title: HLA-DQ genotypes - but not immune markers - differ by ethnicity in patients with childhood onset type 1 diabetes residing in Belgium.
abstract: The aim of this study was to compare genetic (HLA-DQ) and immune markers in a large population of type 1 diabetic (T1D) children and adolescents residing in the same environment, but of different ethnic origin: European Caucasians (EC), Moghrabin Caucasians (MC), Black Africans (BA) and of Mixed Origin (MO).
  
  
  
  Retrospective study, including 452 patients with T1D aged 0.1-17.5 yr at diagnosis recruited at the Diabetology Clinic of the University Children's Hospital Queen Fabiola from May 1995 to March 2013. HLA-DQ genotyping, diabetes-associated autoantibodies, organ-specific autoantibodies, and other markers of autoimmunity were studied.
  
  
  
  The proportion of the different ethnic groups was: 55% EC, 35% MC, 6% BA, and 4% MO. Between these four groups, there were no significant differences concerning age, hemoglobin A1c (HbA1c), presence of diabetic ketoacidosis, random C-peptide level at diagnosis and 2 yr later. The two most frequent haplotypes were DQA1*0501-DQB1*0201 and DQA1*0301-DQB1*0302 with a significant higher prevalence in MC and EC (p = 0.002 and 0.03, respectively). The high-risk heterozygous genotype DQA1*0301-DQB1*0302/DQA1*0501-DQB1*0201 was more frequent in EC than in MC, whereas the homozygous genotype DQA1*0501-DQB1*0201/DQA1*0501-DQB1*0201 was more prevalent in MC (p = 0.019). These susceptible genotypes were more frequent in youngest patients (p = 0.003). Diabetes-associated autoantibodies, organ-specific autoantibodies, and other immune markers did not statistically differ between ethnic groups.
  
  
  
  These observations in a large population of T1D children and adolescents of different ethnic groups residing in Belgium show significant differences in HLA-DQ status, but not in diabetes-associated autoantibodies, organ-specific autoantibodies, or other immune markers.
authors.affiliation: Diabetology Clinic, University Children's Hospital Queen Fabiola, Université Libre de Bruxelles (ULB), Brussels, Belgium.
authors.forename: Athanasia
authors.initials: A
authors.lastname: Stoupa
authors.affiliation: Diabetology Clinic, University Children's Hospital Queen Fabiola, Université Libre de Bruxelles (ULB), Brussels, Belgium.
authors.forename: Harry
authors.initials: H
authors.lastname: Dorchy
mesh_terms: D000293:Adolescent; D001323:Autoantibodies; D001530:Belgium / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000208:ethnology / Q000276:immunology*; D005260:Female; D006683:HLA-DQ Antigens / Q000235:genetics*; D006239:Haplotypes; D006801:Humans; D007223:Infant; D008297:Male; D012189:Retrospective Studies
chemical_list: D001323:Autoantibodies; D006683:HLA-DQ Antigens
keywords: antibodies; autoimmunity; ethnic groups; genotype; type 1 diabetes mellitus