Unit 6 (items 6.1 and 6.2) shows the Proteomic applications focused on understanding the molecular mechanism of different diseases based on the differential expression of proteins. Diseasome term is introduced to describe the relationship between different diseases and genes. Examples of clinical applications of proteomics study focused on cardiovascular disease, kidney disease and cancer are described. The ability of proteomics for marker discovery focused on the diagnosis and the development of new drugs is remarked. Finally, we describe how dietary compounds are capable of modulating gene expression (Nutrigenomics) and therefore cause a differential expression of certain proteins leading to chronic pathologies, and how proteomics can become a diagnostic tool. Thus, we introduce the concept of nutrition and/or personalized therapy in order to prevent, mitigate or cure chronic diseases.