(IMAGE) Tokyo Medical and Dental University Caption The collective activity of massive genes, known as polygenic activity, is involved in the development of hypertension. Some genes are expressed in the kidneys and adrenal glands to regulate blood pressure, but most are related to the development and function of the vascular system. The expression and function of these genes vary from person to person because of differences in the nucleotide sequence (single nucleotide polymorphisms (SNPs) marked with asterisks) that may be associated with disease. The sum of these differences is assessed by the polygenic risk score (PRS). This represents an individual's genetic risk of developing hypertension over their lifetime. Although maternal hypertension PRS is inversely corelated with offspring birth weight, the actual blood pressure of pregnant women had no such relationship with birth weight. Hypertension develops at an older age in women. This study revealed that it is not blood pressure, but the placenta, a vascular organ, that mediates the relationship between maternal hypertension PRS and birth weight. A higher maternal genetic risk of hypertension results in reduced growth of the placenta, which in turn hinders fetal growth. Credit Department of Molecular Epidemiology, TMDU Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.