Delineation of human prometaphase paracentromeric regions using sequential GTG- and C-banding.

The centromeric-paracentromeric regions of high-resolution human chromosomes have not been examined in detail. It is not clear which bands in the paracentromeric regions are included within the heterochromatin and are therefore not clinically meaningful, and which bands are excluded. This makes breakpoint analysis in these regions difficult. Using sequential G- and C-banding of high-resolution chromosome preparations from four clinically normal subjects and from one patient with a very small interstitial deletion of the chromosome 16 long arm, we have made a detailed analysis of the centromeric-paracentromeric regions of each chromosome and of the entire Y chromosome at the 400, 550, and 800-850 band stages. We present here the results of analysis of preparations at the 800-850 band stage.