908 - Preliminary Investigation of Differential Genomic DNA Methylation in Patients with Chronic Lower Back Pain in the Context of Oswestry Disability Index

Objectives:
Chronic lower back pain (cLBP) is a leading musculoskeletal problem with limited understanding of the contributions of genetics. Investigating epigenomics, such as DNA methylation, can help to better characterize cLBP in the context of clinical measures. The objective of this study was to identify differentially methylated regions (DMRs) in the context of low, medium, and high levels of disability as measured by the Oswestry Disability Index (ODI) in cLBP.

Design:
Whole blood was collected from 96 cLBP patients along with ODI data. DNA was extracted with the Qiagen Blood MiniPrep kit. Bisulfite conversions were completed Zymo EZ Bisulfite kits, followed by the Illumina Infinium Epic BeadChip 850k-probe assay. 11 samples were discarded due to low bisulfite-converted DNA integrity. ODI was calculated based on a 10 factor scale, with a maximum possible score of 100, with categorization of Low: 0-20 (n=19), Medium:21-40 (n=43), and High:41+ (n=23).

Data was processed through Genome Studio and R. To compare methylation, Beta values, the ratio of methylated probe intensity to overall intensity, were calculated at 850k genomic targets for each sample with p value for significance set to < 0.01.

Results:
Using t-test for statistical comparison, no difference was found in DNA methylation between the Low and Medium ODI groups and the Low and High groups. Comparing Medium-ODI and High-ODI, 73,711 probes were found to be differentially methylated, with 50,997 probes with increased methylation in the Medium-ODI group compared to the High-ODI group. The 5 most significant genes in these regions were: BRD2, associated with epilepsy; RNF5, which codes for ubiquitin ligase; SCAND3, a predicted oncogene; MDC1, associated with DNA damage repair; and AGPAT1, a MHC class III gene.

Conclusions:
In this preliminary study of methylation in the context of ODI, 5 genes were found to be differentially methylated between Medium-ODI and High-ODI groupings which warrant further investigation.