Mrs Jones (2) - Risk of Disease Transmission

Question 1

Give examples of a monogenic disease

Answer 1

Huntingtons, CF, haemophilia

Question 2

What are monogenic disease characteristics

Answer 2

clear inheritance, no environment cause, rare

Question 3

Give examples of complex disorders

Answer 3

T2 diabetes, schizophrenia, chron’s

Question 4

What are complex disease characteristics

Answer 4

no clear inheritance, environmental effect, common

Question 5

define mutation

Answer 5

heritable change in DNA sequence, causes monogenic disease

Question 6

What is a polymorphism?

Answer 6

a mutation that is present in more than 1% of the population

Question 7

Name mutation types

Answer 7

missense, nonsense, insertion, deletion

Question 8

What is a missense mutation?

Answer 8

incorrect nucleotide = incorrect A.A

Question 9

What is a nonsense mutation?

Answer 9

incorrect A.A result in STOP codon, shortened protein

Question 10

Why is a detailed history taken?

Answer 10

identify genetic disease, inheritance pattern, aid diagnosis, assist management, identify risk

Question 11

Huntington’s disease characteristics

Answer 11

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

Question 12

CF characteristics

Answer 12

Autosomal recessive
thick mucus, breathing problems, infections
pancreas blockages and digestive enzymes affected
treated with daily enzymes and physiotherapy

Question 13

Haemophilia characteristics

Answer 13

X-linked recessive
males affected
blood clotting disorder
bruise easy, bleed longer
types A and B
clotting factor injections

Question 14

define incomplete penetrance

Answer 14

symptoms not always present in individual with disorder causing mutation

Question 15

define variable expressivity

Answer 15

disease severity varies between individuals with same mutation

Question 16

define epistasis

Answer 16

interaction between disease mutation and other modifier genes affects phenotype

Question 17

define phenocopy

Answer 17

same disease but with different underlying cause

Question 18

compare dominant, co-dominant and recessive protein production and treatment

Answer 18

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