Genetics of Complex Disease Flashcards Preview

IMS > Genetics of Complex Disease > Flashcards

Flashcards in Genetics of Complex Disease Deck (51)
Loading flashcards...
1
Q

What are the 4 types of Genetics of Disease?

A

Single Gene Mutation
Multifactorial/Complex
Chromosomal
Enviromental

2
Q

Describe what Single Gene Mutation is?

A

Rare, mutations in a gene to do with structural proteins and enzymes

3
Q

Describe what Multifactorial is?

A

More than 1 Gene is affected, the Gene expression is on or off

4
Q

Describe what Chromosomal changes are?

A

100’s of genes affected, gain or loss of a chromosome

5
Q

Describe what Environmental factors mean?

A

Very common, could be viral/bacterial infections

6
Q

What is the Definition of Multifactoral Inheritence?

A

Inheritance and expression of a phenotype determined by the action of multiple genes and multiple loci

7
Q

What are the key features of Multifactoral Inheritance?

A
  • Gene contributes to small amount of final phenotype
  • Multiple genes not recessive/dominant
  • multiple genes to segregate in Mendelian manner NOT PHENOTYPE
8
Q

What are Monogenic Diseases?

A

Single strong high penetrate phenotype, rare and other genes affect phenotype severity

9
Q

What are Polygenic diseases?

A

Very common, low penetrant phenotypes, not dominated by one gene, pedigrees comple and enviroment reduces pentrance

10
Q

What does Pentrance mean?

A

Fraction of cases carrying a given gene that manifests in a specific phenotype

11
Q

What would be the effect or a Fully Pentrant single gene?

A

No effect of other genes or enviroment

12
Q

What would be the effect of low-pentrance?

A

Genes along with other genetic factors determine a persons susceptibility to disease

13
Q

What would be the effect of Multifactorial?

A

Genetics determines susceptibility but has low penetrance e.g multiple sclerosis

14
Q

What are the 2 Factors that cause any trait?

A

Genetics

Enviroment

15
Q

What are some Examples of Polygenic complex disease?

A
Hypertension
Obesity
Diabetes
Chrons
Cancer
Autism
16
Q

Why study genetics of multifactorial disease?

A

Identify individual with increased risk of disease
Identify targets for better therapy
Untangle complex gene-enviro interactions

17
Q

Why is Complex inheritance an underlying factor for most common human diseases?

A

Multifaceted interactions of genotypes at multiple loci

Environmental factors that trigger acceleate or worsen disease

18
Q

What percentage of the population have complex disorders?

A

60

19
Q

What is Polygenic Inheritance?

A

Traits quantified by measurement

More than 2 genes contributing to phenotype

20
Q

Give an Example of Polygenic Inheritance?

A

Adult Male height

21
Q

How is Adult Male height measured?

A

Median of Population
Bell curbe
Quantitive traits at 180 genetic loci

22
Q

What Methods allow to study multifactorial traits?

A

Threshold Model
Recurrence Risk
Liability Threshold

23
Q

Describe Threshold model?

A

Frequency of disorder of relatives compared to frequency of disorder with population

24
Q

Describe Recurrence risk?

A

Estimates risk that disease will recur

25
Q

Describe Liability threshold?

A

Measures disease state of indiv, when alleles push distrubtion towards threshold termed Risk/Susceptibility alleles

26
Q

How do we know a complex disease has a genetic component?

A

Heritability - proportion of disease variation, defined as number between 0 and 1

27
Q

What number = High genetic influence?

A

1

28
Q

What number = NO genetic infulence?

A

0

29
Q

What are monozygotic twins?

A

Identical - single fertilization

30
Q

What are dizygotic twins?

A

Fraternal - independent fertilization events, share half there genes

31
Q

What is Concordance?

A

Probability that twins will both have the disease if 1 has the disease

32
Q

What type of Twins have a higher Concordance with diseases?

A

Monozygotic

33
Q

How much Familial Risk is accounted in Familial Breast cancer?

A

< 30 %

34
Q

What is Autism?

A

Great difficulty in communicating, forming relationships - strongly influenced by genetics

35
Q

What is an Allele?

A

One of a number of alternative forms of the same gene

36
Q

What is a Single Nucleotide Polymorphism (SNP) ?

A

DNA sequence variation that occurs when a single nucleotide in the genome sequence is altered at same genetic location between different chromosomes

37
Q

Describe SNP?

A

Variation must occur in >1 % of the population, act as biological markers - help identify genes associated with disease

38
Q

How can SNP’s be useful?

A

Used to track inheritance of diseases in families

39
Q

What are SNP’s used as markers to map?

A

Haplotypes

40
Q

What are Haplotypes?

A

Disease-linked genomic loci physically linked on a chromosome and segregate together

41
Q

What is GWAS?

A

genome-wide association study

42
Q

Describe Chromosomal disorders?

A

Usually de novo can be inherited
Thousands of genes involved
Multiple organs affected at multiple stages

43
Q

What is an Aneuploidy?

A

Presence of an Abnormal number of chromosomes in a cell

44
Q

What are the Sex chromosomes?

A

Triple X syndrome - 47 XXX
Klinefelter syndrom 47 XXY
XYY syndrome - 47 XYY
Turner Syndrome 45 X0

45
Q

What are the Autosomal chromosomes?

A

Trisomy 21 - down syndrome
Trisomy 18 - edward syndrome
Trisomy 13 - Patau syndrome

46
Q

What is DiGeorge syndrome?

A

Deletion of band 11.2 on long arm of chr 22 , 45 genes

47
Q

What are some Symptons of DiGeorge syndrome?

A

Congenital cardiac defects, facial dysmorphia, T-cell

48
Q

What is the Cause for T21 Down syndrome?

A

Mieotic non-disjunction

49
Q

What is non-disjunction?

A

Failure of chromatids to seperate into 2 chromosomes

50
Q

What is the Pedigree, Traits and Underlying cause for Mendelian?

A

Predictable inheritance pattern
Independent action of single gene
Mutation in this gene necessary for phenotype

51
Q

What is the Pedigree, Traits and Underlying cause for Complex?

A

Familial clustering but not predictable inheritance pattern
Interactions between multiple genetic and enviro factors
Genetic variations increase susceptibility

Decks in IMS Class (53):