What Is Primary Immunodeficiency? 10 Key Facts To Know

Primary immunodeficiency (PI), also called inborn errors of immunity (IEI), is a group of lifelong conditions that affect how the immune system works. Normally, your immune system protects your body by fighting off infections, helping heal injuries, and removing cells that could become harmful, like cancer cells. When part of the immune system isn’t working the way it should, it’s easier to get sick and harder to recover.

If you or a loved one has been diagnosed with primary immunodeficiency, you probably have a lot of questions. This article will help you understand the basics of what primary immunodeficiency is, what causes it, and how it’s treated.

1. ‘Inborn Errors of Immunity’ Is the Updated Name for Primary Immunodeficiency

The official name for primary immunodeficiency was updated in 2017 to “inborn errors of immunity.” This term reflects that these conditions are genetic disorders — health problems caused by mutations (changes) in genes — that are present at birth and affect the immune system. People with IEI are more likely to get infections, but they may also have other immune-related problems such as autoimmune disorders, severe allergies, and an increased risk of certain types of cancer.

Although IEI is the official term, the condition is still often referred to as primary immunodeficiency, primary immunodeficiency disorder, or primary immune disorder.

2. Primary Immunodeficiency Happens When Part of the Immune System Is Missing or Doesn’t Work Properly

Your immune system is a network of organs, cells, proteins, and chemicals that act as your first line of defense against germs like bacteria, viruses, fungi, and parasites. It also recognizes and destroys abnormal cells (like cancer cells), toxins, and other foreign substances.

People with primary immunodeficiency have a genetic defect that results in one or more parts of the immune system not working properly. When your immune system doesn’t work well, it’s easier to develop infections and harder to fight them.

3. Primary Immunodeficiency Is Rare

Each type of primary immunodeficiency is rare on its own. However, when all the types are put together, they affect more people than you may think. It’s estimated that between 1 in 1,000 and 1 in 5,000 people are living with a form of primary immunodeficiency.

4. There Are More Than 500 Types of Primary Immunodeficiency

Primary immunodeficiency isn’t just one condition. It’s a group of more than 500 rare, chronic disorders that affect the immune system. Some forms affect just one type of immune cell or protein, while others affect two or more parts of the immune system.

About half of people diagnosed with primary immunodeficiency have B-cell deficiencies, such as:

• X-linked agammaglobulinemia (XLA)
• Common variable immunodeficiency (CVID)
• Selective IgA deficiency (SAD)

The most severe form of primary immunodeficiency is severe combined immunodeficiency (SCID). This type involves a combination of B- and T-cell deficiencies.

5. Primary Immunodeficiency Is Usually Inherited

Most types of primary immunodeficiency are caused by genetic mutations that can be passed down from parent to child. XLA and SCID are examples of inherited genetic mutations that cause primary immunodeficiency.

Some PI types aren’t always inherited in a predictable way. For example, CVID, SAD, and DiGeorge syndrome are sometimes caused by a combination of genetic and environmental factors.

Since most types of primary immunodeficiency run in families, it’s important to discuss your family history with your healthcare team. If you or a family member has PI, genetic counseling and testing may be recommended.

6. People With Primary Immunodeficiency May Get Sick More Often or Take Longer To Recover

In primary immunodeficiency, the body has a harder time fighting off infection, which can lead to infections that are more severe, don’t go away, or come back. In some cases, infections may be caused by microorganisms (germs) that don’t usually infect people with a healthy immune system. Symptoms of primary immunodeficiency often start in babies or children, but they can also develop in adults.

Infections can occur anywhere in the body. People with primary immunodeficiency are more likely to have infections, such as:

• Ear infections
• Sinusitis (sinus infection)
• Pneumonia and bronchitis (lung infection)
• Meningitis (infection of the brain or spinal cord)
• Skin infections
• Thrush (fungal infection)

Other possible symptoms of primary immunodeficiency include:

• Enlarged spleen
• Swollen lymph nodes
• Unexplained weight loss
• Poor or delayed growth and development in children
• Frequent diarrhea or other digestive issues
• Severe side effects from a live vaccine, such as the varicella (chickenpox) vaccine

7. Laboratory Tests Can Diagnose Primary Immunodeficiency

Laboratory tests on a blood sample can help healthcare providers learn if primary immunodeficiency is the cause of frequent or recurrent infections. A blood test can measure levels of antibodies, immune cells, and immune proteins (such as complement protein). Levels outside the normal range could indicate an immune system defect.

Genetic tests can identify genetic mutations linked to some types of primary immunodeficiency. In the past, genetic testing was available only in clinical trials, but now many tests are commercially available. Talk to your healthcare provider about the risks and benefits of genetic testing.

8. Newborns Are Screened for Severe Types of Primary Immunodeficiency

Newborn screening tests can help diagnose primary immunodeficiency before it causes symptoms. Healthcare providers take a small blood sample one to two days after a baby is born to test for several serious but treatable conditions, including SCID.

The SCID screening test checks for signs of low T-cell production. If testing finds the baby might have low or no T cells, they’ll need more testing to diagnose SCID.

Early diagnosis with newborn screening allows the family and healthcare team to take steps that can prevent severe infections and complications.

9. Treatments Can Help People With Primary Immunodeficiency Live an Active Life

Most types of primary immunodeficiency don’t yet have a cure. However, early diagnosis and treatment can help people with PI manage their symptoms, reduce infections, and live active lives. The best treatment option for you depends on your specific type of primary immunodeficiency.

Treatments To Prevent or Treat Infection

Some people with primary immunodeficiency may take antibiotics on a long-term basis to prevent bacterial infections. These drugs can also be used to treat an infection. While many antibiotics are available as pills you take by mouth, some infections may need to be treated with IV antibiotics in a hospital.

Immunoglobulin (Ig) replacement therapy can help prevent infections by replacing missing antibodies. Ig replacement therapy is considered the standard treatment for people with antibody deficiencies. This treatment fights infections by helping the immune system recognize and destroy bacteria and viruses.

Treatments That Address the Underlying Cause

In some types of primary immunodeficiency, treatment options can correct or replace part of the immune system that isn’t working properly. These include:

• Stem cell transplantation — A procedure that replaces defective immune cells with healthy stem cells from a donor
• Gene therapy — A treatment that adds or fixes the faulty gene to help the immune system work properly
• Enzyme replacement therapy — A treatment that provides a missing or defective enzyme to support normal immune function
• Thymus transplantation — A surgery to implant donated thymus tissue to support healthy T-cell development

10. People With Primary Immunodeficiency Must Take Steps To Prevent Infection

People with primary immunodeficiency have a higher risk of infections than people with a healthy immune system. Preventing infections is an important part of living with PI. To help prevent infections, you should:

• Wash your hands properly.
• Get regular exercise.
• Eat a healthy diet.
• Get enough sleep.
• Take care of your teeth.
• Avoid crowds.
• Avoid people who are sick.
• Stay up to date on vaccinations that are safe for you.

Find Your Team

On myPIteam, people share their experiences with primary immunodeficiency disorders, get advice, and find support from others who understand.

Have you or a loved one been diagnosed with primary immunodeficiency? What questions do you have about your diagnosis or treatment? Let others know in the comments below.