Primary Immunodeficiency Disease

Primary immunodeficiency disease (PID) refers to a group of mostly inherited conditions that involve impairment of the immune system and require ongoing management.1

Currently, more than 450 different genetic defects of PID have been identified, often presenting with hallmark recurrent and unusual infections.1,2

Also, some patients develop a higher susceptibility to noninfectious complications such as malignancies, autoimmune diseases and allergies.3


The actual prevalence remains unclear, but estimates range from 390,000 to 6 million people living with PID worldwide.4 In the U.S. alone, the prevalence is thought to be as high as 50.5 cases per 100,000 people.5 Although severe forms are more frequent in infancy and early childhood, the disease may not manifest until later in life in some cases.6


PIDs are broadly classified, but antibody deficiencies represent the most common form and are characterized by impaired antibody-producing components. In the U.S., antibody deficiencies account for more than half of all PID cases (63.4%).7 Due to their unique role in antibody production, defects in B cell development and function are the main cause of antibody deficiencies. However, defects in T cells and other immune cell types that contribute to B cell activity may also be present.8


PIDs are significantly underreported, and estimates suggest that 70-90% of patients are undiagnosed worldwide, largely because it is not top of mind.6 According to a U.S. survey (conducted in >1200 patients), the average time from symptom onset to diagnosis of all types of PID was 15 years.9 Diagnosing an antibody production deficit relies on a thorough medical and family history, physical examination and should be supplemented with diagnostic screening tests (e.g. complete blood count with differential white blood cell count, serum antibody levels, vaccine response) to help identify specific PID types.1,6

Navigating PID

The clinical presentation of PIDs is highly variable; however, recurrent sinopulmonary and gastrointestinal infections are particularly common.1,8,10,11 Therefore, the management approach is highly dependent on the type of defect and is largely focused on the prevention and treatment of infections, while more severe cases may require hematopoietic stem cell transplants.1,8 The mainstay treatment for primary B-cell immunodeficiencies, is replacement of serum IgG with either intravenous immunoglobulin (IVIG) or subcutaneous immunoglobulin (SCIG).1,7 If left untreated, PID can lead to hospitalizations, frequent days missed from work/school, prolonged antibiotic use, permanent organ damage or even death.10,12,13