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Figure 3 BP Response to Environmental (Cold) Stress in Twin Pairs: Effect of CHGA Common Allelic Variant C+87T in the 3'-UTR, as Well as Sex

Provocation of efferent sympathetic outflow was undertaken in each subject by immersion of 1 hand in ice water (at 0°C) for 1 min, with continuous blood pressure (BP) monitoring. Results are shown for final (post-cold) systolic blood pressure (SBP), and analyzed by generalized estimating equations, establishing an exchangeable correlation matrix to take into account intratwin-pair correlations. (A) CHGA C+87T genotype effect on post-stress SBP; data are shown in all persons, as well as men and women separately. Genotype affected the trait (p = 0.042), and there was no gene-by-sex interaction (p = 0.159) on trait. (B) Sex effect on post-stress SBP (p = 0.009). 3'-UTR = 3'-untranslated region.