Lecture 3 Flashcards

1
Q

what is the purpose of genetic testing

A
  • diagnostic testing
  • carrier testing
  • pre-symptomatic and predictive testing
  • prenatal testing
  • preimplantation testing
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2
Q

what is diagnostic testing

A

testing to confirm a suspected diagnosis or to aid diagnosis

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3
Q

explain carrier testing

A

testing someone who is usually healthy but may be a carrier of a recessive or X linked genetic condition

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4
Q

what is the importance of a correct diagnosis

A
  • effective and timely treatment
  • access to healthcare support
  • may result in lifestyle changes for patient
  • may inform life planning and reproductive decision making
  • emotional impact of “not knowing “
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5
Q

why might someone undergo carrier testing

A
  • individuals who have a family history of a genetic disorder
  • people in certain ethnic groups with an increased risk of specific genetic conditions
  • primarily used to guide and inform for reproductive choices
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6
Q

predictive testing

A

can identify mutations that increase a persons risk of developing disorders with a genetic basis
- eg. Bracca 1 gene testing

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7
Q

prenatal testing

A

used to detect changes in genes or chromosomes before birth

(used to look for specific conditions)

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8
Q

harmony test

A

a test the screens for chromosomal abnormalities
- a prenatal test
- at the moment is a private test

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9
Q

preimplantation genetic diagnosis

A

used to detect genetic changes in embryos created using IVF

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10
Q

pre-symptomatic testing

A

can determine whether a person will develop a genetic disorder before signs or symptoms

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11
Q

molecular diagnostics

A

a range of diagnostic tests that detect variants (mutations) in DNA

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12
Q

cytogenetic diagnostics

A

the examination of chromosomes to determine genetic abnormalities

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13
Q

sources of DNA when testing

A

blood
saliva
tissue samples
bone
amniotic fluid
CVS

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14
Q

where does the DNA sample come from in prenatal testing

A

he developing fetus

a thin needle is put through the mothers abdominal wall with ultrasound guidance

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15
Q

what are three different techniques used in cytogenetics

A
  • karyotype (G banding)
  • Fluorescence in situ hybridization FISH
  • Array CGH
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16
Q

explain karyotype preparation with G banding

A
  • obtain a blood sample
  • colcemid is added to prevent spindle from forming therefore keeping cells in metaphase
  • cells are collected
  • treated with hypotonic solution to swell the cells
  • cells fixed onto slides
  • stained with Giemsa
  • banding patterns are analyzed
  • karyotype is made by arranging chromosomes into pairs
17
Q

what type of syndrome does the karyotype appear normal

A

microdeletion syndromes

18
Q

FISH

A

lab technique for detecting a specific DNA sequence on a chromosome, relies on exposing chromosome to a probe that is fluorescently labelled

19
Q

what is a limitation of array CGH

A

it can only tell us if there is loses and gains in chromosomes, not if there is any structural changes

20
Q

what is a limitation of G-banding

A

time consuming
low resolution

21
Q

what is a limitation of FISH

A

targeted analysis

22
Q

what is PCR

A

polymerase chain reaction
- a powerful laboratory technique used in genetics to amplify a specific segment of DNA. allows researchers to make millions of copies of a particular DNA sequence, making it easier to study and analyze.

23
Q

what are the key steps in PCR

A
  • denature the DNA
  • temperature is increased to make it single stranded
  • primer then needed to anneal the DNA at different temperatures depending on the components
  • DNA polymerase expands the DNA by adding nucleotides
24
Q

Huntington disease

A
  • genetic disorder that affects the brain
  • ## caused be abnormal increase in CAG repeats
25
Q

how would you design your primers for fragment sizing

A
  • CAG is the variable part
  • if you design your primers to flank either side of the CAG repeat so then you can measure and tell someone how long their CAG repeat is