Mrs Jones (2) - Risk of Disease Transmission Flashcards
Give examples of a monogenic disease
Huntingtons, CF, haemophilia
What are monogenic disease characteristics
clear inheritance, no environment cause, rare
Give examples of complex disorders
T2 diabetes, schizophrenia, chron’s
What are complex disease characteristics
no clear inheritance, environmental effect, common
define mutation
heritable change in DNA sequence, causes monogenic disease
What is a polymorphism?
a mutation that is present in more than 1% of the population
Name mutation types
missense, nonsense, insertion, deletion
What is a missense mutation?
incorrect nucleotide = incorrect A.A
What is a nonsense mutation?
incorrect A.A result in STOP codon, shortened protein
Why is a detailed history taken?
identify genetic disease, inheritance pattern, aid diagnosis, assist management, identify risk
Huntington’s disease characteristics
Autosomal dominant
CAG triplet repeat
motor, cognitive and psychiatric dysfunction
35-44 yrs onset
survival is 15-18yrs after onset
no cure
onset age decreases and severity increases down the generations
CF characteristics
Autosomal recessive
thick mucus, breathing problems, infections
pancreas blockages and digestive enzymes affected
treated with daily enzymes and physiotherapy
Haemophilia characteristics
X-linked recessive males affected blood clotting disorder bruise easy, bleed longer types A and B clotting factor injections
define incomplete penetrance
symptoms not always present in individual with disorder causing mutation
define variable expressivity
disease severity varies between individuals with same mutation
define epistasis
interaction between disease mutation and other modifier genes affects phenotype
define phenocopy
same disease but with different underlying cause
compare dominant, co-dominant and recessive protein production and treatment
dominant - presence of toxic protein that masks effect of normal copy, treatment neutralises effects or switches off mutant gene
co-dominant - effects of both mutated and normal gene in phenotype, treatment same as dominant
recessive - absence of functional protein, treatment restore activity of missing protein by replacing protein
