title: Association analysis of proopiomelanocortin (POMC) haplotypes in type 1 diabetes in a UK population.
abstract: OBJECTIVE
  To assess the association of POMC haplotype-tagged single nucleotide polymorphisms (htSNPs) with the development of type 1 diabetes (T1D) in a Caucasian population.
  
  
  METHODS
  All exons, intron 1, and approximately 6-kb upstream and 3-kb downstream of the POMC gene were bidirectionally resequenced to identify DNA polymorphisms in 30 individuals. Allele frequencies were determined (60 chromosomes) and efficient htSNPs were selected using the htSNP2 programme. Genotyping was performed in 390 cases, 339 controls and 245 T1D parent-offspring trios, using Taqman, Sequenom and direct-sequencing technologies.
  
  
  RESULTS
  Thirteen polymorphisms (two novel) with a minor allele frequency greater than 1% were identified. Six POMC htSNPs (rs3754863 G>A, ss161151662 A>G, rs3754860 C>T, rs1009388 G>C, rs3769671 A>C, rs1042571 G>A) were identified. Allele and haplotype frequencies were similar between case and control groups (P>0.60 by permutation test), and assessment of allele transmission distortion from informative parents to affected offspring also failed to find any association. Stratification of these analyses for age-at-onset and HLA-DR risk group (DR3/DR4) revealed no significant associations. A haplotype block of 9.86-kb from rs3754863 to rs1042571 was identified, encompassing the POMC gene. Comparison of haplotype frequencies identified the GGCGAG haplotype as protective against T1D in 12.9% of cases vs. 18.3% of controls: χ(2)=8.18, Pc=0.03 by permutation test.
  
  
  CONCLUSIONS
  The POMC SNP haplotype GGCGAG may have a protective effect against T1D in the UK population. However, this finding needs to be replicated, and the cellular and molecular processes influenced by this POMC haplotype determined to fully appreciate its impact.
authors: Nephrology Research Group, Queen's University of Belfast, c/o Regional Genetics Centre, A-Floor Belfast City Hospital, Lisburn Road, Belfast, BT9 7AB, Northern Ireland, United Kingdom. rosalind.martin@qub.ac.uk
authors: R J L
authors: RJ
authors: Martin
authors: D A
authors: DA
authors: Savage
authors: D J
authors: DJ
authors: Carson
authors: A J
authors: AJ
authors: McKnight
authors: A P
authors: AP
authors: Maxwell
authors: C C
authors: CC
authors: Patterson
mesh_terms: D000293:Adolescent; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D002648:Child; D002675:Child, Preschool; D003922:Diabetes Mellitus, Type 1 / Q000453:epidemiology / Q000235:genetics*; D005260:Female; D006239:Haplotypes; D006801:Humans; D015810:Linkage Disequilibrium; D008297:Male; D009660:Northern Ireland / Q000453:epidemiology; D020641:Polymorphism, Single Nucleotide; D011333:Pro-Opiomelanocortin / Q000235:genetics*
chemical_list: D011333:Pro-Opiomelanocortin