Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 39 1 2010 03 15 96 99 AM El-Tawil 2015 10 03 Inflammatory bowel disease, coronary artery disease, cerebrovascular disease, hypertension, diabetes, tumours, are exam­ples of chronic degenerative diseases that have a high prevalence in developed nations. These chronic-non-communicable dis­eases have multifactorial aetiologies that considered to be caused by the interaction of environmental risk factors with multi­ple predisposing genes. Genetic researches on these diseases have traditionally focused on investigation aimed at identify­ing disease-susceptibility genes. Recent evidence suggests that somatically acquired DNA mutations may also contrib­ute significantly to the pathogenesis of these disease states such as coronary artery disease indicating a similarity be­tween the atherosclerotic and carcinogenic processes. The high incidences and prevalence of these chronic diseases in the West­ern World in comparison with the East and changing trends in disease incidence (seen in many countries) provide strong evidence that those environmental factors as playing a major influence in disease- expression. There is an ample reason to be­lieve that environmental factors have contributed to inducing alterations in genetic code in precedent generations, which were subsequently inherited and further modified by modern life style   activities. Consequently, we now see the appearance of chronic degenerative diseases and their higher incidences in the Western nations   as compared with the Eastern ones. https://ijph.tums.ac.ir/index.php/ijph/article/view/3140 https://ijph.tums.ac.ir/index.php/ijph/article/download/3140/2939