The technical variables associated with the frequencies of QFQ, RFA and CBG heteromorphisms of human chromosomes.

In the 1971 Paris Conference (1972) it was established that certain regions of human chromosomes show remarkable heteromorphisms. These are the short arm of acrocentric chromosomes, the secondary constriction regions of chromosomes 1, 9, 16, and the distal 2/3rd of the long arm of the Y and the centromere of chromosomes 3, 4, and 5. There are several technical variables which affect the frequency of these heteromorphisms. These include quality of culture, age of slide, photography (filter, etc.), method of printing and method of scoring (criteria). Several other variables in the production of QFQ, RFA, and CBG heteromorphisms are discussed. In order to compare results from different laboratories these variables must be taken into consideration.