Lecture 3: Dominant mutations File Flashcards
Always think of it from the mutant alleles point of view
e.g. mutant allele is recessive to wild type, NOT wild type is dominant to mutant allele
what does loss-of-function mean ?
When recessive alleles code for a protein that works less than the wild type or does not function at all
most recessive mutations are_______?
most dominant mutations are _________?
most recessive mutations are loss-of-function
most dominant mutations are gain-of-function
Why are most mutations recessive (>95%)?
Its easier to damage something, than make it work better/differently
What is achondroplasia?
Autosomal dominant mutation, most common form of dwarfism
How does achondroplasia occur ?
Point mutation in fibroblast growth factor receptor 3 (FGFR3), a transmembrane protein kinase.
What is FGFR3’s job and how is it mutated in achondroplasia?
FGFR3 inhibits/slows growth.
Mutant receptor is locked in a more active state, hence limbs fail to grow normally
Where are mutations for achondroplasia usually generated ?
Parents germ line
Sufferers of anchondroplasia gain a ____ function
Sufferers of anchondroplasia gain a normal function
Sufferers of huntingtons disease gain an _____function
Sufferers of huntingtons disease gain an abnormal function
What is huntingtons disease?
Progressive neurodegenaration, autosomal dominant mutation
What is the gene and protein affected in HD?
Gene = HDD1 Protein = Huntingtin
Does HD skip generations ? why?
No, carriers will have the phenotype as it is dominant
Is HD sex linked ? why?
No. It is an AUTOSOMAL dominant mutation
Whats the difference between a normal brain and a HD patients brain ?
HD patient brain has less overall mass, and more holes/gaps
