From rumors to genetic isolates

Here we propose a registration process for population genetic isolates, usually geographic clusters of genetic disorders, based on the systematic search of rumors, defined as any type of account regardless of its reliability. Systematically ascertained rumors are recorded, and validated through a progressive process of pre-established steps. This paper outlines the conceptual basis for this approach and presents the preliminary results from a rumor-based nationwide registry of genetically isolated populations, named CENISO (Censo Nacional de Isolados), operating in Brazil since 2009. During the first four years of its existence (2009–2013), a total of 191 Rumors were registered and validated, resulting in a prevalence rate of one per million inhabitants of Brazil. When the five statutory geographic regions of Brazil were considered, more Rumors were registered for the Northeast (2.11; 1.74–2.54 per 10(6)) than for the remaining four regions, North, Center-West, Southeast, and South, which did not differ among themselves. About half (86/191) of the recorded rumors were proven to be geographic clusters; of these disorders, 58 were autosomal recessive, 17 autosomal dominant, 5 X-linked, 3 multifactorial, and one environmental (thalidomide embryopathy).