Genetics Intro Flashcards
What are the 2 general uses for genetic testing?
- are these methods directive or non-directive?
- Medical Management
- Directive - Personal Decision Making
- Non-directive
What are the reasons to get a genetic test for Medical Management?
- Diagnosis
- Treatment
- Predictive with a TREATMENT
What are the reasons to get a genetic test for personal decision making?
- Predictive WITHOUT a treatment
- Carrier Testing/screening
- Prenatal Diagnosis
Someone gets a test to see if they are a carrier of Huntington’s, does this fall under the category of Medical Management or Personal Decision making?
- Personal Decision Making because there is no treatment for the disease
You want to see if a patient has CF what kind of test would you start out with?
- Targeted: 75% of CF cases involve a mutation at a single point so you are likely to catch the disease by this test if its there
What are two ways to scan a gene?
- Sequence
- Gene Array
What is population stratification?
- Varying Allele Frequencies across populations
CFTR
- Mode of Inheritance
- % point mutations
- % large deletions/duplications
- Autosomal Recessive
- 90% = point mutations
- 10% = large deletions/duplications
BRCA1
- Mode of Inheritance
- % point mutations
- % large deletions/duplications
- Autosomal Dominant
- 85% = point mutations
- 15% = large deletions/duplications
T or F: CFTR and BRCA1 have a high de novo mutation rate
False, they have a low de novo mutation rate so most cases its an inherited condition
What disease that we’ve studied has a high mutation rate?
- DMD, lot of allelic Heterogeneity
What is the mode of inheritance for DMD?
- X-linked Recessive
What is the mode of inheritance for Huntington’s?
- Autosomal Dominant
T or F: gene panels can be targeted for specific mutations
False, but MUTATION panels are considered targeted because you’re just looking for one mutation here or there that causes the disease
What are the strengths and limitations of targeted testing?
Strengths:
1. HIGH accuracy for the SPECIFIC alleles being tested
- Widely available at low cost
Limitations:
1. No Information about other potentially significant variants
When is Gene Scanning the appropriate method for detecting the cause of a disease?
- If there is lots of allelic heterogeneity aka “private mutations”
T or F: with gene scanning you are likely to uncover many deviations from the normal gene sequence
True - you will likely uncover many SNPs that are benign
With Scanning tests you are likely to still miss a lot of information. What info. are you likely to miss with these types of tests?
- Repetitive Sequences
- Introns usually are not sequenced
With a Scanning Test what does it mean to have:
- Positive Result
- Negative Result
Positive:
- Pathogenic Variant identified
Negative:
- Test Failed to Provide Useful information
- Risk of False Negative
T or F: Benign Variants are always expected in scanning tests
True, also VUSs often accompany but they cannot be used to make any clinical decisions
What are the strengths and limitations to gene scanning?
Strengths:
- Comprehensive
- Good Sensitivity
- Can identify so cheaper targeted testing can be used in the future
Limitations:
- Not all Mutations Will be Detected
- Negative Results do NOT rule out hereditary risk
- Results may be hard to interpret
Why do negative results not rule out hereditary risk in gene scanning?
- It could be the case that there’s a strong family history of the disease but the scan simply misses the pathogenic part
What are the only 2 types of results that can be obtained from a targeted approach?
- Has the mutation
2. Does not have mutation
What type of test would you use for:
- HBOC
- CFTR
HBOC - Sequencing
CFTR - Targeted
What does clinical utility of a genetic test refer to?
The ability of a test to improve outcome
T or F: regardless of gene and general approaches a sequencing test should be used to look for KNOWN FAMILIAL mutations.
False, it a certain mutation occurs within the family then TARGETED approach should be used
