Genetic Testing

Question 1

Diagnostic Testing

Answer 1

confirmatory test or differential diagnosis testing for symptomatic individuals

Question 2

heterozyote screening

Answer 2

within an at-risk family for a disease such as cystic fibrosis

1. founder effect
2. heterozygote advantage

Question 3

pre-symptomatic testing

Answer 3

tests for variants causing or associated with disorders known to be inherited in the family often with *adult-onsetsymptoms”

Question 4

pharmacogenetic testing

Answer 4

Purpose: drug dosing/ adverse reactions
Method: targeted testing

Question 5

predictive testing

Answer 5

purpose: identification of variants causing or associated with adult on-set symptoms

Question 6

prenatal diagnosis (4)

Answer 6

a. amniocentesis
b. chorionic villus sampling
c. percutaneous umbilical blood samplings
d. preimplantation genetic diagnosis

Question 7

Technique: Biochemical Testing

Answer 7

genetic diseases with known biochemical defects (such as inborn errors of metabolism) were diagnosed by enzyme assays

Question 8

Technique: Cytogenetic Testing

Answer 8

1. conventional cytogenetic testing

2. molecular cytogenetics (FISH)

Question 9

Technique: Sequence Analysis

Answer 9

Type: Molecular
Approach: Direct
methods: Sanger Sequencing or whole-exome testing

Question 10

Technique: Targeted Mutation Analysis

Answer 10

Type: Molecular
Approach: Direct
methods: 
Multiplex PCR Analysis
ASO (Allele Specific Oligonucleotide)

Question 11

Technique: Micro-array Analysis

Answer 11

Type: Molecular
Approach: Direct
methods: 
Gene Expression Profiling
Microarray CGH (Comparative Genomic Hybridization)

Question 12

Technique: Indirect molecular testing

Answer 12

Indirect genetic diagnosis determines whether an individual has inherited a chromosome containing the disease gene from his or her parent using DNA polymorphisms linked to the disease gene.

Limitations:

1. need for multiple family members
2. possibility of recombination between matings

Question 13

FISH

Answer 13

Fluoresence In-Situ Hybridization

control probe: identifies the chromosome of interest
tag probe: targets a sequence of interests
resolution: 100 kb (minimum probe size)

Question 14

Whole exome sequencing

Answer 14

to detect mutations in many genes OR
gene panels of interest

ex. panel of alleles known to be associated with cardiomyopathy

Limitations:

1. fails to target sequences in introns
2. by doing the test for just a few mutations, you may not catch ALL possible mutations that cause the diseases