Primary immunodeficiencies (PIDs), also referred to as inborn errors of immunity (IEI), are a group of genetic conditions that affect the development and/or function of the body’s immune system.¹ The immune system is involved in fighting against and protecting the body from infections. In PIDs, the immune system is compromised (weakened, absent or unstable), causing individuals to be more vulnerable (susceptible) to infections, autoimmunity, inflammation and cancers.^1,2 The symptoms of PIDs may appear during childhood or in adulthood.

In PIDs, the defects that affect the immune system are usually inherited (passed down from parents). PIDs differ from secondary immunodeficiencies, which are usually acquired and caused by other external factors such as infection, malnutrition, immunosuppressive medical therapies and cancer.²

There are currently over 500 different PIDs,¹ with more PIDs continually being recognised over time.³ PIDs have been categorised into ten categories:³

• Combined immunodeficiencies
• Combined immunodeficiencies with syndromic features
• Predominantly antibody deficiencies
• Diseases of immune dysregulation
• Congenital defects of phagocytes
• Defects in intrinsic and innate immunity
• Autoinflammatory diseases
• Complement deficiencies
• Bone marrow failure
• Phenocopies of inborn errors of immunity

It has been reported that a significant proportion of  individuals are undiagnosed until adulthood.²

Synonyms: primary immunodeficiency disorder, PI, PIDs, inborn errors of immunity (IEI).^1-3

ORPHA:101997 Primary immunodeficiency

ICD-11: Primary immunodeficiencies

Universal rare disease classifications provide a common language for recording, reporting and monitoring diseases. Please visit the Rare Disease Classifications page for more information about these internationally recognised classifications.

There are a wide range of signs and symptoms for the different types of PIDs, and severity may vary.

Some common signs and symptoms of PIDs may include:^2,4

• recurrent infections that are unusually persistent, severe or resistant to treatment
• poor growth and failure to thrive in infants
• recurrent deep skin or organ abscesses (build-up of pus)
• persistent thrush
• skin rashes
• chronic diarrhea
• excessive inflammatory responses and autoimmunity

Individuals with PIDs are associated with a higher risk of autoimmune conditions and cancers.²

Please speak to your medical team to learn more about the symptoms and complications of PIDs.

Rare diseases are often serious and progressive, exhibiting a high degree of symptom complexity, leading to significant disability. Majority of the estimated two million Australians living with a rare disease meet the Australian Government’s definition for disability (in accordance to the Australian Public Service Commission and Australian Bureau of Statistics), and many experience severe and permanent disability impacts. If you or someone you care for is experiencing disability-related impacts from a rare condition, please speak with a health or disability professional for advice. Information about relevant disability support can be found at the RARE Portal’s Disability Support Information page.

PIDs are genetic conditions caused by disease-causing genetic changes (variants) leading to immune deficiency and dysregulation.² More than 400 different genetic variants have been identified to cause PIDs so far.

PIDs are usually inherited (passed down from parents). Different patterns of inheritance such as autosomal dominant, autosomal recessive and X-linked have been observed in different types of PIDs.²

More information about inheritance patterns can be found at:

• Immune Deficiencies Foundation Australia: Genetic Diagnosis of Primary Immunodeficiencies
• Centre for Genetics Education: Autosomal dominant inheritance
• Centre for Genetics Education: Autosomal recessive inheritance
• Centre for Genetics Education: X-linked inheritance

If you would like to learn more about the inheritance and impact of this condition, please ask your doctor for a referral to a genetic counsellor. Genetic counsellors are qualified allied health professionals who can provide information and support regarding genetic conditions and testing. More information about genetic counselling can be found at:

• Information on Genetic Services
• The National and State Services pages underneath the ‘Genetic Counselling’ sections listed

Diagnosis of PIDs may be made based on physical examination, family history, laboratory tests to look for presence of haematologic (blood) abnormalities that are indicative of PIDs and genetic testing.^1,2

The laboratory tests may include complete blood count (CBC) and blood smear, quantitative serum immunoglobulin tests, neutrophil function assays, assessment of specific antibody response and complement studies. Additional tests may be performed to rule out other conditions with similar symptoms, such as HIV tests, rheumatoid factor tests and cancer screening.⁵ Genetic testing may be performed in some circumstances, and is becoming increasingly available.

Severe combined immunodeficiency (SCID), which is a type of PID, is now being screened for in Australia’s newborn bloodspot screening (NBS) programme. More information can be found at Immune Deficiencies Foundation Australia: SCID Newborn Screening.

Please speak to your medical team to learn more about the available diagnostic pathways for the specific type of PIDs.

Treatment will depend on the type and severity of PIDs. These include:^1,4,6

• immunoglobulin replacement therapy (IRT) to restore and maintain sufficient immunoglobulin (antibodies) levels. IRT can be given as intravenous immunoglobulin (IVIg) or subcutaneous immunoglobulin (SCIg). More information about IRT can be found at National Blood Authority Australia: Immunoglobulin Therapy, and
  Australasian Society of Clinical Immunology and Allergy (ASCIA): Immunoglobulin Replacement Therapy Frequently Asked Questions.
• immunomodulatory drugs to increase or decrease immune function and reduce complications from infections, autoimmune diseases and/or other inflammatory conditions
• antibiotics, antifungals and antivirals medications to treat and prevent infection
• haematopoietic stem cell transplant (HSCT) such as bone marrow transplant, which may be curative for some types of PIDs, however may not be suitable for everyone

Early appropriate treatment can reduce the risk of infections and complications.^1,4,6

For individuals with PIDs, it may be important to discuss vaccination and immunisation with your medical team. More information about vaccination for individuals with PIDs can be found at:

• Australian Immunisation Handbook: Vaccination for people with inborn errors of immunity, including primary immunodeficiency

• Immune Deficiencies Foundation Australia: Vaccines and Primary Immunodeficiencies

Please speak to your medical team to learn more about the possible treatment or management options for your condition. Treatment will depend on an individual’s specific condition and symptoms. It is also important to stay connected to your medical team so that you can be made aware of any upcoming clinical trial opportunities.

Clinical care for rare diseases often involves a multidisciplinary team of medical, care and support professionals. Please note that the information provided here is as a guide and that RVA does not necessarily monitor or endorse specific clinics or health experts.

Healthcare professionals involved in the treatment of PIDs may include general practitioners (GP), paediatricians, clinical immunologists, immunology nurses, dentists, dietitians, genetic counsellors, occupational therapists, physiotherapists and psychologists.⁶ The need for different healthcare professionals may change over a person’s lifetime and extend beyond those listed here.

Australasian Society of Clinical Immunology and Allergy (ASCIA): Primary Immunodeficiency (PID) Clinical Update (2025) has information on diagnosis and management of PIDs.

Human Inborn Errors of Immunity: 2024 Update on the Classification from the International Union of Immunological Societies Expert Committee and The 2024 update of IUIS phenotypic classification of human inborn errors of immunity report on an updated classification for PIDs developed by international expert committee comprising paediatric and adult clinical immunologists, clinicians and researchers, including experts from Australia.

ASCIA Clinical Care Standard for Inborn Errors of Immunity/Primary Immune Deficiency (2025) includes guidelines and statements to improve health outcomes and quality of life for people with PIDs.

Individuals living with rare diseases may have complex medical issues and disabilities, which are not always visible. It is often useful to refer to their medical history as well as personal information such as a medical card, doctor’s letter, or if available, a rare disease passport, for relevant information.

It may be important to consider the following when managing individuals living with PIDs at emergency departments/services:

• prompt recognition and treatment of infections
• contacting an immunology specialist for suspected PIDs cases or if there are any concerns about known cases

There are specific considerations around participating in rare disease research, including clinical trials. It is important to be mindful of issues such as data privacy, research ethics, consent and differences in research regulations between Australia and other countries.

If you are interested in finding clinical trials for your condition, please visit the following websites; however, there may not be any clinical trials available:

• Australian Clinical Trials
• ClinicalTrials.gov

It is best to discuss your interest in any clinical trials with your medical team to determine suitability and eligibility.

Please note that RVA does not necessarily monitor or endorse each group/organisation’s operational governance and activities.

Australian Organisation:

Immune Deficiencies Foundation Australia (IDFA)

Website: https://www.idfa.org.au/

IDFA is a national not-for-profit and leading peak body offering education, advocacy and awareness for Australians living with primary or secondary immunodeficiencies.

Please note that RVA does not monitor or endorse each group/organisation’s operational governance and activities. When engaging with a group, please consider the information on the RARE Portal’s Finding Helpful Peer and Community Supports page.

PIDs vary between individuals, and each person’s experience is unique.

Please visit Immune Deficiencies Foundation Australia: Member Stories to read the personal stories of living with PIDs.

If you would like to share your personal story with RVA, please visit the Rare Voices Australia: Share Your Story page. RVA will consider your story for publishing on our website and inclusion on the RARE Portal.

Immune Deficiencies Foundation Australia: Community Events has information about peer support and community groups for people living with immunodeficiency.

Immune Deficiencies Foundation Australia: Member Toolkits has resources tailored for child, young adults, adults, carers and health professionals.

Immune Deficiencies Foundation Australia: Self-Advocacy Tools

Immune Deficiencies Foundation Australia: Immunodeficiencies and Applying for the NDIS

For information on available government and social services that provide support for individuals with a rare disease, please visit the National and State Services pages.

People living with a rare disease, including families and carers, often face unique challenges such as diagnostic delays, misdiagnoses, limited treatment options, and limited access to rare disease specialists and support. These challenges may impact people’s emotional wellbeing and quality of life. Many people find it helpful to seek mental health and wellbeing support to cope with ongoing stress and uncertainty. Connecting with people who have shared experiences through a support group may also be helpful. Information about relevant mental health and wellbeing support can be found at:

• Mental Health and Wellbeing Support for Australians Living with a Rare Disease
• The National and State Services pages underneath the ‘Mental Health’ sections listed

Further information on PIDs can be found at:

• Immune Deficiencies Foundation Australia: Publications
• Australasian Society of Clinical Immunology and Allergy (ASCIA): Immunodeficiencies
• International Patient Organisation for Primary Immunodeficiencies (IPOPI): What are Primary Immunodeficiencies (PIDs)?

Australasian Society of Clinical Immunology and Allergy (ASCIA): Resources for health professionals – Immunodeficiency and Autoimmunity

ASCIA Immunodeficiency Strategy for Australia and New Zealand

Orphanet: Primary immunodeficiency

Genetic testing in patients with a suspected primary immunodeficiency or autoinflammatory syndrome

This page has been co-developed by Rare Voices Australia (RVA)’s RARE Portal team in consultation with Immune Deficiencies Foundation Australia (IDFA).

If you are aware of any additional information that may benefit stakeholders with an interest in this page, or if you notice any broken links or inaccurate information, please let us know via the Contribute page.