This may be altered in hypertensive disorders of pregnancy (HDP) with one study reporting an overall elevation of ANP in pregnancy-induced hypertension with a similar response to postural stimuli (Lowe et al., 1991b), while another reports no significant difference in baseline ANP and no significant differences with a head-down tilt (Poulsen et al., 1995). The gene discussed is NPPA; the disease is hypertensive disorder.