Primary antibody deficiencies (PAD) [51 genes]

Primary antibody deficiencies (PAD) are the most common of all primary immune deficiencies (PID), and they are caused by genetic defects that disrupt B cell development, B cell differentiation, or class switch recombination, ultimately leading to defective antibody production and hypogammaglobulinemia. PADs include diseases such as agammaglobulinemia, hyper IgM syndrome, common variable immunodeficiency (CVID), and other selective antibody deficiencies (SAD).

• 1/500 (IgA deficiency)
• 1/25,000 (CVID)
• 1/200,000 (XLA)
• 1/500,000 (HIGM)
• 55% of all PID

• Differential diagnosis: cystic fibrosis, HIV, bronchiectasis, Crohn’s disease
• Genetic counseling
• Ig replacement (IVIG)
• Antibiotic prophylaxis
• Avoid corticosteroids in HIGM

The identification of a genetic defect responsible for the disease would allow a precise molecular diagnosis to be issued and makes it possible to provide genetic counseling to the patient and their family members. In some cases, detection of a genetic variant can help explore specific treatment options.

• Bacterial infections (respiratory, gastrointestinal, skin)
• Agamma/hypogammaglobulinemia
• Chronic inflammation, autoimmunity can be present
• Onset: infancy (XLA, HIGM); adulthood (CVID)