The HyperGEN network has taken the lead in studying associated subphenotypes of hypertension and will study the following: measures of metabolic intermediates such as plasma insulin, glucose and lipid levels, and red cell sodium-lithium transport; co-morbidity with diseases of possible common etiology such as diabetes, obesity, and hypertension-associated kidney disease; degree of specific target organ damage; differential response to environmental input; and left ventricular hypertrophy and other phenotypes measured by echocardiography. Co-morbid conditions and measures of end-organ damage will be used as stratifying variables. Genes that influence variation in measures of metabolic intermediates, blood pressure response to stressors, and left ventricular hypertrophy will be studied in linkage and association studies. Environmental exposures (medication use, activity level, smoking) will be used as covariates. These measurements will allow for the identification of genes that influence variation in these subphenotypes, some of which may overlap with genes that influence blood pressure levels per se, and others which may be specific to the associated phenotype, nearly all of which have heritabilities equivalent to or greater than blood pressure by itself.