A 13-year-old girl selected for chromosome investigations because of mental deficiency and multiple malformations was found to be a 48, XXXX/ 49, XXXXX mosaic. Multiple sex chromatin bodies, up to four, were found in oral mucosa smears and in cultured fibroblasts. Two cells with drumsticks were found in scoring 1,000 granulocytes. Autoradiography revealed cells with three and with four late-replicating X chromosomes. Analysis of the patterns of replication along the individual late-replicating X chromosomes in each cell revealed a certain degree of asynchrony among them. In both types of cells, with four and five X’s, the long arms of the X were the last to terminate synthesis. In the occasional cell there was marked internal asynchrony in this respec
展开▼
