Skip to content
How It Works
Explore
Ask a Question Resources Pricing
Who It's For
Patients
Decode results, prep for appointments, weigh options.
Caregivers & advocates
Carry the research load for someone you love.
Providers & clinicians
Resources for patients in your practice.
Log In Sign Up
PubMed This is a summary of 19 peer-reviewed journal articles Updated
Clinical immunology

What Is Genetic Testing's Role in Primary Immunodeficiency?

At a Glance

Genetic testing can identify disease-causing variants behind primary immunodeficiency when blood tests cannot explain the problem. A result may guide treatment, monitoring, infection prevention, and family testing, while a negative result does not rule out an immune disorder.

In this answer

4 sections

01

The Limits of Standard Blood Tests

02

How Broad Genetic Testing Works

03

Before and After Testing: Understanding the Results

04

Why Finding the Exact Gene Matters

Standard blood tests and functional immunology tests are crucial for showing how your immune system is failing, such as whether you are missing certain white blood cells or failing to make antibodies [1][2]. However, they cannot always tell you why. Primary immunodeficiency (PI) is part of a broader group of disorders now called inborn errors of immunity (IEI), which are caused by disease-causing changes (variants) in any of over 500 different genes [3][4]. Genetic testing looks at your DNA to find a possible genetic explanation [5]. Identifying a specific variant can help guide a personalized treatment plan [6].

The Limits of Standard Blood Tests

Initial immune testing involves counting immune cells and evaluating their function [3][1]. Tests like a complete blood count (CBC), immunoglobulin (antibody) levels, and vaccine response assays can identify broad defects, like a lack of protection against infection [1][2]. Flow cytometry (a test that analyzes cells in a fluid) can rapidly pinpoint which immune cells are missing, abnormal, or lacking a particular protein [7][8].

However, these tests have limitations. Some people with genetically defined IEI have normal or only slightly reduced immunoglobulin levels [9]. More importantly, knowing that a specific part of the immune system is broken doesn’t necessarily explain the root cause.

How Broad Genetic Testing Works

When standard tests show an immune defect, or if your symptoms are severe, early-onset, or run in your family, doctors often recommend genetic testing alongside genetic counseling [4][3]. There are different approaches depending on your specific symptoms:

Test Type What It Examines Strengths Limitations
Targeted Panel A focused group of suspected genes Highly reliable for known conditions with fewer uncertain findings May miss genes not included in the panel
Whole Exome Sequencing (WES) The protein-coding regions of your DNA A broad approach when the exact diagnosis isn’t obvious Can miss structural changes or non-coding variants
Whole Genome Sequencing (WGS) Nearly all your DNA Can find complex structural changes Higher chance of finding uncertain or unrelated health risks

Because there are hundreds of genes that can cause inborn errors of immunity, broad testing like WES can be useful when the exact diagnosis isn’t obvious [3][4]. WES successfully finds a genetic cause in an estimated 38% to 42% of suspected cases across various studies, though your individual chance depends on your specific symptoms and family history [10][11]. A negative result doesn’t mean you don’t have an immune disorder, as WES can sometimes miss complex changes like copy-number variants (missing or extra stretches of DNA) [12][13].

Before and After Testing: Understanding the Results

Before testing, you will likely meet with a genetic counselor to discuss consent, privacy, and what the test might find. Genetic testing can return several types of results:

Result Type What It Means Next Steps
Pathogenic or Likely Pathogenic Variant A disease-causing change was found that explains your symptoms. Can help guide treatment and monitoring.
Negative Result No clear genetic cause was found. Your diagnosis is still valid. Your doctor may recommend different testing or reanalyze the data later.
Variant of Uncertain Significance (VUS) A DNA change was found, but it is not yet known if it causes disease. Treatment is not usually changed based solely on a VUS.
Incidental or Secondary Findings Genetic risks for conditions unrelated to your immune system were found. You can often choose beforehand whether or not you want to learn about these risks.

Why Finding the Exact Gene Matters

While care is always based on your overall health, immune function, and symptoms, pinpointing a disease-causing variant can help guide your care. In one large multicenter study, finding the specific genetic cause changed medical management for a majority of those diagnosed [6]. Knowing your exact variant allows your care team to:

  • Personalize treatment: Some variants may respond to specific targeted therapies, such as JAK inhibitors (specialized medicines for certain immune disorders that require careful monitoring for side effects), while select severe conditions might prompt consideration of a hematopoietic stem cell transplant (a procedure with substantial risks that replaces your blood-forming stem cells) [6][14].
  • Tailor prevention: Different genetic findings can clarify your vulnerability to specific pathogens (bacteria, viruses, or fungi). This helps your doctor customize preventative antibiotics, antifungals, or specific vaccine recommendations, rather than relying on routine treatments [15][16].
  • Guide monitoring: Certain genes are linked to non-infectious complications, such as a higher risk for autoimmune diseases, inflammation, or specific cancers. A genetic result helps determine if you need specialized surveillance, though it does not mean these complications are inevitable [17][18].
  • Inform your family: A genetic diagnosis can help a genetic counselor determine if relatives should be tested for the specific variant, and support reproductive planning [6][19]. Testing relatives, particularly children, is usually tailored to whether it provides an immediate medical benefit.

Common questions in this guide

Why can genetic testing be useful when standard immune tests are normal?
Blood and immune-function tests show how the immune system is working, but they may not reveal the genetic reason for an immune disorder. Some people with genetically defined inborn errors of immunity have normal or only slightly low antibody levels, so genetic testing may still be useful when symptoms or family history raise concern.
How do clinicians decide between a gene panel, exome, and genome testing?
The main options are a targeted panel of selected genes, whole exome sequencing (WES) of protein-coding DNA, and whole genome sequencing (WGS) of nearly all DNA. The choice depends on your symptoms, family history, and whether a particular condition is suspected; broader tests may find more possibilities but may also produce more uncertain results.
What does a negative genetic test mean for an immunodeficiency diagnosis?
A negative result means that test did not find a clear disease-causing change; it does not rule out primary immunodeficiency. Some tests miss complex changes, such as missing or extra DNA segments, so your doctor may recommend another test or recheck the data later.
How should I interpret a VUS on an immune disorder test?
A variant of uncertain significance (VUS) is a DNA change whose health effect is not known yet. It generally should not be used by itself to diagnose an immune disorder or change treatment, but it may be reinterpreted as more evidence becomes available.
Can a genetic result change my treatment or monitoring?
Finding a disease-causing variant can help your team choose targeted medicines for some disorders, such as JAK inhibitors, or consider a blood-forming stem cell transplant in selected severe cases. It can also guide infection prevention, vaccine decisions, and monitoring for autoimmune disease, inflammation, or certain cancers.
Could testing reveal health risks unrelated to my immune system?
Before testing, a genetic counselor can discuss privacy, consent, and the possibility of learning about secondary findings—health risks unrelated to your immune system. You can often state in advance whether you want to receive those findings.
Does a primary immunodeficiency diagnosis mean my relatives should be tested?
A confirmed genetic cause can help a counselor decide whether biological relatives might benefit from testing and can support reproductive planning. Testing a child or other relative is usually considered when the result could provide an immediate medical benefit.

Related questions

What Do TREC and KREC Tests Screen For in Newborns? What Is the Difference Between GOF and LOF Mutations? Why Is Primary Immunodeficiency Now Called IEI? Explained What Is Life Expectancy With Primary Immunodeficiency? Why Are Live Vaccines Unsafe With Primary Immunodeficiency?
Show more
Primary vs Secondary Immunodeficiency: Key Differences What Are the Warning Signs of Primary Immunodeficiency? Can Primary Immunodeficiency Be Permanently Cured? Can Primary Immunodeficiency Be Diagnosed in Adults? How to Manage Primary Immunodeficiency Anxiety and Stress? Why Use Prophylactic Antibiotics in Primary Immunodeficiency? Why Do Primary Immunodeficiencies Cause Autoimmune Disease? What Are Long-Term Complications of Primary Immunodeficiency How Do IVIG and SCIG Differ for Primary Immunodeficiency? What is Common Variable Immunodeficiency (CVID) disease? What lifestyle changes help manage primary immunodeficiency? Why Does SCID Require Immediate Treatment for Babies?

Get notified when new evidence is published on Primary immunodeficiency.

We monitor PubMed for new peer-reviewed studies on this topic and email a short summary when something meaningful changes.

References

References (19)
  1. 1

    Peripheral-blood cytopenia, an early indicator of inborn errors of immunity.

    Cornelissen HM, Musekwa EM, Glashoff RH, et al.

    British journal of haematology 2022; (198(5)):875-886 doi:10.1111/bjh.18337.

    PMID: 35791731
  2. 2

    Diagnostic tests for primary immunodeficiency disorders: Classic and genetic testing.

    Klangkalya N, Fleisher TA, Rosenzweig SD

    Allergy and asthma proceedings 2024; (45(5)):355-363 doi:10.2500/aap.2024.45.240051.

    PMID: 39294902
  3. 3

    Diagnostic Modalities in Primary Immunodeficiency.

    Raymond LS, Leiding J, Forbes-Satter LR

    Clinical reviews in allergy & immunology 2022; (63(1)):90-98 doi:10.1007/s12016-022-08933-1.

    PMID: 35290615
  4. 4

    Australasian Society of Clinical Immunology and Allergy consensus statement on IEI molecular diagnosis.

    Yanes T, Cole T, Kane A, et al.

    Journal of human immunity 2026; (2(5)):e20250250 doi:10.70962/jhi.20250250.

    PMID: 42312137
  5. 5

    Genetic Causes, Clinical Features, and Survival of Underlying Inborn Errors of Immunity in Omani Patients: a Single-Center Study.

    Al-Tamemi S, Al-Zadjali S, Bruwer Z, et al.

    Journal of clinical immunology 2023; (43(2)):452-465 doi:10.1007/s10875-022-01394-3.

    PMID: 36324046
  6. 6

    Management change following NGS diagnosis of inborn errors of immunity: The Australasian experience.

    Swamy S, Shadur B, Hu H, et al.

    Journal of human immunity 2026; (2(6)) doi:10.70962/jhi.20260120.

    PMID: 42820864
  7. 7

    The utility of flow cytometry for the diagnosis of primary immunodeficiencies.

    Knight V

    International journal of laboratory hematology 2019; (41 Suppl 1()):63-72 doi:10.1111/ijlh.13010.

    PMID: 31069989
  8. 8

    Flow cytometry optimizing the diagnostic approach in inborn errors of immunity: experience from Egypt.

    Meshaal S, Ei Hawary R, Eldash A, et al.

    Allergy, asthma, and clinical immunology : official journal of the Canadian Society of Allergy and Clinical Immunology 2022; (18(1)):45 doi:10.1186/s13223-022-00688-w.

    PMID: 35655284
  9. 9

    Monogenic Inborn Errors of Immunity with impaired IgG response to polysaccharide antigens but normal IgG levels and normal IgG response to protein antigens.

    Fasshauer M, Dinges S, Staudacher O, et al.

    Frontiers in pediatrics 2024; (12()):1386959 doi:10.3389/fped.2024.1386959.

    PMID: 38933494
  10. 10

    Diagnostic yield of next-generation sequencing in suspect primary immunodeficiencies diseases: a systematic review and meta-analysis.

    Chen Y, Li D, Yin J, et al.

    Clinical and experimental medicine 2024; (24(1)):131 doi:10.1007/s10238-024-01392-2.

    PMID: 38890201
  11. 11

    Next-Generation Sequencing in the Field of Primary Immunodeficiencies: Current Yield, Challenges, and Future Perspectives.

    Vorsteveld EE, Hoischen A, van der Made CI

    Clinical reviews in allergy & immunology 2021; (61(2)):212-225 doi:10.1007/s12016-021-08838-5.

    PMID: 33666867
  12. 12

    Whole Genome Sequencing in 25 Families with Suspected Inborn Errors of Immunity: Diagnostic Yield and Clinical Relevance of Genome-wide Analysis.

    Lee JK, Jang JH, Kim DR, et al.

    Journal of clinical immunology 2025; (45(1)):170.

    PMID: 41275043
  13. 13

    Chromosomal microarray analysis supplements exome sequencing to diagnose children with suspected inborn errors of immunity.

    Beers BJ, Similuk MN, Ghosh R, et al.

    Frontiers in immunology 2023; (14()):1172004 doi:10.3389/fimmu.2023.1172004.

    PMID: 37215141
  14. 14

    JAK inhibitor treatment for inborn errors of JAK/STAT signaling: An ESID/EBMT-IEWP retrospective study.

    Fischer M, Olbrich P, Hadjadj J, et al.

    The Journal of allergy and clinical immunology 2024; (153(1)):275-286.e18 doi:10.1016/j.jaci.2023.10.018.

    PMID: 37935260
  15. 15

    How I Treat: Infections and inborn errors of immunity-Prevention, diagnosis, and treatment.

    Freeman AF, Thielen BK, Pozos TC

    Journal of human immunity 2026; (2(1)):e20250137 doi:10.70962/jhi.20250137.

    PMID: 41608118
  16. 16

    Inborn errors of immunity and invasive fungal infections: presentation and management.

    Paccoud O, Warris A, Puel A, Lanternier F

    Current opinion in infectious diseases 2024; (37(6)):464-473 doi:10.1097/QCO.0000000000001062.

    PMID: 39259685
  17. 17

    Management of the child with primary immunodeficiency.

    Lehman HK, Khaira A, Kaur S

    Current opinion in pediatrics 2025; (37(6)):606-612 doi:10.1097/MOP.0000000000001513.

    PMID: 41190402
  18. 18

    Malignancies in the context of Inborn errors of immunity: an immunologist's view.

    Genc Ozbay Z, Soyak Aytekin E, Esenboga S, Cagdas D

    Expert review of clinical immunology 2026; (22(2)):223-231 doi:10.1080/1744666X.2026.2633137.

    PMID: 41693687
  19. 19

    Deciphering the clinical and genetic spectrum of early-onset inborn errors of immunity in a Brazilian pediatric cohort.

    de Mattos L, Alves MM, Wegbecher NP, et al.

    Frontiers in immunology 2026; (17()):1839133 doi:10.3389/fimmu.2026.1839133.

    PMID: 42421943

This page is for informational purposes only and does not constitute medical advice. Discuss whether genetic testing is appropriate and how to interpret your results with your immunologist, physician, and genetic counselor.