Unexpectedly High Prevalence of Common Variable Immunodeficiency in Finland

Area of Science:

• Immunology
• Epidemiology
• Genetics

Background:

• Common variable immunodeficiency (CVID) is the most frequent primary immunodeficiency, characterized by hypogammaglobulinemia and impaired vaccine response.
• Prevalence data for CVID varies significantly across different geographical regions and studies.
• Existing diagnostic criteria for CVID primarily focus on immunoglobulin levels and vaccine responsiveness.

Purpose of the Study:

• To determine the minimum prevalence of CVID in Southern Finland.
• To characterize the clinical and immunological phenotypes of CVID patients in the region.
• To investigate complications associated with CVID in the Finnish population.

Main Methods:

• A cross-sectional study was conducted involving adult CVID patients from three hospital districts in Southern and South-Eastern Finland (2007-2015).
• Diagnosis adhered to modified ESID/PAGID criteria for primary CVID, with specific thresholds for impaired antipolysaccharide responses to Pneumovax®.
• B cell phenotypes and CVID-associated complications were assessed in the patient cohort.

Main Results:

• The minimum adult CVID prevalence in Finland was calculated at 6.9 per 100,000 inhabitants (5.5 for 'probable CVID').
• Prevalence was highest in the Helsinki and Uusimaa district (7.7 per 100,000).
• Frequent complications were observed, including over one clinical phenotype in 73% of 'probable CVID' patients, gradual B cell loss in 16%, and confirmed association with large granular lymphocyte lymphoproliferation.

Conclusions:

• Finland exhibits the highest recorded CVID prevalence, potentially due to genetic isolation and founder effects.
• Further research into genetic variants contributing to the high prevalence in Finland is warranted.
• Enhanced physician awareness of CVID is crucial for earlier diagnosis and improved patient care outcomes.