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Zygosity Determination via Genetic Testing (Blood Sample)

Published: August 9, 2026Updated: August 16, 2026

This test checks your genetic makeup to determine whether you carry one or two copies of a specific gene variant, often used in prenatal or carrier screening for inherited conditions.

Quick summary

["This test helps identify if you are a carrier of a genetic mutation that could be passed to your children."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
55198-6
Short code
Zygosity Bld/T
Synonyms
Zygosity Bld/T
Category
chemistry
Sample
whole-blood
Container
Lavender-top (EDTA)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
molgen
Specimen volume
3 mL
Stability
Room temperature: 4h, Refrigerated: 24h
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What Does This Test Measure?

Zygosity testing analyzes DNA from your blood to detect the presence of a particular genetic variant. It distinguishes between homozygous (two copies) and heterozygous (one copy) states of a gene, often linked to conditions like cystic fibrosis, sickle cell anemia, or other inherited disorders.

Why Might You Need This Test?

This test is commonly ordered during pregnancy to screen for genetic conditions or in preconception planning to assess if you’re a carrier of a recessive genetic trait that could affect your future children.

How Is the Sample Collected?

A small blood sample is drawn from your arm by a healthcare professional. The blood is then processed to extract DNA for analysis.

What Are the Possible Results?

Results will indicate whether you have one or two copies of the gene variant. For example, you might be identified as homozygous (two copies), heterozygous (one copy), or neither (no variant detected).

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

This test is critical for identifying carriers of recessive genetic conditions, allowing healthcare providers to counsel patients on risks to future pregnancies and recommend appropriate genetic counseling or testing.

Short name

Zygosity Blood Test

Frequently asked questions

What does a positive result mean?
A positive result means you carry at least one copy of the gene variant being tested. This does not mean you will develop the associated condition, but it does indicate you could pass the variant to your children.
What if I have a family history of a genetic condition?
If you have a family history, this test can help determine if you’re a carrier of a specific genetic mutation that may increase your risk of passing it to your children, guiding further genetic counseling.
How long does it take to get results?
Results are typically available within 1 to 2 weeks, depending on the laboratory and testing complexity. Follow-up with your healthcare provider is recommended to discuss results and next steps.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy