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Genetic determination of NOR activity in human lymphocytes from twins
Human Genetics
|January 1, 1982
Abstract:
Activity of nucleolar organizer regions (NORs) was studied in cultured blood lymphocytes from 20 monozygotic (MZ) and 20 dizygotic (DZ) twin pairs. The number of Ag-stained NORs, the degree of staining, and the frequency of acrocentric associations were used as criteria of the NOR activity, the acrocentric chromosomes being identified by G-banding. Analysis of intrapair concordance as well as of intrapair variance showed the number of Ag + NORs and the size of Ag-deposits to be highly heritable traits. Intrapair differences in acorocentric association frequency were not significantly higher in DZ compared with MZ twins.