NOR activity in two families with balanced D;D translocations and numerous consecutive miscarriages

Ag-staining of the nucelolus organizers (NOR) was studied in the acrocentric chromosomes identified by Q-banding in lymphocyte cultures from nine members of two families wit balanced D;D translocations. The D;D translocations were dicentric, t(13;14) and t(13;15). The translocation chromosomes did not show NOR-activity. The modal numbers of Ag-positive NORs were normal (5–9) in both the translocation carriers and the individuals with normal karyotypes. The NORs were inherited unaltered from parent to child in both families as shown by fluorescent markers and the size of the silver precipitate on the individual acrocentric chromosomes.