Testing for Genetic Disease
Quiz yourself by thinking what should be in
each of the black spaces below before clicking
on it to display the answer.
Help!
|
|
||||
|---|---|---|---|---|---|
| Why do genetic testing? | Diagnostic, mutation detection, predictive testing, prenatal testing
🗑
|
||||
| Why is counselling and consent needed? 1. Info can be...? 2. Can indicated individual's...? 3. Can have serious implications for...? 4. Test can give.../...results? | 1. Complex
2. Future health
3. Pregnancy/ children/ relatives
4. Unexpected/ uncertain
🗑
|
||||
| Where can the sample be taken from? | Any tissue with nucleated cells (normally blood)
🗑
|
||||
| Cytogenetic testing - What is added to blood sample first? | Anticoagulant
🗑
|
||||
| Cytogenetic testing - What is purified? | Lymphocytes -> cultured for 3-4 days
🗑
|
||||
| Cytogenetic testing - What needs to be done during mitosis of sample lymphocytes? | Disrupt mitotic spindle to prevent completion
🗑
|
||||
| Cytogenetic testing - The cells are then harvested and treated with what kind of solution? | Hypotonic
🗑
|
||||
| Cytogenetic testing - What is then done with these swelled cells? | Fix to a microscope slide and stain
🗑
|
||||
| Cytogenetic testing - What is then constructed from the images seen down the microscope? | Karyotype
🗑
|
||||
| FISH - What does it stand for? | Fluorescence in situ hybridization
🗑
|
||||
| FISH - What is first constructed? | A DNA 'probe' (copy of target region)
🗑
|
||||
| FISH - How is this DNA 'probe' labelled? | Fluorescently
🗑
|
||||
| FISH - What is the probe applied to? | A target chromosome
🗑
|
||||
| FISH - What two things are done during application of probe to chromosome? | Incubate and hybridize
🗑
|
||||
| FISH - Wash step. What is seen in a normal result? | Probe binds twice to expected chromosomes
🗑
|
||||
| ARRAY-CHG - What does this test allow us to do? | Test thousands/ millions of genomic regions at a time
🗑
|
||||
| ARRAY-CHG - What must be used as a containing to carry out this test? | Inert (glass or metal) welled tray
🗑
|
||||
| ARRAY-CHG - What are fixed to specific wells? | Multiple DNA probes
🗑
|
||||
| ARRAY-CHG - What is added to the well? | Patient DNA sample and reference DNA sample added in equal amounts
🗑
|
||||
| ARRAY-CHG - How is the patient sample and reference sample distinguished? | Different colours
🗑
|
||||
| ARRAY-CHG - How can different coloured wells identify genetic abnormalities? | If reference = test (mixture of two colours), if the colour is predominantly that of reference = deletion in patients DNA, if colour is predominantly that of patients sample = duplication in patients DNA
🗑
|
||||
| DNA Sequencing - How many reactions are set up? | 4
🗑
|
||||
| DNA Sequencing - What are each of these 4 reactions based on? | A,T,C,G - deoxynucleotides for each base with radio labels
🗑
|
||||
| DNA Sequencing - Why are deoxynucleotides used? | They will terminate any existing DNA sequence they are added to
🗑
|
||||
| DNA Sequencing - What must be first done to test DNA? | PCR -> cleaved into fragments of different lengths
🗑
|
||||
| DNA Sequencing - What other 4 components are added to the reaction? | DNA polymerase, nucleotides (normal), primers, fragemented test DNA
🗑
|
||||
| DNA Sequencing - What is produced? | Different fragments of DNA with a deoxynucleotide base terminating each fragment
🗑
|
||||
| DNA Sequencing - What is then done to these fragments? | Electrophoresis to sort them by length
🗑
|
||||
| DNA Sequencing - Those of the same length...? | Will move the same distance in the gel and have the same terminal base
🗑
|
||||
| DNA Sequencing - How is sequence read from gel? | Autoradiography (x-ray), to detect the radio labelled bases, sequence is then determined
🗑
|
||||
| DNA Sequencing - How are modern techniques different? | Flourescently labelled ddNTP terminators that can be read automatically
🗑
|
||||
| DNA Mutations - What does VUS mean in terms of mutations? | Variance of unknown significance
🗑
|
||||
| DNA Mutations - How can you decide if a mutation is pathogenic, benign or VUS? (4) | 1. Significant protein change (nonsense/ frameshift)
2. Other affected family members
3. Not present in control/ normal population
4. The residue is functionally important (e.g. binding site)
🗑
|
||||
| Why do genetic tests have varying sensitivity? 1. Test rarely covers...? 2. Test may miss...? 3. Disease may be due to...? 4. Mutation may be present in only some...? | 1. All of a gene
2. Certain types of changes
3. Changes in another gene
4. Of patients cells (e.g. mosaicism)
🗑
|
||||
| Extras - DNA testing focuses more on introns/exons/boundries? | Exons and intron/exon boundaries
🗑
|
||||
| Extras - Why is DNA testing focused more on exons? | Thought to contain more pathogenic changes
🗑
|
||||
| Extras - Is DNA testing sensitive to larger deletions? | No
🗑
|
||||
| Extras - What does MLPA stand for? | Multiplex Ligation-dependant Probe Amplification
🗑
|
||||
| Extras - What does MLPA show? | Large deletions or duplications
🗑
|
||||
| Extras - Do negative results from DNA testing exclude a diagnoses? (what is exception) | No - except when testing for specific known familial mutation
🗑
|
||||
| Extras - What can gene tests do to assess probability? e.g. | Some are good at giving negative predictive values e.g. for CF and HD
🗑
|
||||
| Extras - What are the two methods of obtaining prenatal genetic information? | Chrionic Villus Smapling (CVS) and Amniocentesis
🗑
|
||||
| Extras - When and how is CVS done? | 10-12 weeks -> placenta biopsy
🗑
|
||||
| Extras - When and how is amniocentesis done? | 15+ weeks -> amniotic fluid
🗑
|
||||
| Extras - CVS/amniocentesis have greatest risk? | CVS (2%), Amnio (1%)
🗑
|
Review the information in the table. When you are ready to quiz yourself you can hide individual columns or the entire table. Then you can click on the empty cells to reveal the answer. Try to recall what will be displayed before clicking the empty cell.
To hide a column, click on the column name.
To hide the entire table, click on the "Hide All" button.
You may also shuffle the rows of the table by clicking on the "Shuffle" button.
Or sort by any of the columns using the down arrow next to any column heading.
If you know all the data on any row, you can temporarily remove it by tapping the trash can to the right of the row.
To hide a column, click on the column name.
To hide the entire table, click on the "Hide All" button.
You may also shuffle the rows of the table by clicking on the "Shuffle" button.
Or sort by any of the columns using the down arrow next to any column heading.
If you know all the data on any row, you can temporarily remove it by tapping the trash can to the right of the row.
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.
Normal Size Small Size show me how
Normal Size Small Size show me how
Created by:
benfenner1
Popular Medical sets