[Molecular cytogenetic study of short arm aberrations in human D and G group chromosomes].

Many structural and functional characteristics in the cen-pter regions of human D and G group chromosomes play important roles in the etiology of genetic diseases and cancer. Six cases of Dp+/Gp+, 10 cases of D/G translocation, 1 case of extra small chromosome (mar), and 1 case of Yqs were studied with molecular and cytogenetic techniques. The results showed the Ag-NOR frequency of the Dp+/Gp+ group to be significantly higher, but their satellite association frequency lower than those of normal controls. Autoradiographic silver grains were not found along the entire p+ part of the marker chromosome by using chromosomal in situ hybridization techniques. This result is somewhat different from what we had reported previously. It is suggested that the mechanism of p+ formation may vary among different cases. Diversified nucleolar organizer transcription sites may exist in the rRNA gene cluster region of chromosomes. The results of Ag-NOR and in situ hybridization of D/G translocation cases indicate that they have lost their NOR. Study of the extra small chromosome case and the Yqs case suggested that mar and Yqs exert no effect on the phenotype.