1. ¹Division of Epidemiology and Community Health, University of Minnesota, Minneapolis, Minnesota
2. ²Department of Human Genetics, University of Utah, Salt Lake City, Utah
3. ³Cardiovascular Genetics Research Clinic, Department of Internal Medicine, University of Utah, Salt Lake City, Utah
4. ⁴Division of Biostatistics, Washington University School of Medicine, St. Louis, Missouri
5. ⁵Department of Epidemiology, University of North Carolina, Chapel Hill, North Carolina
6. ⁶Division of Preventive Medicine, University of Alabama-Birmingham, Birmingham, Alabama.

Correspondence: Dr. James S. Pankow, Division of Epidemiology and Community Health, University of Minnesota, 1300 South Second Street, Suite 300, Minneapolis, MN 55454 E-mail: pankow@epi.umn.edu

^*This hypertension network is funded by the following cooperative agreements (U01) with the National Heart, Lung, and Blood Institute: HL54471, HL54472, HL54473, HL54495, HL54496, HL54497, HL54509, and HL54515.

Received 9 November 2004; Accepted 3 December 2004.

Abstract

Background: Postural change in systolic blood pressure (SBP) is prospectively associated with several disease outcomes including hypertension, stroke, and coronary heart disease. The objective of this study was to characterize further a possible quantitative trait locus on chromosome 18q21 influencing SBP response to a postural challenge.

Methods: A prior genome scan of postural SBP response in 636 subjects of white ethnicity from 285 hypertensive sibships in the Hypertension Genetic Epidemiology Network (HyperGEN) indicated suggestive evidence for linkage on chromosome 18q21. This study included a de novo set of 452 African American pedigrees from the HyperGEN study and an expanded set of 372 white pedigrees. Variance components linkage analysis of postural SBP change was conducted using microsatellite markers on chromosome 18, and association studies were performed with a common single nucleotide polymorphism (variant 13) in the gene encoding NEDD4L, a key regulator of fine sodium reabsorption in the distal nephron.

Results: Combined analysis of all white and African American pedigrees yielded a LOD score of 4.25 at 80 cM on chromosome 18q21, with at least nominal evidence of linkage at this position in both white (LOD: 3.43) and African American (LOD: 1.14) subjects. Postural SBP response was associated with variant 13 of the NEDD4L in a subset of white subjects taking medications effective in treating sodium volume-dependent hypertension (₁-blockers, calcium channel blockers, and/or diuretics).

Conclusion: These data provide further evidence for a quantitative trait locus on chromosome 18q21 influencing postural change in SBP.