Polygenic and miltufactorial disorders

Many factors influence our susceptibility to disease. These include our stress load, our environment and the toxins we absorb from it, the total number of infectious agents we are exposed to as well as our underlying genetic susceptibility to these diseases. Multifactorial is the term given to the mode of transmission shown by a large number of diseases which show familial clustering but which is not in accord with any recognized pattern of single gene inheritance. These diseases include several common congenital malformations and acquired disorders of childhood and adult life. The underlying genetic mechanism is thought to involve interaction of relatively large numbers of genes - hence oligogenic or polygenic - with environmental factors. The ultimate cause of Alzheimer’s (AD) is unknown. Genetic factors are suspected, and dominant mutations in three different genes have been identified that account for a much smaller number of cases of familial, early -onset AD. For the more form of late onset AD, ApoE is the only repeatedly confirmed susceptibility gene. Coronary artery disease is well-recognized complication of several single-gene disorders involving lipid metabolism. Over 20 genes have been proposed as candidates for polygenic coronary artery disease. These include genes which control lipid metabolism, blood pressure, clotting, and fibrinolysis.