Lecture 11

Question 1

What do Genetic testing look for?

Answer 1

Looks for DNA sequences, chromosomes, or proteins

Question 2

If a variation is found, what can happen?

Answer 2

cause a specific disorder
Increase risk for disorder
Be passed down to children

Question 3

How many genetic testing for currently in use?

Answer 3

70,000

Question 4

What are the types of genetic test?

Answer 4

DNA sequence: Targeted single variant, Single gene, panel of genes, and whole exome or genome sequencing.
Chromosomes: Extra or missing, duplication, deletions, rearrangements
Gene expression: Have genes been turned on or off
Biochemical assays: Increased, decreased, or abnormal enzyme or protein activity

Question 5

DNA can be extracted from where?

Answer 5

any cell with a nucleus
Common samples are blood, skin, saliva

Question 6

What is Cell-free DNA?

Answer 6

Small pieces of DNA circulating in the blood, arise when cells die and lyse

Question 7

What is Cell-free DNA (cf DNA) used for?

Answer 7

Used for non-invasive prenatal testing (NIPT)
Used to detect and monitor of some cancers.

Question 8

DNA sequence can be probed indirectly through what?

Answer 8

PCR, restriction digests, and gel electrophoresis

Question 9

DNA Sequence: 4 types meaning
Targeted single variant
Single gene
Panel of genes
Whole exome or whole genome sequencing

Answer 9

Targeted single variant: A single variant that changes the sequence of the whole gene. look for a specific variant in one gene

Single gene: Sequence the whole gene, used when there are multiple variations in the gene that cause a disorder.

Panel of genes: Investigates sequence of multiple genes

Whole exome or whole genome sequencing:
Sequences the bulk of an individual’s genome

Question 10

What is the Genome-Wide Association Studies (GWAS)?

Answer 10

Research to identify genetic markers SNP (Single nucleotide polymorphism) associated with a condition.

It compares genome sequence of large numbers of unaffected people and affected people.

Question 11

Cytogenetic test evaluate what? and used for?

Answer 11

Chromosomes
Used for prenatal screening, infertility, cancer treatment and diagnosis

Question 12

How does the cytogenetic test evaluate chromosomes?

Answer 12

Aneuploidy- missing or extra chromosomes
Abnormal chromosomes structures- Duplication, deletion, or translocation

Question 13

What is Florescence in situ hybridization (FISH)?

Answer 13

An individual’s chromosomes are fixed to a slide, a labelled probe is hybridized to the DNA, and then the slide is viewed through the microscope.
Used to detect chromosomal aneuploidies, deletions, duplications, and translocation.

Question 14

What does diagnostic testing do?

Answer 14

Provides information about genetics of other family members

Question 15

Presymptomatic test vs Predispositional test

Answer 15

Presymptomatic test: A positive result indicates the individual will develop the disorder. Ex: Huntington’s

Predispositional test: a positive result indicates the individual is a higher risk to develop the disorder.
Ex: Mutations for breast cancer

Question 16

What does Carrier testing indicate?

Answer 16

Affected family member
Ethnicity is a risk factor

Question 17

When can screening test happen?

Answer 17

First trimester: Blood test and ultrasound
Second trimester: quad screening for aneuploidy, neural tube defects like down syndrome

Question 18

When does Preimplantation Genetic diagnosis happen?

Answer 18

Performed in conjunction with vitro fertilization.

Question 19

What is newborn testing?

Answer 19

Identifies infants at high risk for diseases for which there is treatment available.
Includes:
Hearing loss
Metabolic disorders
Cystic Fibrosis

Question 20

Forensic testing is used for

Answer 20

to identify individuals rather the genetic disorders.
- Identify victims
-Eliminate suspects
- Paternity testing

Question 21

What is direct to consumer genetic testing?

Answer 21

When people can buy genetic testing and do it at home.
Benefits: Personalized medical information, no approval
Concerns: Inaccurate results
Lack of follow up care
protection of consumer privacy

Question 22

Analytical Validity is

Answer 22

Can the test accurately identify specific genetic variant?

Question 23

Clinical Validity is

Answer 23

Is the genetic variant linked to absence, presence, or risk of specific disorder?

Question 24

Clinical utility

Answer 24

Does the test improve health care through providing diagnosis, treatment, or prevention of the disease?

Question 25

What does Positive results mean?

Answer 25

Specific change was found, may confirm diagnosis, indicate carrier, or identify increased risk.

Question 26

What do negative results mean?

Answer 26

Specific change was not found, can indicate individual is not affected, not a carrier, or not at increased risk

Question 27

What does Inconclusive mean?

Answer 27

Variation may be detected, but variation is not linked to disorder.