Looking beyond GWAS: allele-specific transcription factor binding drives the association of GALNT2 to HDL-C plasma levels

Lipids Health Dis. 2016 Jan 27:15:18. doi: 10.1186/s12944-016-0183-x.


Background: Plasma levels of high-density lipoprotein cholesterol (HDL-C) have been associated to cardiovascular disease. The high heritability of HDL-C plasma levels has been an incentive for several genome wide association studies (GWASs) which identified, among others, variants in the first intron of the GALNT2 gene strongly associated to HDL-C levels. However, the lead GWAS SNP associated to HDL-C levels in this genomic region, rs4846914, is located outside of transcription factor (TF) binding sites defined by chromatin immunoprecipitation followed by DNA sequencing (ChIP-seq) experiments in the ENCODE project and is therefore unlikely to be functional. In this study we apply a bioinformatics approach which rely on the premise that ChIP-seq reads can identify allele specific binding of a TF at cell specific regulatory elements harboring allele specific SNPs (AS-SNPs). EMSA and luciferase assays were used to validate the allele specific binding and to test the enhancer activity of the regulatory element harboring the AS-SNP rs4846913 as well as the neighboring rs2144300 which are in high LD with rs4846914.

Findings: Using luciferase assays we found that rs4846913 and the neighboring rs2144300 displayed allele specific enhancer activity. We propose that an inhibitor binds preferentially to the rs4846913-C allele with an inhibitory boost from the synergistic binding of other TFs at the neighboring SNP rs2144300. These events influence the transcription level of GALNT2.

Conclusions: The results suggest that rs4846913 and rs2144300 drive the association to HDL-C plasma levels through an inhibitory regulation of GALNT2 rather than the reported lead GWAS SNP rs4846914.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles*
  • Cholesterol, HDL / blood*
  • Genome-Wide Association Study*
  • Hep G2 Cells
  • Humans
  • Linkage Disequilibrium / genetics
  • N-Acetylgalactosaminyltransferases / genetics*
  • Polymorphism, Single Nucleotide / genetics
  • Polypeptide N-acetylgalactosaminyltransferase
  • Protein Binding
  • Transcription Factors / metabolism*


  • Cholesterol, HDL
  • Transcription Factors
  • N-Acetylgalactosaminyltransferases