Rare diseases affect between 8-10% of the population. There are registries that describe these diseases but there is limited literature that reviews their characteristics, scope and limitations.

A narrative review was designed that would cover literature from the last 10 years that described the limitations and geographic localizations of rare diseases registries, following SANRA guidelines. The search was carried out on Medline, Lilacs, Cochrane, Clinical Trials and Orphanet.

978 articles were eligible from which 26 were selected for final review. 22 national registries were found, 10 from Europe. The scope was epidemiological, development of RCTs and improving interoperability between registries in most reviews. Regarding the country of origin, most were from USA, Italy, France, Spain and Germany. In Latin America, rare diseases registries are scarce, mostly from Uruguay and Argentina and depending on private funding.

Rare diseases registries correspond to a data collection system to describe a condition, typically of diseases related to each other. Their scope is mostly epidemiological and for recruitment of patients for RCTs. It is key to define primary and secondary objectives of rare diseases registries and perform quality control. The limitations are those of observational studies, such as selection bias, recollection bias and lack of standardized controls.