Key result
The -786CC and 298DD genotypes of the endothelial NO synthase gene were associated with a significantly lower risk of postural tachycardia syndrome (OR 0.28; 95% CI 0.14-0.57; P=0.001 for -786CC).
Why the study?
Are endothelial NO synthase gene polymorphisms associated with the risk and severity of postural tachycardia syndrome (POTS)?
Case-Control (n=327)
Yes
Are endothelial NO synthase gene polymorphisms associated with the risk and severity of postural tachycardia syndrome (POTS)?
Specific endothelial NO synthase gene polymorphisms (-786CC and 298DD) are associated with a lower risk of developing POTS, suggesting NO plays a role in its pathogenesis.
Postural tachycardia syndrome (POTS) is a heterogeneous disorder characterized by an excessive rise in heart rate and symptoms consistent with cerebral hypoperfusion in the upright position. NO produced by endothelial NO synthase is a significant factor in the regulation of blood flow. Genetic polymorphisms in the promoter region (T-786C) and exon 7 (E298D) of the NO synthase isoform 3 gene affect enzyme activity and have been associated with a number of cardiovascular diseases. Because some findings in POTS suggest aberrant NO-mediated functions, we postulated that the variant genotypes of these polymorphisms may increase the risk of developing POTS and correlate with more severe symptoms. We genotyped 136 patients with POTS (mean age 32.2+/-9.9 years; 46 men and 90 women) from Nashville, Tenn, and Vienna, Austria, and compared them with 191 healthy volunteers (mean age 29.1+/-8.0 years; 127 men and 64 women). Participants also underwent orthostatic testing with blood pressure, heart rate, and plasma norepinephrine measurements while supine and upright. The frequencies of the -786CC and 298DD genotypes were significantly lower in patients with POTS than in control subjects (odds ratio [OR], 0.28; 95% confidence interval [CI], 0.14 to 0.57; P=0.001 for -786CC; and OR, 0.44; 95% CI, 0.21 to 0.91; P=0.033 for 298DD). According to 2-locus genotype analyses, patients with -786CC and 298EE or 298ED experienced the largest changes in heart rate and plasma norepinephrine with standing. These results indicate that NO may influence the development of POTS and the severity of POTS symptoms.
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Garland et al. (2005) conducted a case-control in Postural tachycardia syndrome (POTS) (n=327). Endothelial NO synthase polymorphisms (-786CC and 298DD genotypes) vs. Healthy volunteers was evaluated on Frequency of the -786CC genotype (OR 0.28, 95% CI 0.14 to 0.57, p=0.001). The -786CC and 298DD genotypes of the endothelial NO synthase gene were associated with a significantly lower risk of postural tachycardia syndrome (OR 0.28; 95% CI 0.14-0.57; P=0.001 for -786CC).
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