Genes affect virtually all human characteristics and diseases. These influences can be ascertained in individual patients through a review of the family history physical examination and the use of medical diagnostics. Aneurysms and dissections are a leading cause of morbidity and mortality, in addition to medical expense, and, on the whole, their specific molecular mechanisms are beginning to be identified. Over the past decade, genetic tests have become available for numerous heritable disorders especially inherited with mendelian models. An important fact is that the results of genetic tests may also be useful beyond the individual affected by the genetic disorder. Depending upon the disorder, knowledge of carrier status may be important. Because of these facts, some essential information regarding basic genetics of aneurysm and dissection has been presented in this study. (C) 2009 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.