Epidemiology of Primary Immunodeficiency in Iceland.

Purpose: Primary immunodeficiencies (PID) are rare heterogeneous diseases. Little is known about the prevalence of PID in Iceland and no national registry exists. The aim of the study was to describe the epidemiology of PID in Iceland.

Methods: Using The European Society's for Immunodeficiencies (ESID) criteria for PID, information about individuals with a known PID between 1990 and 2010 in Iceland were collected from inpatient registries of the National University Hospital of Iceland, the Department of Immunology and from clinical immunologists. Selective IgA deficiency, mannan binding lectin deficiency and secondary immunodeficiencies were excluded

Results: Sixty six individuals met the study criteria, 35 of them (53%) were females. Four patients died during the study period from PID- or treatment related complications and two moved abroad. In the beginning of 2011 there were 60 individuals living in Iceland with a known PID diagnosis meeting ESID's criteria. Estimated prevalence for PID in the Icelandic population of 318.452 habitants was 18.8 for 100.000 inhabitants. Predominantly antibody disorders comprised the largest category of PID in Iceland.

Conclusions: The prevalence of PID is high in Iceland compared to reports from other nations. Our patient data are easily accessible and a central laboratory measures the immune parameters. This high prevalence may indicate that PID is more common than generally recognized.