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Genetic Counseling and Testing

What is genetic counseling?

Genetic counseling provides information to patients and families on how genes might affect your family and the risk of developing certain health conditions.

Genes are sections of DNA that are in every cell. Genes tell cells how to function, grow, and divide. They determine traits, such as hair and eye color.

Genetic counseling can help you understand:

  • How certain genes might increase the risk of certain diseases
  • Genetic testing and screening tests that are available
  • What test results mean for you, your child, and other family members

This information can help you make decisions about your child’s care and treatment.

Genome statue

Genetic counseling can help you understand inherited conditions so you can make informed health decisions.

How a genetic counselor can help

A genetic counselor is a health care professional who has specialized training in medical genetics and counseling. They work closely with doctors and other members of your care team.

They can help you:

  • Understand family history and risk of inherited conditions: A genetic counselor will review your family’s medical history and talk with you about inherited conditions (passed down in families). They will ask you about diseases in family members and the ages when the problems developed. This helps the counselor know if there is more disease than normal in your family or if the disease happened at an earlier age than expected.
  • Plan for genetic testing: Your genetic counselor can help you plan for lab tests that can detect gene changes (mutations) that cause disease. This is known as genetic testing. Talk to your care team about:
    • Which genetic tests they recommend
    • What the tests results may or may not show
    • How to get tested
    • How you will be notified of the results
    • What the next steps might be
  • Use test results to develop a plan of care: When the test results are ready, your genetic counselor will explain the test results to you. They will let you know if other family members might have a greater risk of disease.

Your genetic counselor can also help you learn about related research studies and help you find medical specialists and services in your local area. Genetic counseling might include information about planning a family and options for prenatal genetic testing.

Counselors can also help families understand the Genetic Information Non-Discrimination Act. This is a federal law in the United States that protects people from discrimination based on their genetic information.

To find a genetic counselor, talk to your health care provider or visit Personalized Care for Your Genetic Health from the National Society of Genetic Counselors.

Genetic testing

Genetic testing looks for gene changes (mutations) or differences in a person’s genes. Not all genetic changes are harmful. Some changes may have helpful effects on a person’s health. Others cause no noticeable effect or slight effects.

Some gene mutations result in a disorder or syndrome. This means that there is a higher-than-normal risk for disease.

Genetic testing can also show if family members have inherited the same mutation, even if they do not show signs of the disease.

Types of genetic tests

There are many kinds of genetic tests. Your health care provider will talk to you about genetic testing and get your consent to test. They will usually collect a small amount of blood or saliva (spit). Sometimes they collect a small tissue sample. Then they send the sample to a lab for testing.

The specific test will depend on the genetic condition and the type of gene change being examined.

  1. Karyotype test

    A karyotype is a picture of the chromosomes in cells. Chromosomes are thread-like structures that hold the genes. This test can show:

    • Large, missing pieces of chromosomes
    • Extra pieces of chromosomes
    • Pieces of chromosomes that are out of their normal order
    • Missing or extra whole chromosomes

  2. Fluorescence in situ hybridization test (FISH test)

    FISH testing uses colorful markers that light up brightly under a microscope (fluorescent probes). This helps doctors see specific areas of the chromosomes better. It does not examine all the chromosomes. This test can show:

    • 1 or more missing chromosomes
    • Extra chromosomes
    • Chromosomes that are out of their normal order

  3. SNP chromosome microarray test

    Changes in chromosomes may be so small that they cannot be seen by karyotype. A SNP chromosome microarray test finds very small changes in all the chromosomes. But this test does not show if chromosome pieces are out of order. This test can show:

    • Missing or extra pieces of chromosomes
    • Whether both copies of a chromosome pair were inherited only from 1 parent or both parents

  4. Methylation analysis test

    People get 1 copy of each gene from their mother and 1 from their father. Usually, these genes both work the same way. Genes are “turned on” or “turned off,” depending on the type of cell they are in. This is done by a feature on the surface of the cell called a methyl group, which acts like a switch. This is called “methylation.” But for some genes, only 1 copy is turned on or off.

    Methylation testing checks to see if the process is working correctly on a specific gene or chromosome. This test can show:

    • If specific areas of a certain chromosome have genes turned on or off 
    • If copies or pieces of chromosomes were inherited from a single parent, rather than from each parent

  5. Uniparental disomy test (UPD)

    Typically, a person inherits 1 copy of each chromosome from their mother and 1 copy from their father. But a person can have 2 copies of an entire chromosome or two copies of a specific part of a chromosome that both come from 1 parent. This is called uniparental disomy or UPD.

    This test finds uniparental disomy on the specific chromosome or chromosome area that is tested.

  6. DNA sequencing test

    The building blocks of DNA, nucleotides, come together in a specific order, or code, and form genes. Genes carry instructions for cells. DNA sequencing reads the code for the DNA building blocks (A, T, C, G) that make up the genes. It looks for any changes from the normal code. DNA sequencing can be done on 1 gene or on multiple genes. Whole genome sequencing is when all a person’s genes are tested at once. Gene panel sequencing can look at a group of genes related to a certain condition.

    Sequencing can show if:

    • there is a change in sequence of the DNA letters that make up 1 or more genes
    • DNA letters are missing or if extra letters were added

    Usually, this test does not show larger areas of DNA that are missing, extra, or out of the normal order.

  7. Deletion/duplication test

    Deletion/duplication testing looks for any missing or extra pieces within a specific gene. These changes can change how well a gene works. This test can show if there are missing or extra pieces of DNA, which are too small to find using a karyotype, FISH, or SNP chromosome microarray testing.

Questions to ask your care team

  • How can a genetic counselor help?
  • What medical or family history information do I need to share with my genetic counselor?
  • What types of genetic tests are available, and which ones do you recommend?
  • What are the benefits and limitations of genetic tests?
  • What is the process for genetic testing?
  • How long will it take to get the results, and how will I receive them?
  • Does insurance cover genetic counseling and testing?

Key points about genetic counseling and testing

  • Genetic counseling helps people understand their genes and how they can affect their health.
  • A genetic counselor can help you understand genetic risks based on family history and the results of genetic testing.
  • Genetic testing looks for changes or differences in a person’s genes.
  • Information from genetic counseling and testing can help you make informed decisions about health care.

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Reviewed: September 2024

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