<qa>  How many people were originally examined 25 years ago?The study is a follow-up to one conducted in the 1970s and 1980s. The availability of 5 large kindreds first identified and recruited as part of the High Blood Pressure in the Young program is an important resource. The investigators have an extensive array of baseline data that was collected in the late 1970s and early 1980s on 750 participants stemming from that project, although some data are available only on a subset of participants. The present study population centers on 764 individuals in five large, multigenerational, extended families four white and one African-American originally examined 25 years ago. Data collected from the original participants include hundreds of biochemical, medical, physiological, behavioral, physical, psychological, genetic and demographic traits. 