Epigenome-Wide Association Study for All-Cause Mortality in a Cardiovascular Cohort Identifies Differential Methylation in Castor Zinc Finger 1 ( CASZ1 ).

Background DNA methylation is implicated in many chronic diseases and may contribute to mortality. Therefore, we conducted an epigenome-wide association study (EWAS) for all-cause mortality with whole-transcriptome data in a cardiovascular cohort (CATHGEN [Catheterization Genetics]). Methods and Results Cases were participants with mortality≥7 days postcatheterization whereas controls were alive with≥2 years of follow-up. The Illumina Human Methylation 450K and EPIC arrays (Illumina, San Diego, CA) were used for the discovery and validation sets, respectively. A linear model approach with empirical Bayes estimators adjusted for confounders was used to assess difference in methylation (Δβ). In the discovery set (55 cases, 49 controls), 25 629 (6.5%) probes were differently methylated ( P <0.05). In the validation set (108 cases, 108 controls), 3 probes were differentially methylated with a false discovery rate-adjusted P <0.10: cg08215811 ( SLC4A9 ; log ₂ fold change=-0.14); cg17845532 ( MATK ; fold change=-0.26); and cg17944110 (castor zinc finger 1 [ CASZ1 ]; FC=0.26; P <0.0001; false discovery rate-adjusted P =0.046-0.080). Meta-analysis identified 6 probes (false discovery rate-adjusted P <0.05): the 3 above, cg20428720 (intergenic), cg17647904 ( NCOR2 ), and cg23198793 ( CAPN3 ). Messenger RNA expression of 2 MATK isoforms was lower in cases (fold change=-0.24 [ P =0.007] and fold change=-0.61 [ P =0.009]). The CASZ1 , NCOR2 , and CAPN3 transcripts did not show differential expression ( P >0.05); the SLC4A9 transcript did not pass quality control. The cg17944110 probe is located within a potential regulatory element; expression of predicted targets (using GeneHancer) of the regulatory element, UBIAD1 ( P =0.01) and CLSTN1 ( P =0.03), were lower in cases. Conclusions We identified 6 novel methylation sites associated with all-cause mortality. Methylation in CASZ1 may serve as a regulatory element associated with mortality in cardiovascular patients. Larger studies are necessary to confirm these observations.