affected first degree relative
NF1 mutation?
NF1 gene
NF1 gene is what?
Neurofibromin - tumor suppressor gene
NF1 locus
17q11.2
NF1 type of mutation
loss of function
NF1 mutation?
over 1000 mutations have been described