Erdheim-Chester Disease (ECD) is a rare form of histiocytosis characterized by the proliferation of blood cells, known as histiocytes, which infiltrate various organs and tissues, often causing irreversible damage. The causes of the condition are still unknown, and although some mutations in genes involved in cell proliferation have been identified, other factors may be involved. Susceptibility to developing rare diseases like ECD is typically associated with genetic factors, including DNA polymorphisms and epigenetic modifications. This study aims to analyze the entire genome of a large cohort of patients with ECD and healthy controls to determine whether there are polymorphisms and epigenetic variants associated with susceptibility to developing the disease. The study could thus clarify the genetic predisposition to ECD development, provide insights into disease pathogenic mechanisms, and identify proteins or cellular mechanisms potentially targeted by specific treatments.