Related Experiment Videos
Endothelial NO synthase polymorphisms and postural tachycardia syndrome
Emily M Garland1, Robert Winker, Scott M Williams
1Autonomic Dysfunction Center, Vanderbilt University, Nashville, TN 37232-2195, USA. emily.garland@vanderbilt.edu
Hypertension (Dallas, Tex. : 1979)
|October 6, 2005
Summary
Genetic variations in the nitric oxide synthase 3 gene may influence the risk and severity of Postural Tachycardia Syndrome (POTS). Lower frequencies of specific genotypes were observed in POTS patients, suggesting a role for nitric oxide in POTS development.
Area of Science:
- Cardiovascular Genetics
- Autonomic Nervous System Disorders
- Molecular Biology
Background:
- Postural Tachycardia Syndrome (POTS) is a complex disorder marked by excessive heart rate increase and symptoms of reduced blood flow to the brain upon standing.
- Endothelial nitric oxide (NO) synthase plays a crucial role in regulating blood flow, and its gene (NOS3) has known functional polymorphisms.
- Previous research suggests potential dysregulation of NO-mediated pathways in POTS, prompting investigation into genetic links.
Purpose of the Study:
- To investigate the association between genetic polymorphisms in the NOS3 gene (T-786C and E298D) and the risk of developing POTS.
- To determine if these NOS3 polymorphisms correlate with the severity of POTS symptoms, including orthostatic changes in heart rate and norepinephrine levels.
Main Methods:
- Genotyping of 136 POTS patients and 191 healthy controls for NOS3 promoter (T-786C) and exon 7 (E298D) polymorphisms.
- Orthostatic testing involving measurements of blood pressure, heart rate, and plasma norepinephrine in supine and upright positions.
- Statistical analysis, including odds ratios and confidence intervals, to compare genotype frequencies and correlate genotypes with physiological responses.
Main Results:
- Significantly lower frequencies of the -786CC and 298DD genotypes were found in POTS patients compared to controls (P=0.001 and P=0.033, respectively).
- Patients with the -786CC genotype, particularly when combined with 298EE or 298ED genotypes, exhibited the most pronounced changes in heart rate and plasma norepinephrine upon standing.
- These findings suggest a protective effect of certain NOS3 genotypes against POTS development and a link to symptom severity.
Conclusions:
- The study indicates that nitric oxide synthase 3 gene variants may influence susceptibility to Postural Tachycardia Syndrome.
- Specific NOS3 genotypes are associated with altered autonomic responses to standing, contributing to POTS pathophysiology.
- Further research into NO-mediated mechanisms could offer new therapeutic targets for POTS.