In recent years, Genetics has been experiencing a genuine revolution, which has had a substantial impact on Medicine. Currently, Genetics is being applied at the diagnostic and prognostic level to a large number of diseases. New advances in this area and the precise diagnosis and characterization of many genetic diseases will lead to the development of new therapeutic strategies and strengthen the foundations of a Personalized Medicine. In Medicine, more and more, Genetics is not only a tool for the study of genetic diseases but is also an integral part of the study of disease, as a cause or as a factor. The knowledge of the pathophysiology of non-genetic diseases cannot be understood today without the contribution of Genetics. Many disciplines of medicine are enriched by advances in genetics such as pharmacology (pharmacogenomics). The increased precision and early diagnosis of genetically based diseases gives significant advantages from the point of view of prognosis, prevention, and even therapy for a growing number of pathologies. This contributes to a reduction in morbidity and mortality from this type of disease, an increase in the quality of life of this type of patient and a greater rationalization of diagnostic tests or of certain therapeutic measures. We must bear in mind that, at present, we know of more than 6,000 human diseases with a marked genetic component, of which a high percentage are hereditary. Almost all of these diseases are classified as rare due to their low frequency. However, if we take all of them together, their social impact is very large, affecting between 3-8% of the population. Rapid advances in research in this field result in a significant gap between scientific possibilities and their direct application in daily clinical practice. In addition, this research leads to new fields of application that require great specialization. In this context, it is necessary for Health professionals to have a basic knowledge of Genetics and especially Human Genetics, in order to understand the pathophysiological bases of a large number of genetic diseases, their characteristics and clinical, family and social implications; to learn to identify them and be up-to-date on the diagnostic, prognostic and therapeutic possibilities of a growing number of genetic diseases. To date, diagnostic efforts have focused on monogenic diseases and diagnostic protocols are available for nearly 2,000 diseases. Furthermore, as these are usually developments based on recent research, the scarcity and heterogeneity of the available sources of information create large gaps of diagnostic uncertainty. However, it should be noted that the group of the most frequent diseases, and those that have the greatest impact on the population, is specifically the multigenic and multifactorial diseases. Among these we find some as frequent as cardiovascular, neuromuscular, neurodegenerative diseases (Alzheimer's, Parkinson's, etc.), mental retardation, asthma or cancer. It is essential that there is easy communication between the laboratory that studies diseases, variants, etc. and the clinical medicine that studies particular cases. In this subject we will try to facilitate this approach so that patients benefit from translational medicine.