Primary Immunodeficiency Disorders
The main function of the immune system is to protect against infections. When the immune system is compromised, immunodeficiency occurs, resulting in recurrent, unusual and/or difficult-to-treat infections. The most severe types of immunodeficiency allow germs that produce only mild illnesses in those with normal immune systems to cause serious, even deadly, infections. Many forms of primary immunodeficiency respond well to treatment. There are two categories of immunodeficiency disorders: primary and secondary. Primary immunodeficiency disorders (PIDD) have hereditary or genetic causes. Secondary immunodeficiency disorders result from environmental factors such as HIV infection, chemotherapy medications and malnutrition.
For many years, PIDD was believed to be relatively rare because only more extreme versions of the disorder were recognized. Today, because milder forms of PIDD have been identified, its diagnosis is not as uncommon. The most severe types of PIDD are often discovered early in childhood, while milder forms may remain undiagnosed until adolescence or even adulthood. Some variants never result in symptoms so may never be diagnosed.
Symptoms of Primary Immunodeficiency
There are dozens of different types of PIDD, and the symptoms they cause range from mild to severe. PIDD may stem from a malfunction in one or multiple parts of the immune system. People with PIDD are highly susceptible to infections, and may develop them more often, or have them last longer, than people without the disorder. Types of infections vary among individuals, but may include blood, ear, sinus and skin infections; pneumonia; bronchitis; and meningitis. Often, these infections do not adequately respond to typical treatments. PIDD can also lead to other conditions and issues, which, depending on the type of PIDD and the areas of the immune system that are weakened, may include:
- Developmental delays and slow growth in children
- Inflammation and damage to internal organs
- Autoimmune diseases
- Anemia or other problems of the blood
- Digestive difficulties
PIDD may also lead to complications including damage to the heart, lungs, nervous system or digestive tract, as well as an increased risk of certain cancers.
Causes of Primary Immunodeficiency
PIDD is usually genetics-based. A child often develops PIDD when he or she inherits certain defective or missing genetic material from the DNA passed down by a parent. Therefore, if there is a family history of PIDD, a child has a higher risk of being born with it.
Diagnosis of Primary Immunodeficiency
An allergist/immunologist is specifically trained to diagnose PIDD. To make an accurate diagnosis, a complete medical and family history, and a physical examination, are required. Information about the type and severity of a patient's symptoms, and how well she or he has responded to standard treatments, is assessed. It is essential to determine whether a patient's infections are caused by PIDD or by something else.
To confirm a suspected diagnosis of PIDD, a number of tests may be performed. Blood tests, by determining red-blood-cell, white-blood-cell and platelet counts, as well as immunoglobulin levels, provide significant information about immune-system functioning. Tests may also be run on the skin to elicit an immune system reaction. In addition, if there is a family history of PIDD, prenatal screenings may be recommended to learn whether a baby will be born with it. If so, in certain cases, treatment may begin in infancy.
Treatment of Primary Immunodeficiency
The most effective form of treatment varies based on the particular type of PIDD. Depending on the results of diagnostic testing, an allergist/immunologist develops and coordinates a treatment plan for the specific PIDD. Steps are taken to strengthen the immune system as much as possible, prevent infections from developing, and clear up any infections that are already present. Treatment may include antibiotics, immunoglobulin replacement or bone-marrow transplant.