Genetics & Human Disease Flashcards

1
Q

Each person is estimated to carry how many deleterious genes?

A

5-8

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2
Q

Define Pleiotropism

A

A mutation in a single gene can lead to many effects

CF

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3
Q

Define Genetic Heterogeneity

A

Mutations at several loci may produce the same trait

Diabetes, PKU

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4
Q

Define Autosomal Dominant

A

Only need 1 parent to carry defective gene

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5
Q

Define Autosomal Recessive

A

Both parents must carry defective gene

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6
Q

Two Austosomal Dominant diseases?

A

Huntington’s disease

Familial hypercholesterolemia

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7
Q

Define Huntington’s disease

A

Triplet repeat on chromosome 4

Dysfunctional protein builds up leading to toxicity at the GABA neurons

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8
Q

Define Familial hypercholesterolemia

A

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

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9
Q

Three Autosomal Recessive Disease

A

PKU
CF
Sickle cell anemia

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10
Q

Define PKU

A

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

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11
Q

Define CF

A

Defective chloride ion channel –> thickened mucus secretion

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12
Q

Define Sickle Cell Anemia

A

Defective hemoglobin which precipitates at low O2 tension

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13
Q

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

A

Males

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

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14
Q

Three X-Linked Recessive Diseases

A

Hemophilia A&B
G6PD deficiency
Diabetes insipidus

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15
Q

Define Hemophilia A&B

A

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

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16
Q

Define G6PD deficiency

A

Most common enzyme defect

RBC are unable to repair

17
Q

Define Diabetes insipidus

A

Mutation in AVPR2 gene –> defective vasopressin receptor

18
Q

Majority of disease are?

A

Polygenic: different places for a mutation to occur

19
Q

Define Non-disjunction

A

Failure to separate

20
Q

Example of Non-disjunction

A

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

21
Q

Why do genetic diseases exist?

A
  • We are living longer now

- Mutations may protect us from other disease

22
Q

Define Positive Selection

A

Heritable mutation which confers a survival advantage

23
Q

Examples of Positive Selection

A

Alcohol tolerance

Lactose tolerance

24
Q

How is Sickle Cell Anemia a beneficial mutation?

A

Heterozygotes protected from malaria

25
Q

How is CF a beneficial mutation?

A

Protects against typhoid

26
Q

How is Tay Sachs a beneficial mutation?

A

Protects against TB

27
Q

How is Type AB blood a beneficial mutation?

A

Highly resistant to chlorea

28
Q

Development of disease examples?

A

Multiple sclerosis, asthma

29
Q

Development of drug complications examples?

A

Factor V Leden and OCP’s

30
Q

Define Multiple Sclerosis

A

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

31
Q

What is the most common CV event in young women?

A

Venous Thrombosis

32
Q

How does Venous Thrombosis manifest?

A

Thrombosis of deep leg veins or PE

33
Q

Venous thrombosis interact with?

A

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

34
Q

Define Factor V Leiden Mutation

A

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

35
Q

What type of mutation is Factor V Leiden Mutation?

A

Non-conservative missense mutation

36
Q

Factor V Leiden Mutation is more common in?

A

Caucasians 2-10%

37
Q

Factor V Leiden Mutation in individuals with VT?

A

14-21%

38
Q

Testing for Factor V Leiden Mutation if:

A

Age <50 with MI and smoker

39
Q

Routinely you test for?

A

Trisomy 21 or 18

Sicle cell, GALT, biotinidase deficiency, CF, Beta thalassemia, G6PD deficiency and PKU