Preliminary evidence for genetic determination of intraerythrocytic sodium concentration in Utah pedigrees.

Intraerythrocytic sodium concentration has been reported to be increased in hypertensive individuals and some of their normotensive relatives. We investigated the "familiality" of this trait in 572 nonhypertensive subjects from 34 Utah kindreds. Most of these kindreds were selected because of a high incidence of hypertension, heart attack, or stroke. Intraerythrocytic sodium concentration was correlated with the sex of the subject and suprailiac skinfold thickness. Intraerythrocytic sodium concentration was adjusted by linear regression for these 2 factors. The residual values were positively correlated in parent-offspring pairs and among sibs, both those presumed to be living together and those presumed to be living apart. The spouse-spouse correlation was not significant. Pedigree analysis suggested a mixed major-gene/polygenic model of inheritance, but these data did not allow us to distinguish between dominant and recessive inheritance for the major gene component. Total heritability due to both major-gene and polygenic components was estimated to be 90-95%; the proportion of the total variance due to polygenes was estimated to be 60-75%. These results suggest that further study of the relationship between the inheritance of intraerythrocytic sodium and the pathophysiology of hypertension is warranted.