OR24 - Identifying Novel Genes and Biological Pathways for Apical Periodontitis

Abstract: Genome-wide association studies (GWAS) enable identification of genetic variants in genes playing a role in a given condition. In GWAS of apical periodontitis (AP), variants in/near 16 genes were identified as significantly associated with AP (p <5 x 10^-6). The role of these genes in AP, however, had not yet been described. To infer the relevance of GWAS-identified genes in AP, this study sought to investigate the mRNA expression of C5orf64-AS1, IRX1, LINC02114, LINC02487, LOC338694, MAK, MEPE, MPV17L, RALGAPB, RAP1GAP, STC1, SPP1 in AP tissues (n=24) in comparison to healthy periodontal ligaments as controls (n=4). Total RNA was extracted, complementary DNA (cDNA) synthesized, and used as a template in a reverse-transcription quantitative real-time polymerase chain reaction for messenger RNA expression analysis of target genes. Primer sequences were designed using Primer3. Reactions were run in triplicates in a QuantStudio instrument using SYBR Green chemistry. Negative control reactions without cDNA were used. Expression levels of each target gene were normalized to GAPDH expression in each sample and analyzed using the 2-DDCt method. Statistical differences between groups were assessed using Student’s t-test, with p<.05 as a significant threshold. The expression of C5orf64-AS1, LINC02114, LINC02487, MAK, MEPE, MPV17L, RAP1GAP, STC1 was significantly higher in AP tissues compared to controls (p <.05), whereas IRX1 was significantly decreased in AP (p <.05). No differences were found for SPP1 and LOC338694 expression between groups (p>.05). Our results show the expression of novel genes and implicate novel biological pathways in AP.