Genetic analysis of sodium-lithium countertransport in 10 hypertension-prone kindreds.

The rate of sodium-lithium countertransport (SLC flux) across red cell membranes has been reported to be elevated in hypertensive persons and their relatives as compared to normotensive individuals without family histories of hypertension. We have investigated the inheritance of this trait in 434 persons from 10 kindreds. Relatives show positive correlation of SLC flux values, but there is no spouse-spouse correlation. Pedigree analysis favors a model of polygenic inheritance over models of major-gene inheritance. Major-gene index statistics and offspring-between-parent statistics provide similar results. The proportion of total phenotypic variance that is attributable to polygenic differences between persons is estimated at 71%. The SLC flux values of hypertensive persons in this study population are lower than those reported from Boston, but are similar to those reported from Europe. We found a broad overlap of SLC flux values for hypertensive and normotensive persons. We conclude that SLC flux probably is not useful as a preclinical marker for essential hypertension.