Genetics and Cardiovascular Reactivity in Young Twins

NCT ID: NCT00083850

Last Updated: 2016-07-29

Basic Information

• Recruitment Status: COMPLETED
• Study Classification: OBSERVATIONAL
• Study Start Date: 2004-06-30
• Study Completion Date: 2007-05-31

Brief Summary

To evaluate the effects of genetic variants in all of the nine adrenergic receptor subtype genes, alone or in combination, on cardiovascular reactivity and other quantitative cardiovascular traits in a population of 1048 healthy young twins.

Detailed Description

BACKGROUND:

Several studies have shown that cardiovascular reactivity (CVR) to acute laboratory stress is a stable and heritable trait and predictive of future blood pressure (BP) levels and essential hypertension (EH). The sympathetic nervous system (SNS) has a major role in BP regulation and adrenergic receptor subtypes mediate BP responses to acute challenges. As such, our hypothesis is that individual differences in CVR are partly determined by variation in genes encoding for adrenergic receptors mediating the sympathoadrenal response to stress. There is increasing evidence that this cardiovascular response is regulated by multiple adrenoceptor subtypes with structural homology. To date, nine homologous adrenergic receptor subtypes have been described. Only one study has found a gene-gene interaction upon CV disease incorporating two adrenergic receptor subtypes. Genetic variants in all the nine adrenergic receptor subtypes have never before been investigated in a single study as this study will do.

DESIGN NARRATIVE:

The study will evaluate the effects of genetic variants in all of the nine adrenergic receptor subtype genes, alone or in combination, on CVR and other quantitative cardiovascular traits in a population of 1048 healthy youth. Subjects are black and white twins that have already been comprehensively phenotyped as part of the Georgia Cardiovascular Twin Study (HL56622). Racial differences in adrenoceptor gene effects will receive special attention, because such differences may offer a partial explanation for the higher prevalence of essential hypertension (EH) in blacks. Primary measures are systolic BP at rest and in response to two behavioral stressors. Secondary measures are diastolic BP, cardiac output and total peripheral resistance (TPR) at rest and in response to the stressors, left ventricular mass (LVM), endothelium dependent arterial dilation to reactive hyperemia (EDAD), arterial stiffness and 24-hour ambulatory BP. This data set will be expanded through collection of buccal cell DNA from the parents of the twins, enabling performance of TDTs (transmission disequilibrium tests) and haplotype reconstruction and analyses. This candidate gene study in a large group of black and white twins including TDT and haplotype analyses provides an innovative approach to help identify individuals at particular risk for the development of EH and improve options for primary prevention as well as individualized therapy of EH (pharmacogenetics).

Conditions

Cardiovascular Diseases; Heart Diseases; Hypertension

Eligibility Criteria

Inclusion Criteria

No eligibility criteria

• Minimum Eligible Age: 14 Years
• Maximum Eligible Age: 25 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

National Heart, Lung, and Blood Institute (NHLBI)

NIH

Sponsor Role: lead

Principal Investigators

Yanbin Dong

Role:

Augusta University

Other Identifiers

R21HL076723

Identifier Type: NIH

Identifier Source: secondary_id

View Link

1256

Identifier Type: -

Identifier Source: org_study_id