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Flashcards in Genetic Basis of Complex Inheritance Deck (46)
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1
Q

What are the 3 laws of mendelian inheritance?

A

Dominance
Segregation
Independent Assortment

2
Q

What mechanisms cause incomplete penetrance?

A

Environmental

Genetic modifiers

3
Q

What mechanisms cause genomic imprinting?

A

Variants from parents

4
Q

What mechanisms cause extranuclear inheritance?

A

Mitochondria mutations

5
Q

What mechanisms cause anticipation?

A

Triplet repeat expansion.

6
Q

Define penetrance.

A

Frequency with which a trait is manifested by individuals carrying the gene.

7
Q

What is the penetrance of cystic fibrosis?

A

100%

8
Q

What is the penetrance of breast cancer?

A

70-80%

9
Q

What is allele frequency?

A

The variation of alleles in a population.

10
Q

What is cystic fibrosis caused by?

A

Mutation in CFTR (Autosomal recessive).

11
Q

What is the prevalence in european caucasians?

A

1 in 2500

12
Q

What two phenotypes are variable in cystic fibrosis?

A

Severity

Affected organs

13
Q

What builds up in cystic fibrosis?

A

Mucus

14
Q

What are genetic modifiers?

A

Genes that have small quantitative effects on the level of expression of another gene.

15
Q

What are included in environmental factors?

A
Lifestyle
Diet
Smoke
Alcohol
Drug
Stress
Air pollution
16
Q

What does polymorphism mean?

A

May occur in different forms, i.e cystic fibrosis can have different forms which is why it affects people differently.

17
Q

What are the 4 features of genetic factors?

A

Rare
Simple
Uni-factorial
High recurrence

18
Q

What are the 4 features of environmental factors?

A

Common
Complex
Multi-factorial
Low recurrence

19
Q

What is genomic imprinting?

A

Genes expressed from only one chromosome.

20
Q

What is genomic imprinting dependent on?

A

Parent-of-origin.

21
Q

What are epigenetic modifications?

A

Heritable changes in gene function which can’t be explained by changes in DNA sequences.

22
Q

What are deletions, point mutations, imprinting errors and uniparental disomy examples of?

A

Genetic mechanisms

23
Q

Why do imprinted genes have a higher risk of disease?

A

Expression is only from a single copy

24
Q

What is uniparental disomy?

A

Inheritance of a chromosome pair from one parental origin.

25
Q

What happens during UPD trisomy rescue?

A

Nondisjuction

26
Q

What happens during UPD monosomy rescue?

A

Duplication

27
Q

What happens during UPD mitotic error?

A

Nondisjuction/duplication

Recombination

28
Q

What is the name of UPD with 2 maternal genomes?

A

Gynogenic

29
Q

What is the name of UPD with 2 paternal genomes?

A

Angrogenic

30
Q

What forms in gynogenic UPD?

A

Ovarian teratoma (Non-malignant)

31
Q

What forms in androgenic UPD?

A

Hydatidiform mole

32
Q

What two disorders come from chromosomal region 15q11-13?

A

Angelman Syndrome

Prader-Willi Syndrome

33
Q

Why can two different disorders come from the same chromosomal region?

A

Parental and maternal differentiation.

34
Q

Where do we usually inherit mitochondria from?

A

Mother

35
Q

What type of form is mitochondria?

A

Circular

36
Q

How many genes do mitochondria have?

A

37

2rRNA, 22tRNA, 13 coding regions

37
Q

Why do mitochondria have a higher mutation rate?

A

Lack of efficient DNA repair
Lack of protective proteins
Damaged by ROS (free radicals)

38
Q

What is the disease chance in homoplasmy?

A

No disease

39
Q

What is the disease chance in heteroplasmy?

A

No/mild disease

Disease

40
Q

How many mitochondria are in cells?

A

Up to thousands

41
Q

What type of tissues do mitochondrial diseases affect?

A

Tissues with high metabolic demand.

42
Q

What are the 3 major myopathies?

A

MERRF
MELAS
CPEA

43
Q

What is Leigh’s syndrome?

A

Encephalopathy

44
Q

How did a three-parent baby work?

A

Nucleus from mother put into patient’s egg. Patient’s egg fertilised by father’s sperm.

45
Q

What is anticipation?

A

Disease presents at earlier age and/or increasing severity in succeeding generations.

46
Q

What are 3 examples of triplet repeat diseases?

A

Huntingtons’s
Myotonic dystrophy
Fragile X Syndrome