A Human Family Suggesting Evidence for Centric Fission and Stability of a Telocentric Chromosome

Abstract

One of the female members of a family with hereditary D/D-translocation chromosome was found to be mosaic for two major cell lines. One of her cell lines was consistent with balanced D/D-translocation, i.e., 45, XX, D–D–, t (DqDq). Her other cell line had each cell with 46chromosomes. In these cells, however, a normal D-chromosome was replaced by a telocentric ‘marker’ chromosome with comparable size of the long arm of a D-chromosome. The mosaic carrier has transmitted this ‘marker’ chromosome to her son. It is interpreted that during the embryonic life of the female carrier, one of the cells with the translocation D/D-chromosome underwent centric misdivision that was followed by a pericentric inversion in one of the telocentrics. These two processes apparently gave to a stable telocentric D-chromosome and a regular D-group chromosome.