Size variation polymorphisms of the short arm of human acrocentric chrosomes determined by R-banding by fluorescence using acridine orange (RFA).

One hundred normal Caucasians were studied by the RFA technique to estimate the frequencies of size variation of the short arm of acrocentric chromosomes. Each size variation was classified into one of five levels. The most frequent size level(code) was 3; therefore, this was regarded as the 'average' size. If one excludes the average size, the frequencies of size variation by RFA for chromosome 13, 14, 15, 21, and 22 were 22.5, 19.5, 14.5, 19, and 17% respectively. There was no significant difference for the overall frequencies of size variation between sexes. Furthermore, the RFA technique detects more variation in the size of human acrocentric chromosomes than any other method.