Genetic factors are involved in the etiology of most common diseases and traits present in populations. Different methodological approaches can be utilized to determine genes involved according to their genetic features in diseases. In the majority of conditions that follow a simple Mendelian pattern culprit genetic mutations have been identified. Conversely complex traits that are most common in the population are also the most difficult to identify. Finding these genes is crutial no just to clarify the pathophysiology of these common diseases but also to identify environmental factors involved and to improve their treatment, including in some specific cases gene therapy.

linkage disequilibrium; complex diseases; mendelian inheritance; genetic heterogeneity; genetic penetrance; genomic screening