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P Intergrated Y2 > GiM lecture 4 and 5 > Flashcards

GiM lecture 4 and 5 Flashcards

1
Q

Does Multifactoral disease have a genetic component

A

Twin Studies

- monozygotic twins had higher concordance than Dizygotic twins

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2
Q

What are problems with Twin Studies

A

Assumes MZ twin have same environment

DZ twins can share more that half of their genes

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3
Q

What causes phenotypes

A

many genes at different Loci
genes are additive
gaussian distribution curve
influenced by environment too

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4
Q

what disordes show multifactoral inheritance

A

Congenital Malformations - cleft lip, hip dislocation, heart defects, neural tube defects,

Acquired diseases
asthma, autism, cancer, epilepsy, crohns, MS, parkinson,

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5
Q

What is a genome wide association study

A

relate variation in human DNA with disease or trait

estimates population attributable risk

controls match cases and be representative of population

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6
Q

What are Single Nucleotide Polymorphisms

A

common mutations

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7
Q

What is linkage disequilibrium

A

most disease bearing chromosomes come from an ancestral chromosome

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8
Q

What are the genetics of alzhrimers

A

sequence variants at polymorphic locus have affect on age of onset

  • APOE gene - app-lipoprotein - also linked heart disease
    3 types of APOE
    APOE*E2/3/4
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9
Q

How does APOE gene affect alzheimers

A

APOEE4 - increase susceptibility
APOEE2 - protective effect

E4/E4 homozygotes - very early onset

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10
Q

What is age related macular degeneration

A

irreversible central visual dysfunction - degeneration of macula

early deposition of drusen = hall mark risk for AMD

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11
Q

What are the genetic effectors of AMD

What are the environmental factors that increase AMD risk

A

CFH (1q) ARMS2(10q)

Smoking x70 increase

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12
Q

Define Penetrance

A

% with gene who get condition

  • modified by genetic variation
  • modified by environmental factors
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13
Q

What Gatekeepers

A

Monitor and control cell division, death preventing accumulation of mutations

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14
Q

What are caretakers

A

improve genomic stability (repair mutations)

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15
Q

What are landscapers

A

control surrounding stromal environment

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16
Q

A sporadic Defect causes what> and what chance of colorectal cancer?

A

adenomatous polyp

5% risk

17
Q

A Gate keeper Defect causes what> and what chance of colorectal cancer?

A

Multiple adenomatous polyps
>95% risk
FAP

18
Q

A Caretaker Defect causes what> and what chance of colorectal cancer?

A

andenomatous polyp
70% risk
HNPCC

19
Q

a landscaper defect causes what and what chance of colorectal cancer

A

Hamartomatous polyps

10-20% cancer

20
Q

What are tumor suppressor genes

A

protect cells from becoming cancerous
loss = inc risk cancer
APC, BRACA1/2, TP53, Rb

21
Q

What are oncogenes

A

Regluate cell growth and differentiation
gain of function = cancer risk inc
growth and signal transduction factors, RET gene

22
Q

what rule do most cancers obey

A

Knudson’s two hit hypothesis
Recessive at celluar level
Autosomal dominant inheritance

23
Q

examples of cancers that follow an autosomal recessive inheritance pattern

A

MYH associated polyposis, Fanconi anaemia,

Ataxia telangiectasia

24
Q

name mutation types

A

splice site mutations
Deletions, duplications
translocation

25
Q

Signs of Sporadic Cancer

A

Onset older age
one cancer in individual
unaffected family members
cancer type rarely genetic - lung, cervix etc

26
Q

Signs of familial cancer

A

onset younger age
multiple primaries in individual
family members affected
same type/genetically related cancers

27
Q

Explain Retinoblastoma

A

childhood ocular cancer
1/15,000-30,000
classic knudson 2hit
retinoblastoma Rb1 gene

Bilateral cases = usually germline fault
15% “sporadic” actually germ line = new mutation rate is high

increases risk of other cancers

28
Q

FAP Familial Adenomatour Polyposis

A

1% of all bowel cancers
high risk of bowel cancer if untreated
HUNDREDS of bowel polyps
CHRPE, desmoid tumors, osteomas,

fault in APC tumor supresson genes
autosomal dominant inheritance

colonoscopies and cholectomy

29
Q

HNPCC Hereditart Non polposis colorectal cancer

A

2-3% of bowel cancers
polyps common
60-80% risk of bowel cancer
risk of other cancers - endometrial, ovarian, stomach

Error in Mismatch repair genes
MLH1 50%, MSH2 (40%) MSH6 10%
Autosomal dominant inheritance

Amsterdam Criteria

  • 1 member diagnosed colorectal cancer b4 50yo
  • 2 affected generations
  • 3 affected relatives
  • FAP excluded
  • tumours verified by pathology
30
Q

BRCA1/2 genes

A

involved in DNA repair
autosomal dominant inheritance
80% risk breast cancer
BRCA1 40% BRCA2 - 20%

31
Q

Li Fraumeni syndrome

A 
P53 mutations (RARE)
autosomal dominant 
50% risk cancer by 40yo
100% lifetime
avoid radiotherapy - inc cancer risk
poor prognosis

P Intergrated Y2 (13 decks)

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