Primary immunodeficiency disorders — also called primary immune disorders or primary immunodeficiency — weaken the immune system, allowing infections and other health problems to occur more easily.

Many people with primary immunodeficiency are born missing some of the body's immune defenses or with the immune system not working properly, which leaves them more susceptible to germs that can cause infections.

So far, researchers have identified more than 300 forms of primary immunodeficiency disorders. Some forms are so mild they can go unnoticed until adulthood. Other types are severe enough that they're discovered soon after an affected baby is born.

Treatments can boost the immune system in many types of primary immunodeficiency disorders. Research is ongoing, leading to improved treatments and enhanced quality of life for people with the condition.

One of the most common signs of primary immunodeficiency is having infections that are more frequent, longer lasting or harder to treat than are the infections of someone with a typical immune system. You may also get infections that a person with a healthy immune system likely wouldn't get (opportunistic infections).

Signs and symptoms differ depending on the type of primary immunodeficiency disorder, and they vary from person to person.

Signs and symptoms of primary immunodeficiency can include:

• Frequent and recurrent pneumonia, bronchitis, sinus infections, ear infections, meningitis or skin infections
• Inflammation and infection of internal organs
• Blood disorders, such as low platelet count or anemia
• Digestive problems, such as cramping, loss of appetite, nausea and diarrhea
• Delayed growth and development
• Autoimmune disorders, such as lupus, rheumatoid arthritis or type 1 diabetes

If you or your child has frequent, recurrent or severe infections or infections that don't respond to treatments, talk to your health care provider. Early diagnosis and treatment of primary immune deficiencies can prevent infections that can cause long-term problems.

Many primary immunodeficiency disorders are inherited — passed down from one or both parents. Problems in the genetic code that acts as a blueprint for producing the cells of the body (DNA) cause many of these immune system defects.

There are more than 300 types of primary immunodeficiency disorders, and researchers continue to identify more. They can be broadly classified into six groups based on the part of the immune system that's affected:

• B cell (antibody) deficiencies
• T cell deficiencies
• Combination B and T cell deficiencies
• Defective phagocytes
• Complement deficiencies
• Unknown (idiopathic)

The only known risk factor is having a family history of a primary immune deficiency disorder, which increases your risk of having the condition.

If you have a type of primary immune deficiency disorder, you might want to seek genetic counseling if you plan to have a family.

Complications caused by a primary immunodeficiency disorder vary depending on what type you have. They can include:

• Recurrent infections
• Autoimmune disorders
• Damage to the heart, lungs, nervous system or digestive tract
• Slowed growth
• Increased risk of cancer
• Death from serious infection

Because primary immune disorders are caused by genetic changes, there's no way to prevent them. But when you or your child has a weakened immune system, you can take steps to prevent infections:

• Practice good hygiene. Wash your hands with mild soap after using the toilet and before eating.
• Take care of your teeth. Brush your teeth at least twice a day.
• Eat right. A healthy, balanced diet can help prevent infections.
• Be physically active. Staying fit is important to your overall health. Ask your doctor what activities are appropriate for you.
• Get enough sleep. Try to go to sleep and get up at the same time daily, and get the same number of hours of sleep every night.
• Manage stress. Some studies suggest that stress can hamper your immune system. Keep stress in check with massage, meditation, yoga, biofeedback or hobbies. Find what works for you.
• Avoid exposure. Stay away from people with colds or other infections and avoid crowds.
• Ask your doctor about vaccinations. Find out which ones you should have.

Your doctor will ask about your history of illnesses and whether any close relatives have an inherited immune system disorder. Your doctor will also perform a physical examination.

Tests used to diagnose an immune disorder include:

• Blood tests. Blood tests can determine if you have typical levels of infection-fighting proteins (immunoglobulins) in your blood and measure the levels of blood cells and immune system cells. Having numbers of certain cells in your blood that are outside of the standard range can indicate an immune system defect.

  Blood tests can also determine if your immune system is responding properly and producing proteins that identify and kill foreign invaders such as bacteria or viruses (antibodies).

• Prenatal testing. Parents who have a child with a primary immunodeficiency disorder might want to be tested for certain immunodeficiency disorders during future pregnancies. Samples of the amniotic fluid, blood or cells from the tissue that will become the placenta (chorion) are tested for problems.

  In some cases, DNA testing is done to check for a genetic defect. Test results make it possible to prepare for treatment soon after birth, if necessary.

Treatments for primary immunodeficiency involve preventing and treating infections, boosting the immune system, and treating the underlying cause of the immune problem. In some cases, primary immune disorders are linked to a serious illness, such as an autoimmune disorder or cancer, which also needs to be treated.

Managing infections

• Treating infections. Infections require rapid and aggressive treatment with antibiotics. Treatment might require a longer course of antibiotics than is usually prescribed. Infections that don't respond may require hospitalization and intravenous (IV) antibiotics.
• Preventing infections. Some people need long-term antibiotics to prevent respiratory infections and permanent damage to the lungs and ears. Children with primary immunodeficiency might not be able to have vaccines containing live viruses, such as oral polio and measles-mumps-rubella.
• Immunoglobulin therapy. Immunoglobulin consists of antibody proteins needed for the immune system to fight infections. It can either be injected into a vein through an IV line or inserted underneath the skin (subcutaneous infusion). IV treatment is needed every few weeks, and subcutaneous infusion is needed once or twice a week.

Treatment to reinstitute the immune system

• Stem cell transplantation. Stem cell transplantation offers a permanent cure for several forms of life-threatening immunodeficiency. Normal stem cells are transferred to the person with immunodeficiency, which results in a typically functioning immune system. Stem cells can be harvested through bone marrow, or they can be obtained from a placenta at birth (cord blood banking).

  The stem cell donor — usually a parent or other close relative — must have body tissues that are a close biological match to those of the person with primary immunodeficiency. Even with a good match, however, stem cell transplants don't always work.

  The treatment often requires that functioning immune cells be destroyed using chemotherapy or radiation before the transplants, leaving the transplant recipient temporarily even more vulnerable to infection.

• Gene therapy. This type of treatment involves taking stem cells from the person with primary immunodeficiency, correcting the gene in the cells and then returning the corrected stem cells back to the person via an intravenous infusion. With gene therapy, there is no need to find a suitable donor, as the person's own cells are used. Currently, this treatment is used to treat only a few primary immunodeficiencies, but clinical trials are underway for many other types.

Depending on the type of disorder, treatment may involve other therapies, including enzyme replacement therapy or transplantation of the thymus, an organ located behind the breastbone (sternum) that produces T cells.

Most people with primary immunodeficiency can go to school and work like everyone else. Still, you might feel as if no one understands what it's like to live with the constant threat of infections. Talking to someone who faces similar challenges may help.

Ask your doctor if there are support groups in the area for people with primary immunodeficiency or for parents of children with the disease. The Immune Deficiency Foundation has a peer support program as well as information on living with primary immunodeficiency.

You'll likely start by seeing your family doctor or primary doctor. You might then be referred to a doctor who specializes in disorders of the immune system (immunologist).

Here's some information to help you get ready for your appointment.

What you can do

• Write down symptoms, including any that may seem unrelated to the reason for your appointment, and when they began.
• Bring copies of records from hospitalizations and medical test results, including X-rays, blood test results and culture findings.
• Ask family members about the family medical history, including whether anyone was diagnosed with primary immunodeficiency, or if your family has babies or children who died of unknown causes.
• Make a list of medications, vitamins and supplements you or your child takes, including doses. If possible, list all of the antibiotic prescriptions and the dosages you or your child has taken for the past several months.
• Write down questions to ask your doctor.

Ask a family member or friend to come with you, if possible, to help you remember the information you're given.

For primary immunodeficiency, questions to ask your doctor include:

• What's the most likely cause of these symptoms?
• Are there other possible causes?
• What tests are needed? Do these tests require special preparation?
• What's the prognosis?
• What treatments are available, and which do you recommend?
• I have other health problems, how do I manage them together.
• Are there alternatives to the primary approach you're suggesting?
• Are there activity restrictions?
• Are there brochures or other printed material I can have? What websites do you recommend?

Don't hesitate to ask any other questions, as well.

What to expect from your doctor

Your doctor or your child's doctor is likely to ask you questions, including:

• When did the symptoms begin?
• Have symptoms been continuous or occasional?
• How many infections have you or your child had during the past year?
• How long do these infections usually last?
• Do antibiotics usually clear up the infection?
• How many times has your child taken antibiotics during the last year?