[Human isodicentric X-chromosomes].

The large submetacentric abnormal late replicating X-chromosomes were found in three patients under karyological studies of 168 patients with Turner's syndrome. G- and C-banding revealed that abnormal chromosomes are three variants of isodicentric chromosomes resulting from the junction of the short arms of two X-chromosomes. The patients' karyotypes are respectively: 45,X/46,X,dic (X)(qter leads to p22: :p22 leads to qter); 46X,dic(X)(qter leads to p21: :p21 leads to qter); 46,X/46,X,dic(X)(qter leads to p11: :p11 leads to qter). All the three patients had different size deficiencies of the short arm of the X-chromosome. Partial X-monosomy caused the appearance of features of the Turner syndrome, which was less expressed in our patients compared to those with the entire X-monosomy.