["Isolates" in an area of Balkan endemic nephropathy in Bulgaria].

Up to the time of World War II in some Bulgarian villages and in those with Balkan endemic nephropathy (BEN) including, conditions existed for isolates. Marriages from those settlements were with partners from the same or neighbouring endemic villages. As an illustration the highly endemic village B. Izvor (Vraza district) is cited where 505 marriages were registered for the time 1900-1945. In 93.6% of those marriages the second partner came from endemic regions as well. The conditions of isolates favoured the drift of gene for BEN. Two genetically isolated ethnic groups were differentiated in the endemic foci: Bulgarians and Gypsies, living under the same conditions of the endemic environment, but only Bulgarians were affected. Conclusions are drawn in favour of the genetic hypothesis in the etiology of BEN.