title: Epidemiology of Primary Immunodeficiency in Iceland.
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Immunology, Landspitali-The National University Hospital of Iceland, Hringbraut (building 14 at Eiriksgata), 101, Reykjavik, Iceland. bjornlud@lsh.is.
authors.forename: Bjorn R
authors.initials: BR
authors.lastname: Ludviksson
authors.affiliation: Department of Immunology, Landspitali-The National University Hospital of Iceland, Hringbraut (building 14 at Eiriksgata), 101, Reykjavik, Iceland.
authors.forename: Sigurveig T
authors.initials: ST
authors.lastname: Sigurdardottir
authors.affiliation: Department of Genetics and Molecular Medicine, Landspitali - The National University Hospital of Iceland, Hringbraut (building 7 at Baronstigur), 101, Reykjavik, Iceland.
authors.forename: Johann Heidar
authors.initials: JH
authors.lastname: Johannsson
authors.affiliation: Children's Hospital Iceland, Landspitali-University Hospital, 101, Reykjavík, Iceland.
authors.forename: Asgeir
authors.initials: A
authors.lastname: Haraldsson
authors.affiliation: Department of Immunology, Landspitali-The National University Hospital of Iceland, Hringbraut (building 14 at Eiriksgata), 101, Reykjavik, Iceland.
authors.forename: Thorgeir O
authors.initials: TO
authors.lastname: Hardarson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003165:Complement System Proteins / Q000172:deficiency; D004062:DiGeorge Syndrome / Q000453:epidemiology; D005260:Female; D006801:Humans; D007055:Iceland / Q000453:epidemiology; D007153:Immunologic Deficiency Syndromes / Q000175:diagnosis / Q000453:epidemiology* / Q000276:immunology; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D010586:Phagocytes / Q000276:immunology; D015995:Prevalence; D055815:Young Adult
chemical_list: D003165:Complement System Proteins
keywords: Primary immunodeficiencies; nation-wide study; prevalence; prevalence in Iceland