MN BLOOD-GROUP, A GENETIC-MARKER FOR ESSENTIAL ARTERIAL-HYPERTENSION IN YOUNG-ADULTS

The MN blood group has been linked with blood pressure levels and sodi um-lithium counter-transport in red blood cells of normotensives. The aim of the study was to compared the distribution of MN phenotypes acc ording to age at diagnosis of essential hypertension and to investigat e the relationship between MN phenotypes, severity of complications an d therapeutic needs. MN blood group polymorphism was studied in 386 Ca ucasians with established essential arterial hypertension, treated for at least one year. In 285 healthy normotensive blood donors, blood pr essure was measured and MN blood group was typed. MN blood group were typed with polyclonal antisera and confirmed with monoclonal antisera. MN blood group phenotype frequencies in hypertensives were 0.207 (MM) , 0.601 (MN), and 0.192 (NN), which differs (P<0.000002) from the dist ribution in the controls: 0.270 (MM), 0.540 (MN) and 0.189 (NN). The r elative MN phenotype frequency was strongly over-represented (P<0.05). Age at detection of hypertension was significantly lower for MN patie nts (P<0.0005). With increasing age of detection, the relative frequen cy of MN phenotype gradually decreases from 0.73 in those detected bef ore age 40 to 0.50 for patients detected after age 60. This observatio n holds true for both male and female hypertensives. Furthermore, hype rtensives with an MM blood group had a lower (P<0.05) prevalence of ce rebrovascular accidents. In controls, blood pressure was comparable fo r the three MN phenotypes. The present study suggests that the MN phen otype is a genetic factor associated with early detection of essential hypertension.