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. 2012 Jun 12:8:31.
doi: 10.1186/1744-9081-8-31.

A genetic association study of DNA methylation levels in the DRD4 gene region finds associations with nearby SNPs

Sophia J Docherty  1 , Oliver Sp Davis, Claire Ma Haworth, Robert Plomin, Ursula D'Souza, Jonathan Mill
Affiliations

A genetic association study of DNA methylation levels in the DRD4 gene region finds associations with nearby SNPs

Sophia J Docherty et al. Behav Brain Funct. .

Abstract

Background: Dopamine receptor D4(DRD4) polymorphisms have been associated with a number of psychiatric disorders, but little is known about the mechanism of these associations. DNA methylation is linked to the regulation of gene expression and plays a vital role in normal cellular function, with abnormal DNA methylation patterns implicated in a range of disorders. Recent evidence suggests DNA methylation can be influenced by cis-acting DNA sequence variation, that is, DNA sequence variation located nearby on the same chromosome.

Methods: To investigate the potential influence of cis-acting genetic elements within DRD4, we analysed DRD4 promoter DNA methylation levels in the transformed lymphoblastoid cell-line DNA of 89 individuals (from 30 family-trios). Five SNPs located +/- 10kb of the promoter region were interrogated for associations with DNA methylation levels.

Results: Four significant SNP associations were found with DNA methylation (rs3758653, rs752306, rs11246228 and rs936465). The associations of rs3758653 and rs936465 with DNA methylation were tested and nominally replicated (p-value < 0.05) in post-mortem brain tissue from an independent sample (N = 18). Interestingly, the DNA methylation patterns observed in post-mortem brain tissue were similar to those observed in transformed lymphoblastoid cell line DNA.

Conclusions: The link reported between DNA sequence and DNA methylation offers a possible functional role to seemingly non-functional SNP associations. DRD4 has been implicated in several psychiatric disease phenotypes and our results shed light upon the possible mode of action of SNP associations in this region.

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Figures

Figure 1
Figure 1
Positional overview of DRD4 region investigated for SNP associations with DNA methylation. White boxes = exons; Black box = region assessed for DNA methylation. Diagram created using data from UCSC ( http://genome.ucsc.edu/) and HapMap ( http://hapmap.ncbi.nlm.nih.gov/).
Figure 2
Figure 2
Significant SNP associations with average DNA methylation levels in the DRD4 gene region. Average percentage DNA methylation plotted by genotype at associated SNPs. Thick black lines represent group mean. Whiskers mark one standard deviation from the mean. As our sample contained only one TT homozygote at rs752306, we collapsed it into the heterozygote groups for analysis.
Figure 3
Figure 3
LD pattern (a = D’, b = r2 ) across 9 SNPs associated with average DNA methylation in the DRD4 gene region.
Figure 4
Figure 4
Average percentage DNA methylation across CpG sites in the DRD4 region by genotype groups at 4 associated SNPs. Error bars denote standard deviation. * = significant associations at the p < 0.05 level. Though association analyses were conducted on arcsine transformed data, the true proportion of methylation observed is plotted here. The one homozygous TT subject at rs752306 within our sample was collapsed with the heterozygote group in association analyses.
Figure 5
Figure 5
Correlation across CpG sites within the DRD4 region. Colours represent Pearson’s product–moment correlations between DNA methylation levels at DRD4-association CpG sites. Colour key is provided to the right of the plot.
Figure 6
Figure 6
DRD4 percentage DNA methylation levels in CEPH transformed lymphoblastoid cell lines and post-mortem Singular Frontal Gyrus tissue (SFG). a) Average DRD4 DNA methylation levels plotted by rs3802971 genotype b) DNA methylation levels across individual DRD4 CpG sites plotted by rs3802971 genotype group. * = significant associations at the p < 0.05 level. Though arcsine transformed data were used in analyses, the true proportion of DNA methylation observed is plotted here. The one heterozygous subject in the post-mortem brain tissue sample was combined with the TT homozygotes for analyses.
Figure 7
Figure 7
DRD4 percentage DNA methylation levels in CEPH transformed lymphoblastoid cell lines and post-mortem Mid-brain and Singular Temporal Gyrus tissue (STG). a) Average DRD4 DNA methylation levels plotted by rs936465 genotype b) DNA methylation levels across individual DRD4 CpG sites plotted by rs936465 genotype group. * = significant associations at the p < 0.05 level. Though arcsine transformed data were used in analyses, the true proportion of DNA methylation observed is plotted here. The one subject with available mid-brain DNA methylation data who was GG homozygous at rs936465 was combined with the heterozygotes for analyses.
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References

    1. Van Tol HH, Bunzow JR, Guan HC, Sunahara RK, Seeman P, Niznik HB, Civelli O. Cloning of the gene for a human dopamine D4 receptor with high affinity for the antipsychotic clozapine. Nature. 1991;350:610–614. doi: 10.1038/350610a0. - DOI - PubMed
    1. Faraone SV, Mick E. Molecular genetics of attention deficit hyperactivity disorder. Psychiatr Clin N Am. 2010;33:159–180. doi: 10.1016/j.psc.2009.12.004. - DOI - PMC - PubMed
    1. Li D, Sham PC, Owen MJ, He L. Meta-analysis shows significant association between dopamine system genes and attention deficit hyperactivity disorder (ADHD) Hum Mol Genet. 2006;15:2276–2284. doi: 10.1093/hmg/ddl152. - DOI - PubMed
    1. Munaf MR, Yalcin B, Willis-Owen SA, Flint J. Association of the dopamine D4 receptor (DRD4) gene and approach-related personality traits: meta-analysis and new data. Biol Psychiatry. 2008;63:197–206. doi: 10.1016/j.biopsych.2007.04.006. - DOI - PubMed
    1. Lasky-Su J, Lange C, Biederman J, Tsuang M, Doyle AE, Smoller JW, Laird N, Faraone S. Family-based association analysis of a statistically derived quantitative traits for ADHD reveal an association in DRD4 with inattentive symptoms in ADHD individuals. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics. 2008;147:100–106. - PubMed

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