en Biological Sciences Biological Sciences Original Research Original Research The term mitral valve prolapse (MVP) is used for a particular subset of patients with hyperadrenergic dysautonomia. It occurs when part of a leaflet or both leaflets of the mitral valve extend above the plane of the atrioventricular junction during ventricular systole. The adenylate cyclase activity in MVP dys-autonomia was studied by extraction of enzyme from the erythrocytes from 62 normal subjects and 78 MVP patients. Adenylate cyclase activity in the MVP group was increased compared to that in controls [6.51 ±O.38 (mean±S.D., n= 78) vs. 2.76 ±O.12, n= 62, U activity/mg erythrocyte protein, p<O.05]. The determination of adenylate cyclase activity in combination with echocardiography allows a reliable diagnosis of MVP patients. Mitral valve prolapse, MVP dysautonomia, adenylate cyclase. 167 170 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-298-383&slc_lang=en&sid=1 D QUJEQ 20031947532846004571 20031947532846004571 Yes From the Biochemistry and Biophysics Department, Babol University of Medical Sciences, Babol, I.R. Iran