Risk stratification of Brugada syndrome (BrS) remains controversial and the majority of patients with BrS have no genetic explanation. We investigated relationships between genotypes of 3 single-nucle Show more
Risk stratification of Brugada syndrome (BrS) remains controversial and the majority of patients with BrS have no genetic explanation. We investigated relationships between genotypes of 3 single-nucleotide polymorphisms reported in a recent genome-wide association study and BrS phenotypes. SCN10A (rs10428132), SCN5A (rs11708996), and downstream from HEY2 (rs9388451) single-nucleotide polymorphisms were genotyped and compared between 95 Japanese patients with BrS and 1978 controls. Relationships between the single-nucleotide polymorphisms and clinical characteristics, 12-lead ECG findings, signal-averaged ECG findings, and electrophysiological parameters were also examined in patients with BrS. Both rs10428132 and rs9388451 were significantly associated with BrS (P=2.7×10(-14); odds ratio, 3.0; P=9.2×10(-4); odds ratio, 1.7, respectively). Interestingly, the HEY2 risk allele C was less frequent in BrS patients with ventricular fibrillation than in those without (59% versus 74%; P=4.1×10(-2); odds ratio, 0.5). A significant linear correlation was found between HEY2 genotypes and QTc interval (CC: 422±27 ms; CT: 408±21 ms; and TT: 381±27 ms; P= 4.0×10(-4)). The HEY2 mRNA expression level in the right ventricular specimens from patients with BrS (n=20) was significantly lower in patients with CC genotype than the other genotypes (P=0.04). Additionally, during 63±28 months follow-up periods after implantable cardioverter defibrillator implantation (n=90), Kaplan-Meier event-free survival curves revealed that the cumulative rate of ventricular fibrillation events was significantly lower in cases with HEY2 CC genotype (P=0.04). Our findings suggest that HEY2 CC genotype may be a favorable prognostic marker for BrS, protectively acting to prevent ventricular fibrillation presumably by regulating the repolarization current. Show less
The apolipoprotein A5 gene (ApoA5) plays an important role in modulating triglyceride metabolism. Polymorphisms of ApoA5, including -1131T>C and c.553G>T (G185C), have been reported to correlate with Show more
The apolipoprotein A5 gene (ApoA5) plays an important role in modulating triglyceride metabolism. Polymorphisms of ApoA5, including -1131T>C and c.553G>T (G185C), have been reported to correlate with hypertriglyceridemia (HTG). In the present study the relationships of 5 single nucleotide polymorphisms, including the -1131T>C, c.56C>G, IVS3+476G>A, c.553G>T, and c.1259T>C polymorphisms of ApoA5, with HTG were investigated. The study group comprised 95 Japanese patients with HTG and 119 unrelated normolipidemic subjects. Frequencies of the C allele of -1131T>C (0.511) and the T allele of c.553G>T (0.205) in the hypertriglyceridemic patients were significantly higher than in the normolipidemic subjects (0.315 and 0.105, respectively). The c.56C>G (S19W) polymorphism was not observed, and the other 4 polymorphic sites were in strong linkage disequilibrium. Five of the 8 detected haplotypes with the C allele of -1131T>C correlated with HTG. Promoter activities of ApoA5, including that with the -1131T>C polymorphism, were estimated using a luciferase assay. Analysis of ApoA5 promoters showed that the -1131T>C polymorphism alone had no effect. Comparison of expression of mutant G185C and wild-type ApoA5-green fluorescent protein (GFP) in HepG2 cells showed that ApoA5-GFP was abundant in punctate endosome-like structures, and ApoA5 (G185C)-GFP expression resembled that of the wild type. The -1131T>C and c.553G>T (G185C) polymorphisms correlated with HTG in this Japanese population, but neither polymorphism directly affected ApoA5 expression. Show less