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Flashcards in Genetic Basis of Complex Inheritance Deck (51)
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1

What does mendelian inheritance involve

The Law of Dominance
The Law of Segregation
The Law of Independent Assortment

2

What are the principles of non-mendelian inheritance

Does not fit in with Mendelian’s Law (e.g.
Gene conversion or Intermediate phenotype)

3

What kind of non-mendelian inheritance patterns are there

Incomplete Penetrance
Genomic Imprinting
Extranuclear Inheritance
Anticipation

4

What mechanisms cause incomplete penetrance

Environmental factor
Genetic Modifiers

5

What mechanisms cause genomic imprininting

Variants from parents

6

What mechanisms cause extranuclear inheritant

e.g. mitochondria mutations

7

What mechanisms cause anticipation

e.g. triplet repeat expansion

8

What is penetrance

The frequency with which a trait is manifested by individuals carrying the gene

9

What mutation causes cystic fibrosis (CF)

Mutation in CFTR
Autosomal recessive inheritance

10

What is the prevalence of CF in European Caucasians

1 in 2,500 (4% carriers)

11

What is the prevalence of CF in Africans

1 in 13,000

12

What is the prevalence of CF in Asians

Rare

13

How can the CF phenotype be variable

In severity and affected organs

14

What organs can be affected in CF

Sinuses (sinusitis infection)
Lungs
Skin
Liver
Pancreas
Intestines
Reproductive organs

15

How are the lungs, skin, liver. pancreas and intestines affected in CF

Lungs - thick sticky mucus build up, bacterial infection and widened airways
Skin - sweat glads produce salty sweat
Liver - blocked biliary ducts
Pancreas - blocked pancreatic ducts
Intestines - cannot fully absorb nutrients

16

What are gene modifiers

Genes that have small quantitative effects on the level of expression of another gene
It may involve polymorphism

17

What environmental factors can affect the severity of CF in organs

Lifestyle
Diet
Smoke
Alcohol
Drug
Stress
Air pollution
Chemicals
Infection

18

What else apart from genetic factors can explain the prevalence of increased diabetes

Rapid changes in lifestyle and risk factors such as:
Obesity
Unhealthy diets
Physical inactivity

19

What factors are seen in genetic diseases

Rare
Genetics simple
Uni-factorial
High recurrence rate

20

What factors are seen in enviromental diseases

Common
Genetics complex
Multi-factorial
Low recurrence rate

21

Give some examples of human diseases mainly caused by genetics

Haemophilia
Osteogenesis imperfecta
Huntington’s Disease
Familial motor neurone disease

22

Give some examples of human diseases caused by both genetics and environmental factors

Manic depressive psychosis
Ischaemic heart disease
Ankylosing spondylitis
Peptic ulcer Diabetes

23

Give some examples of human diseases mainly caused by enviromental factors

TB
Scurvy

24

What is genomic imprinitng

Genes expressed from only one chromosome
Parent-of-origin dependent

25

What is 5’ Methylcytosine (mC)

Occurs from DNA methylation of cytosine
It induces the structural adaptation of chromosomal region so as to perpetuate altered activity states

26

What genetic mechanisms of error are there

Deletions
Point mutations
Imprinting errors
Uniparental disomy

27

What is uniparental disomy

Inheritance of a chromosome pair from one parental origin

28

How can uniparental disomy occur

From:
Non-disjunction of a trisomy zygote
Duplication of a monosomy zygote
Non-disjunction or duplication of disomy zygote

29

What does the recombination of a zygote formed from gamates that have undergone mitotic error produce

Partial uniparental disomy

30

What can uniparental diploidy cause

Gynogenic
Androgenic