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Keshan disease (KSD), a potentially fatal cardiomyopathy, has very high incidence in some selenium-poor regions of China. KSD may be accompanied with a variety of arrhythmia, which is associated with mutations in the gene coding for cardiac voltage-gated sodium channel (SCN5A). The molecular mechanism of KSD is still largely obscure. We aimed to determine the association between the H558R polymorphism of SCN5A and KSD. We recruited 71 patients with KSD and 80 geographical region-matched control subjects in our study. Vital sign and electrocardiographic (ECG) measurements were performed for heart rate, systolic pressure, diastolic pressure, PR interval, QT interval, QRS duration, ST-T changes and complete right bundle branch block (CRBBB), and H558R polymorphism was genotyped using the polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) method and sequencing. A significant association was found between the H558R polymorphism of exon 12 and KSD. Allele C carriers had a decreased risk for KSD with an odds ratio of 0.332 [95% confidence interval (CI), 0.160-0.692] as well as for QRS prolongation in KSD patients with an odds ratio of 0.089 (95%CI, 0.022-0.361). Our results provide support to the association between H558R polymorphism and the decreased risk for KSD. H558R polymorphism might increase susceptibility to KSD, and SCN5A containing the polymorphism might be a predisposing gene for QRS prolongation.

Atrial fibrillation (AF) is one of the most common sustained cardiac arrhythmias and its prevalence is increasing worldwide in line with the growing elderly population. Many single nucleotide polymorphisms and mutations are associated with AF, including the common loss-of-function histidine-558-to-arginine (H558R) polymorphism of the human cardiac sodium channel, voltage-gated, type V, α subunit (encoded by the SCN5A gene). The H558R polymorphism results from the T-C transition in the SCN5A gene. This study recruited 135 patients with AF and 296 healthy controls to scan for and perform targeted genotyping of the H558R polymorphism of the SCN5A gene. Logistic regression analysis showed that the TC and CC genotypes (i.e. genotypes that result in the R558 polymorphism) were significantly associated with an increased risk of developing AF. The R558 polymorphism conferred an odds ratio for AF of 3.451 (95% confidence interval 1.718, 6.931). In conclusion, this study provided evidence for the role of the H558R polymorphism of the SCN5A gene in increasing the susceptibility to AF.

Subsequent to the publication of the 1977 edition of the NIOSH Registry of Toxic Effects of Chemical Substances (RTECS), several additions and changes were introduced that substantially improved the content and accessibility of the RTECS data file. Content additions included primary irritation data for both skin and eyes, in vitro mutagenicity data, and citations to toxicology review articles and to the Toxic Substances Control Act inventory. Also undertaken was a re-evolution of existing tumorigenic entries based on revised selection criteria. Accessibility to RTECS data has been facilitated by the introduction of on-line interactive computer searching, and the preparation and distribution of Computer Output Microfiche (COM-fiche) and magnetic tape copies of the file which supplement the annual publication.