Help Me Understand Genetics
Genetic Testing
Reprinted from MedlinePlus Genetics
U.S. National Library of Medicine
National Institutes of Health
Department of Health & Human Services
, CONTENTS
1 What is genetic testing? 1
2 What are the different types of genetic tests? 3
3 What are the uses of genetic testing? 6
4 How is genetic testing done? 8
5 What is informed consent? 9
6 How can I be sure a genetic test is valid and useful? 11
7 What do the results of genetic tests mean? 13
8 What is the cost of genetic testing, and how long does it take to get
the results? 15
9 Will health insurance cover the costs of genetic testing? 16
10 What are the benefits of genetic testing? 17
11 What are the risks and limitations of genetic testing? 18
12 What is genetic discrimination? 19
13 Can genes be patented? 20
14 How are genetic screening tests different from genetic diagnostic
tests? 21
Reprinted from MedlinePlus Genetics (https://medlineplus.gov/genetics/) i
,15 How does genetic testing in a research setting differ from clinical
genetic testing? 23
16 What are whole exome sequencing and whole genome sequencing?
24
17 What are secondary findings from genetic testing? 26
18 What is noninvasive prenatal testing (NIPT) and what disorders can
it screen for? 29
19 What is circulating tumor DNA and how is it used to diagnose and
manage cancer? 32
Reprinted from MedlinePlus Genetics (https://medlineplus.gov/genetics/) ii
, Genetic Testing
1 What is genetic testing?
Genetic testing is a type of medical test that identifies changes in genes, chromosomes,
or proteins. The results of a genetic test can confirm or rule out a suspected genetic
condition or help determine a person’s chance of developing or passing on a genetic
disorder. More than 77,000 genetic tests are currently in use, and others are being
developed.
Genetic testing involves looking for changes in:
• Genes: Gene tests study DNA sequences to identify variations (mutations) in genes
that can cause or increase the risk of a genetic disorder. Gene tests can be narrow
or large in scope, analyzing an individual DNA building block (nucleotide), one or
more genes, or all of a person’s DNA (which is known as their genome).
• Chromosomes: Chromosomal genetic tests analyze whole chromosomes or long
lengths of DNA to see if there are large genetic changes, such as an extra copy of a
chromosome, that cause a genetic condition.
• Proteins: Biochemical genetic tests study the amount or activity level of proteins or
enzymes; abnormalities in either can indicate changes to the DNA that result in a
genetic disorder.
Genetic testing is voluntary. Because testing has benefits as well as limitations and
risks, the decision about whether to be tested is a personal and complex one. A
geneticist or genetic counselor can help by providing information about the pros and
cons of the test and discussing the social and emotional aspects of testing.
For general information about genetic testing:
MedlinePlus offers a list of links to information about genetic testing (https://medlineplus
.gov/genetictesting.html).
The Genetic Testing Registry (https://www.ncbi.nlm.nih.gov/gtr/) is a service from the
National Library of Medicine that provides a searchable database of genetic tests that
have submitted by providers and laboratories.
The National Human Genome Research Institute provides an overview of this topic in its
Frequently Asked Questions About Genetic Testing (https://www.genome.gov/FAQ/Gen
etic-Testing). Additional information about genetic testing legislation, policy, and
oversight (https://www.genome.gov/about-genomics/policy-issues/Regulation-of-Geneti
c-Tests) is available from the Institute.
You can also search for clinical trials involving genetic testing. ClinicalTrials.gov (https://
clinicaltrials.gov/), a service of the National Institutes of Health, provides easy access to
information on clinical trials. You can search for specific trials or browse by condition or
trial sponsor. You may wish to refer to a list of studies related to genetic testing (https://c
Reprinted from MedlinePlus Genetics (https://medlineplus.gov/genetics/) 1
Genetic Testing
Reprinted from MedlinePlus Genetics
U.S. National Library of Medicine
National Institutes of Health
Department of Health & Human Services
, CONTENTS
1 What is genetic testing? 1
2 What are the different types of genetic tests? 3
3 What are the uses of genetic testing? 6
4 How is genetic testing done? 8
5 What is informed consent? 9
6 How can I be sure a genetic test is valid and useful? 11
7 What do the results of genetic tests mean? 13
8 What is the cost of genetic testing, and how long does it take to get
the results? 15
9 Will health insurance cover the costs of genetic testing? 16
10 What are the benefits of genetic testing? 17
11 What are the risks and limitations of genetic testing? 18
12 What is genetic discrimination? 19
13 Can genes be patented? 20
14 How are genetic screening tests different from genetic diagnostic
tests? 21
Reprinted from MedlinePlus Genetics (https://medlineplus.gov/genetics/) i
,15 How does genetic testing in a research setting differ from clinical
genetic testing? 23
16 What are whole exome sequencing and whole genome sequencing?
24
17 What are secondary findings from genetic testing? 26
18 What is noninvasive prenatal testing (NIPT) and what disorders can
it screen for? 29
19 What is circulating tumor DNA and how is it used to diagnose and
manage cancer? 32
Reprinted from MedlinePlus Genetics (https://medlineplus.gov/genetics/) ii
, Genetic Testing
1 What is genetic testing?
Genetic testing is a type of medical test that identifies changes in genes, chromosomes,
or proteins. The results of a genetic test can confirm or rule out a suspected genetic
condition or help determine a person’s chance of developing or passing on a genetic
disorder. More than 77,000 genetic tests are currently in use, and others are being
developed.
Genetic testing involves looking for changes in:
• Genes: Gene tests study DNA sequences to identify variations (mutations) in genes
that can cause or increase the risk of a genetic disorder. Gene tests can be narrow
or large in scope, analyzing an individual DNA building block (nucleotide), one or
more genes, or all of a person’s DNA (which is known as their genome).
• Chromosomes: Chromosomal genetic tests analyze whole chromosomes or long
lengths of DNA to see if there are large genetic changes, such as an extra copy of a
chromosome, that cause a genetic condition.
• Proteins: Biochemical genetic tests study the amount or activity level of proteins or
enzymes; abnormalities in either can indicate changes to the DNA that result in a
genetic disorder.
Genetic testing is voluntary. Because testing has benefits as well as limitations and
risks, the decision about whether to be tested is a personal and complex one. A
geneticist or genetic counselor can help by providing information about the pros and
cons of the test and discussing the social and emotional aspects of testing.
For general information about genetic testing:
MedlinePlus offers a list of links to information about genetic testing (https://medlineplus
.gov/genetictesting.html).
The Genetic Testing Registry (https://www.ncbi.nlm.nih.gov/gtr/) is a service from the
National Library of Medicine that provides a searchable database of genetic tests that
have submitted by providers and laboratories.
The National Human Genome Research Institute provides an overview of this topic in its
Frequently Asked Questions About Genetic Testing (https://www.genome.gov/FAQ/Gen
etic-Testing). Additional information about genetic testing legislation, policy, and
oversight (https://www.genome.gov/about-genomics/policy-issues/Regulation-of-Geneti
c-Tests) is available from the Institute.
You can also search for clinical trials involving genetic testing. ClinicalTrials.gov (https://
clinicaltrials.gov/), a service of the National Institutes of Health, provides easy access to
information on clinical trials. You can search for specific trials or browse by condition or
trial sponsor. You may wish to refer to a list of studies related to genetic testing (https://c
Reprinted from MedlinePlus Genetics (https://medlineplus.gov/genetics/) 1
