Frequency of tri- and multiradial configurations in fragile X chromosomes

The appearance of tri- or multiradial configurations in fragile chromosomes is affected by the number of cell cycles in the folate antagonist system. In this study the lymphocytes were incubated for 96 h in a medium 199 without calf serum, and tri- or multiradial configurations were observed in 6 of 12 cases of fra(X) chromosome. The frequency ranged from 0.6% to 7.4% of fra(X) chromosomes.