The aim of this paper is to present a database of isolated communities (CENISO) with high prevalence of genetic disorders or congenital anomalies in Brazil. We used two strategies to identify such communities: (1) a systematic literature review and (2) a "rumor strategy" based on anecdotal accounts. All rumors and reports were validated in a stepwise process. The bibliographical search identified 34 rumors and 245 rumors through the rumor strategy, and 144 were confirmed. A database like this one presented here represents an important tool for the planning of health priorities for rare diseases in low- and middle-income countries with large populations.