The balkan endemic nephropathy (BEN) has been known for five decades. Its etyology, however, has remained unknown so far. Starting from the assumption that the existence of BEN can be based upon the genetic dispositions of certain individuals, the population and genetic structure of BEN patients is compared in practice to the population and genetic structure of healthy (control) individuals. Accordingly, the frequency of 20 anatomical and physiological characteristics, selected by chance, which are controlled by several or very little genes with alternative, dominantly recessive mode of expression is analysed. The assumption of the possibility of discovering differences among BEN patients and healthy people at the level of tested anatomical and physiological characteristics can be explained in at least three ways: a) the appearance of BEN and immunity to factors which cause the disease depend of genes which simultaneously exert a pleotropical influence over the whole number of other characteristics, and hence manifest themselves correlatively; b) genetic disturbances originating from the increased recessive homozygoticity to a number of characteristics are the reason for decreased immunity to external factors which may cause this disease. c) BEN patients may be descendants of immigrants with different population and genetic structure which can also be manifested through different frequences of characteristics such as, qualitative anatomical and physiological characteristics.
    Five out of 20 analysed patients recessive phenotypes express a significantly greater frequency among BEN patients than among healthy (control subjects). Considering that the analysed qualitative characteristics have been selected by chance and that they are under relatively simple genetic control, it can be assumed that the genetic structures of the patients differ from those of the healthy people in approximately 25% of gene allels. Medical findings suggest the possibility of the association of the corresponding gene allels with the genetic base for BEN. Genetic disturbances influenced by the increase of recessive homozygotism of BEN patients could represent the cause of decreased immunity to external factors responsible for the onset of the dissease. Acta Medica Medianae 2004; 43(1):11–18.

    Key words: balkan endemic nephropathy, population genetics