Common variable immunodeficiency (CVID) is one of the most frequently diagnosed primary immunodeficiencies (PIDs) characterised by antibody deficiency, poor responses to vaccination and an increased susceptibility to infections and complications due to immune dysregulation. The clinical diagnosis of CVID is an umbrella covering an immunologically and genetically heterogeneous group of diseases. To date, 22 disease‐causing genes have been associated with monogenic forms of CVID, encompassing 2–10% of reported cases. However, these genetic subtypes are now considered to account for distinct disease entities and have been removed from under the CVID umbrella. Furthermore, accumulating data suggest that the majority of CVID patients have a complex or multifactorial disorder, in which multiple genetic, epigenetic and/or environmental factors are involved. Genetic testing for monogenic causes should especially be performed in CVID patients with early onset of disease, noninfectious complications, a positive family history and/or consanguineous parents, since this could be important for genetic counselling, follow up and/or treatment decisions.
Key Concepts
CVID is a diagnosis of exclusion, encompassing a clinically, immunologically and genetically heterogeneous group of PID patients.
Monogenic defects have so far been reported in 2–10% of CVID patients.
The majority of CVID patients are believed to have a complex or multifactorial aetiology.
Patients in whom a monogenic cause is identified are no longer classified under CVID, but under separate disease entities (IUIS classification).
A monogenic cause of CVID is more probable in case of early onset of disease, complications of immune dysregulation, a positive family history and/or consanguinity.
Especially in CVID patients with early onset of disease and/or noninfectious complications, genetic workup should be performed to identify or exclude an underlying monogenic cause since this could be important for patient management decisions.