Genetics in sudden death Flashcards

1
Q

define penetrance

A

likelihood of having a disease if you have the gene mutation

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2
Q

what does 100% penetrance mean

A

you will always get the disease if you have the mutation

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3
Q

Mendelian disorders have high/low penetrance

A

high

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4
Q

give examples of mendelian inheritance patterns

A

autosomal dominant
autosomal recessive
x-linked

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5
Q

Mendelian disorders are/not apparent in family history

A

are apparent in FH

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6
Q

why is next generation sequencing better than other techniques

A

can sequence multiple genes

cheaper

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7
Q

is a mutation always pathological

A

no, it can be

  • disease causing mutation
  • polymorphism
  • variant of unknown significance
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8
Q

how can the clinical phenotype guide you

A

for certain phenotypes, you can then narrow down the genes to look for mutations

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9
Q

why cant you sequence all the genes in the body

A

because you might find something that you have not discussed with the patient

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10
Q

what is better, to examine the genome or the exome

A

exome - contains the DNA that actually codes for proteins

cheaper

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11
Q

there is a low/high likelihood of effect with a mutation in an intron

A

low

introns are non-coding

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12
Q

what causes a splicing error

A

change to splice sequence 1 or 2 bases into an intron

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13
Q

mutation in an exon has the potential to…

A
  1. change amino acid sequence
  2. stop mutation
  3. frameshift mutation
  4. no effect
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14
Q

how would you describe this mutation:

SMAD4:p.Met157Thr

A

SMAD4 = gene name
p. = peptide
the Methionine at 157 has mutated into Threonine

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15
Q

how would you describe this mutation:
SMAD4:p.Cys162Ter or
SMAD4:p.Cys162*

A

cystine at peptide sequence of SMAD4 at position 162 has mutated to a STOP codon

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16
Q

how would you describe this mutation:

SMAD4:c.471A>T

A

adenine at position 147 in cDNA has mutated into thymine

17
Q

what is cDNA essentially the same as

A

mature mRNA with introns removed

18
Q

why is phenotype important

A

tells you which genes are important

19
Q

examples of genes implicated in a dissecting aortic aneurysm

A

TGFB1+2
Fibrillin
SMAD

20
Q

how is Marfans syndrome inherited

A

AD - fibrillin mutation

21
Q

characteristic features of Marfans

A

ectopia lentis - upward dislocation of lens
aortic aneurysm + dissection
valvular dysfunction
long fingers

22
Q

what is Loeys Dietz syndrome

A

AD inheritance - TBR1/2 mutation
widely spaced eyes
tortuous vessels on angiogram
oddly shaped uvula

23
Q

Mendelian disorders are rare/common

A

rare

24
Q

what can a mutation in LDLR cause

A

familail hypercholesterolaemia

25
Q

consequences of familial hypercholesterolaemia

A
MI at young age 
coronary artery disease
tendon xanthomas 
xanthelasmas
corneal arcus 
cholesterol >7.5
26
Q

what is the most common cause of heart disease in the population

A

multifactorial

but a LDLR mutation would trump that

27
Q

genetic testing is most useful for high/low penetrance disorders

A

high penetrance

28
Q

mutations in difference genes can cause the same phenotype, true or false
what does this mean

A

true

means that these genes often cluster in related pathways