title: Birth weight in newborn infants with different diabetes-associated HLA genotypes in three neighbouring countries: Finland, Estonia and Russian Karelia.
abstract: BACKGROUND
  Human leukocyte antigen (HLA) genotypes associated with increased risk for type 1 diabetes mellitus (T1D) have been reported to be associated with increased birth weight. We set out to investigate the association between HLA haplotypes conferring risk for T1D and birth weight and search for possible differences in the strength of these associations among populations with contrasting incidence of T1D.
  
  
  METHODS
  As a part of the EU-funded DIABIMMUNE study, genotyping for the HLA haplotypes associated with T1D was performed in 8369 newborn infants from Estonia, Finland and Russian Karelia. Infants born before 35 gestational weeks, from mothers with diabetes, and multiple pregnancies were excluded. Relative birth weight, expressed in standard deviation scores, was estimated for each gestational week, sex and country. The standard deviation scores were calculated internally using the actual population studied. According to their HLA haplotypes, participants were divided into risk groups, and the distribution of birth weight between quartiles was analysed.
  
  
  RESULTS
  We did not find any direct association between various HLA risk-associated genotypes (HLA DR3-DQ2/DR4-DQ8, DR3-DQ2/X or DR4-DQ8/X) and birth weight. We observed a significant relationship between increased relative birth weight and the protective HLA-DR2-DQ6 and DR13-DQ6 haplotypes. This association was significant only when these haplotypes were found together with the DR4-DQ8 haplotype.
  
  
  CONCLUSIONS
  The previously reported association between HLA-risk haplotypes for T1D and an increased birth weight was not confirmed. This suggests that the mechanisms behind the association between high birth weight and risk for T1D may be not directly HLA related.
authors.affiliation: Department of Pediatrics, University of Tartu, Tartu, Estonia. aleksandr.peet@kliinikum.ee
authors.forename: Aleksandr
authors.initials: A
authors.lastname: Peet
authors.forename: Pille
authors.initials: P
authors.lastname: Kool
authors.forename: Jorma
authors.initials: J
authors.lastname: Ilonen
authors.forename: Mikael
authors.initials: M
authors.lastname: Knip
authors.forename: Vallo
authors.initials: V
authors.lastname: Tillmann
mesh_terms: D000328:Adult; D001724:Birth Weight / Q000235:genetics*; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology / Q000235:genetics*; D004957:Estonia / Q000453:epidemiology; D005260:Female; D005387:Finland / Q000453:epidemiology; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006680:HLA Antigens / Q000235:genetics*; D006239:Haplotypes / Q000235:genetics*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D012426:Russia / Q000453:epidemiology; D055815:Young Adult
chemical_list: D006680:HLA Antigens