Unraveling the Genetic Component of Multifactorial Diseases: Dream or Reality

The etiology of many human diseases is complex and very likely involves a combination of genetic and environmental risk factors. A popular strategy to detect genetic risk factors is to perform a systematic screening of the genome searching for linkage. The power of such and approach depends very much on the unknown characteristics of the genetic factors and the main difficulty is to establish a good trade-off between false positives and false negatives. Besides, a precise localisation of the risk factor will generally not be obtained. The set up of a candidate gene stratery is necessary to go further in genetic factor identification. It is likely that for multicfactorioal diseases the only genetic risk factors that can be detected are those with fairly strong effect. Even in that case, it is important to design strategies which increase the power of detection and provide for a better evaluation of the associated risks.