[Polymorphism of NOR bands in a normal French population]

The segregation of NORs-Ag positive and negative acrocentric chromosomes was studied with a combined staining technique (Ag-I/RHG), in a normal French population (Saint-Etienne, Loire, France). The observed frequencies of homozygous and heterozygous NOR-Ag individuals, either for each acrocentric pair or for all the pairs of acrocentric chromosomes are not statistically different from the ones expected according to Hardy-Weinberg's law. The genotypic frequencies of homozygous subjects (+/+) for each acrocentric pair are the following: 13: 0,900; 14: 0,895; 15: 0,880; 21: 0,900 and 22: 0,870. The average modal number of NOR-Ag positives for the sample is 8,58 +/- 0,81. The comparison between these results and other data from European Caucasian populations, was possible by using the same criteria of classification. The discriminative value of NOR banding polymorphisms is discussed.