title: Does the relative risk for type 1 diabetes conferred by HLA-DQ, INS, and PTPN22 polymorphisms vary with maternal age, birth weight, or cesarean section?
abstract: OBJECTIVE
  Maternal age at birth, birth weight, and cesarean section has been associated with a weak but significant increase in risk of type 1 diabetes. The objective was to assess whether the relative risk for type 1 diabetes conferred by established susceptibility loci human leukocyte antigen (HLA)-DQ, INS, and PTPN22 differed depending on these perinatal factors.
  
  
  METHODS
  We employed a case-control study with 456 cases of type 1 diabetes diagnosed before 15 yr of age and 1377 population-based control children. HLA genotypes were divided into high to moderate risk (DQ8/DQ2, DQ8/DQ8, DQ8/X, DQ2/DQ2) vs. all other genotypes. Case-only analysis using logistic regression was used to test for significant interaction.
  
  
  RESULTS
  There was no significant difference in the relative risks conferred by HLA-DQ, INS, or PTPN22 by maternal age, birth weight, or mode of delivery, except the relative risk conferred by PTPN22 which was 2.11 [95% confidence interval (CI): 1.64-2.72] for those born vaginally and 0.99 (95% CI: 0.50-1.99) for those born by cesarean section [p(interaction) = 0.028].
  
  
  CONCLUSIONS
  The relative risks conferred by the three established susceptibility genes investigated here were independent of the perinatal factors, apart from a possible interaction between PTPN22 and mode of delivery.
authors.affiliation: Division of Epidemiology, Norwegian Institute of Public Health, Oslo, Norway. lars.christian.stene@fhi.no
authors.forename: Lars C
authors.initials: LC
authors.lastname: Stene
authors.forename: Kjersti S
authors.initials: KS
authors.lastname: Rønningen
authors.forename: Dag E
authors.initials: DE
authors.lastname: Undlien
authors.forename: Geir
authors.initials: G
authors.lastname: Joner
mesh_terms: D001724:Birth Weight / Q000235:genetics / Q000502:physiology*; D016022:Case-Control Studies; D002585:Cesarean Section; D002648:Child; D003922:Diabetes Mellitus, Type 1 / Q000209:etiology* / Q000235:genetics; D005260:Female; D020022:Genetic Predisposition to Disease / Q000209:etiology; D006683:HLA-DQ Antigens / Q000235:genetics*; D006801:Humans; D007231:Infant, Newborn; D007328:Insulin / Q000235:genetics*; D008297:Male; D008423:Maternal Age; D011110:Polymorphism, Genetic / Q000502:physiology; D011247:Pregnancy; D054596:Protein Tyrosine Phosphatase, Non-Receptor Type 22 / Q000235:genetics*; D012306:Risk
chemical_list: D006683:HLA-DQ Antigens; D007328:Insulin; C516765:PTPN22 protein, human; D054596:Protein Tyrosine Phosphatase, Non-Receptor Type 22