SUMMARY
Rare diseases and disorders constitute important clinical problems. There are many concerns among physicians while planning the diagnostic and treatment process of such a heterogenous group of patients. These concerns arise not only from the rarity of cases, but also from multiple gaps in knowledge on the management of patients with rare diseases and disorders. The commonly accepted prevalence of rare diseases and disorders is 1 per 2 000 in the general population or less. Incidental prevalence and multiplicity of comorbidities result in an inability to gather enough experience at any single centre. Thus, cooperation and the exchange of ideas is important for the management of patients with rare diseases. Classification of rare cardiovascular diseases and disorders (RCDD) is crucial for expanding knowledge in the field of RCDD. It consists of an overview of RCDD, facilitates clinical approaches to patients and makes the creation of registries and databases easier. We hope that the updated RCDD classification will aid medical practice through the contribution to progress in diagnostics and therapy. It also serves as a summary of scientific achievements in the field of RCDD. Without the grouping of specific disorders, it is very difficult to create diagnostic and therapeutic algorithms. The Classification of RCDD was published for the first time in the Journal of Rare Cardiovascular Diseases (JRCD) in 2013 [1]. RCDD classification was discussed during the 2013 European Society of Cardiology Congress held in Amsterdam (www.crcd.eu/?p=2800) and in international journals, including a recent publication of the European Heart Journal [2, 3]. Clinical classification of RCDD takes into account major clinical symptoms and pathologies and is based on common clinical and/or anatomical features.