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Cation transport markers as predictors of hypertension
1Department of Internal Medicine, University of Michigan, Ann Arbor 48109-0356.
Insights
Increased red blood cell lithium-sodium (RBC Li(+)-Na+) countertransport activity may indicate a genetic predisposition to hypertension. This finding suggests a potential premorbid marker for identifying individuals at higher risk for developing high blood pressure.
Area of Science:
- Genetics
- Cardiovascular Physiology
- Biochemistry
Background:
- Essential hypertension is linked to abnormalities in cation transport.
- Increased red blood cell lithium-sodium (RBC Li(+)-Na+) countertransport is a key candidate for a genetic marker of hypertension risk.
Purpose of the Study:
- To investigate the role of RBC Li(+)-Na+ countertransport as a genetically mediated marker for future hypertension.
- To explore the potential for a single genetic determinant influencing RBC Li(+)-Na+ countertransport activity.
Main Methods:
- Statistical modeling of countertransport values in populations.
- Pedigree studies to analyze genetic transmission of RBC Li(+)-Na+ intertransport activity.
- Prospective analysis of premorbid markers for hypertension.
Main Results:
- Population studies show countertransport values fit a mixture of two subpopulations, suggesting a major genetic influence.
- Genetic transmission studies indicate a Mendelian recessive pattern for RBC Li(+)-Na+ intertransport activity.
- Preliminary prospective analysis supports RBC Li(+)-Na+ countertransport as a predictive marker for future hypertension.
Conclusions:
- Increased RBC Li(+)-Na+ countertransport activity is a promising premorbid marker for genetic hypertension risk.
- A major monogenic influence, potentially on chromosome 4, may underlie high RBC Li(+)-Na+ countertransport.
- Allelic differences in the genetic locus controlling RBC Li(+)-Na+ countertransport may contribute to blood pressure variation.
Abstract:
Of the abnormalities of cation transport described in human essential hypertension, an increased maximal activity for red blood cell lithium-sodium (RBC Li(+)-Na+) countertransport is the most appealing candidate for a genetically mediated marker for risk of future hypertension. Population studies have demonstrated that the distribution of values for countertransport can be modelled statistically as a mixture of two overlapping subpopulations. These two modes could result from the action of a single principal determinant, and pedigree-based studies of the genetic transmission of RBC Li(+)-Na+ intertransport activity have suggested that factor may represent the effect of a major monogenic influence segregating in a Mendelian recessive fashion. Although the molecular nature of the proposed genetic lesion underlying high RBC Li(+)-Na+ countertransport is not yet known, a recent linkage study suggests it may be localized to chromosome 4. A preliminary report of a prospective analysis of the predictive value of high RBC Li(+)-Na+ countertransport for future hypertension supports its utility as a premorbid marker for genetic risk of future hypertension. Allelic differences at a genetic locus controlling RBC Li(+)-Na+ countertransport activity may contribute directly to interdividual blood pressure differences or may be linked to other genes that do.