ObjectivesTo review, on a genome-wide scale, a linkage result obtained in an earlier candidate gene analysis in this same study sample, and to look for other possible contributing genetic loci predisposing to hypertension in this population.DesignAn affected sibpair linkage study with highly polymorphic genetic markers spanning the genome at an average intermarker density of 10 cM.ParticipantsA total of 47 families with two affected siblings (mostly dizygotic twins) and all available additional family members from the genetic isolate of Finland. The families were identified through the Finnish Twin Cohort Study, the total number of this follow-up cohort being 13 888. The study sample was selected on the basis of early-onset hypertension with minimal presence of other phenotypic risk factors such as obesity.ResultsThe AT1locus stood out as the most significant locus in this population (maximum likelihood score 4.04). Some evidence for linkage was also detected with markers on chromosomes 2q (maximum likelihood score 2.96), 22q (2.07), and Xp (2.41).ConclusionsOur results establish the role of the AT1locus, on a genome-wide scale, as a major contributing locus to essential hypertension in this study sample.