Epigenomewide Association Study of Monozygotic Twins Reveals That Serum Uric Acid Influences DNA Methylation

Hyperuricemia is a common metabolic disorder and has become a global health concern. This study investigated the association between DNA methylation (DNAm) and serum uric acid (SUA) by conducting an epigenomewide association study (EWAS) in Chinese monozygotic (MZ) twins. Genomewide DNAm of 50 MZ twin pairs was profiled using the Infinium MethylationEPIC v2.0 BeadChip (935K). Generalized estimating equations (GEE) were used to examine the association between DNAm and SUA. Causal relationships between DNAm and SUA were assessed using ICE FALCON approach. Associations between mRNA expression and SUA were further assessed. Finally, candidate genes identified through epigenomewide association study (EWAS), causal inference, and gene expression analyses were validated in a longitudinal twin study. We identified 70 CpGs, mapping to genes such as DOK6 and NGLY1, significantly associated with SUA (Bonferroni correction p < 5.8 × 10^-8). Causal analyses revealed one CpG with a causal effect of DNAm on SUA, 22 CpGs with causal effects of SUA on DNAm, and 33 CpGs showing bidirectional causality. Eleven genes displayed expression levels associated with SUA. DOK6, NGLY1, PKM, and SLC44A1 were selected as candidate genes, all of which showed unidirectional causal effect of SUA on DNAm. In the longitudinal analysis, baseline SUA levels (2012-13) were associated with subsequent DNAm levels in DOK6 and NGLY1 genes (2023-24). In conclusion, we found that SUA levels may influence DNAm variations, particularly at CpG loci within the DOK6 and NGLY1 genes. These findings provide key clues for future investigations into the mechanisms linking SUA with its epigenetic regulatory pathways.