Genetics & Human Disease

Question 1

Each person is estimated to carry how many deleterious genes?

Answer 1

5-8

Question 2

Define Pleiotropism

Answer 2

A mutation in a single gene can lead to many effects

CF

Question 3

Define Genetic Heterogeneity

Answer 3

Mutations at several loci may produce the same trait

Diabetes, PKU

Question 4

Define Autosomal Dominant

Answer 4

Only need 1 parent to carry defective gene

Question 5

Define Autosomal Recessive

Answer 5

Both parents must carry defective gene

Question 6

Two Austosomal Dominant diseases?

Answer 6

Huntington’s disease

Familial hypercholesterolemia

Question 7

Define Huntington’s disease

Answer 7

Triplet repeat on chromosome 4

Dysfunctional protein builds up leading to toxicity at the GABA neurons

Question 8

Define Familial hypercholesterolemia

Answer 8

Defective LDL receptor –> inability to bind LDL and transport to liver

Question 9

Three Autosomal Recessive Disease

Answer 9

PKU
CF
Sickle cell anemia

Question 10

Define PKU

Answer 10

Defective phenylalanine hydroxylase –> build up in the CNS leading to mental retardation

Question 11

Define CF

Answer 11

Defective chloride ion channel –> thickened mucus secretion

Question 12

Define Sickle Cell Anemia

Answer 12

Defective hemoglobin which precipitates at low O2 tension

Question 13

Who is most effect by X-linked disease and why?

Answer 13

Males

They only have only one X (always from the father)

Question 14

Three X-Linked Recessive Diseases

Answer 14

Hemophilia A&B
G6PD deficiency
Diabetes insipidus

Question 15

Define Hemophilia A&B

Answer 15

Defect in clotting factors (8&9) –> prolonged bleeding

Question 16

Define G6PD deficiency

Answer 16

Most common enzyme defect

RBC are unable to repair

Question 17

Define Diabetes insipidus

Answer 17

Mutation in AVPR2 gene –> defective vasopressin receptor

Question 18

Majority of disease are?

Answer 18

Polygenic: different places for a mutation to occur

Question 19

Define Non-disjunction

Answer 19

Failure to separate

Question 20

Example of Non-disjunction

Answer 20

If you have non-disjunction in meiosis II then you could have one cell with two copies of chromosomes 21, then when it is fertilized there will be another making 3 copies of chromosomes 21

Question 21

Why do genetic diseases exist?

Answer 21

• We are living longer now

- Mutations may protect us from other disease

Question 22

Define Positive Selection

Answer 22

Heritable mutation which confers a survival advantage

Question 23

Examples of Positive Selection

Answer 23

Alcohol tolerance

Lactose tolerance

Question 24

How is Sickle Cell Anemia a beneficial mutation?

Answer 24

Heterozygotes protected from malaria

Question 25

How is CF a beneficial mutation?

Answer 25

Protects against typhoid

Question 26

How is Tay Sachs a beneficial mutation?

Answer 26

Protects against TB

Question 27

How is Type AB blood a beneficial mutation?

Answer 27

Highly resistant to chlorea

Question 28

Development of disease examples?

Answer 28

Multiple sclerosis, asthma

Question 29

Development of drug complications examples?

Answer 29

Factor V Leden and OCP's

Question 30

Define Multiple Sclerosis

Answer 30

Incidence is higher in countries far from the equator (US, Canada, N. Europe) - Both gene and environment

Question 31

What is the most common CV event in young women?

Answer 31

Venous Thrombosis

Question 32

How does Venous Thrombosis manifest?

Answer 32

Thrombosis of deep leg veins or PE

Question 33

Venous thrombosis interact with?

Answer 33

Oral contraceptives (estrogen) and the highest risk is in the first year of exposure

Question 34

Define Factor V Leiden Mutation

Answer 34

Position 506 Arginine is replaced with glutamine --> at the cleavage site so it cannot be cleaved leading to no activation of Factor 5 aka excess clotting

Question 35

What type of mutation is Factor V Leiden Mutation?

Answer 35

Non-conservative missense mutation

Question 36

Factor V Leiden Mutation is more common in?

Answer 36

Caucasians 2-10%

Question 37

Factor V Leiden Mutation in individuals with VT?

Answer 37

14-21%

Question 38

Testing for Factor V Leiden Mutation if:

Answer 38

Age <50 with MI and smoker

Question 39

Routinely you test for?

Answer 39

Trisomy 21 or 18 | Sicle cell, GALT, biotinidase deficiency, CF, Beta thalassemia, G6PD deficiency and PKU