The radial positions of the centromeric regions of chromosomes 1 and X were 
determined in normal male fibroblasts (XY) and in fibroblasts from a patient 
with a rare case of XXXXY polysomy. The centromeric regions and presumably the 
whole territories of active X chromosomes were demonstrated to occupy similar, 
although not identical, positions in XY and XXXXY cells. The centromeres of 
inactive X chromosomes (Barr bodies) were located closer to the nuclear 
periphery as compared with the centromeres of active X chromosomes. In addition, 
it was established that the nuclear radial position of gene-rich chromosome 1 
was changed in XXXXY cells as compared to normal XY cells. The data are 
discussed in the context of the hypothesis postulating that changes in nuclear 
positioning of chromosomal territories induced by the presence of extra copies 
of individual chromosomes may contribute to the development of diseases related 
to different polysomies.