Meiotic behaviour of the sex chromosomes in three patients with sex chromosome anomalies (47,XXY, mosaic 46,XY/47,XXY and 47,XYY) assessed by fluorescence in-situ hybridization

Meiotic studies using multicolour fluorescent in-situ hybridization (FISH) and chromosome painting were carried out in three patients with sex chromos ome anomalies (47,XXY; 46,XY/47,XXY and 47,XYY),In the two patients with Kl inefelter syndrome, although variable percentages of XXY cells (88.5 and 28 .3%) could be found in the premeiotic stages, none of the abnormal cells en tered meiosis, and all pachytenes were XY, However, the abnormal testicular environment of these patients probably resulted in meiotic I non-disjuncti on, and a certain proportion of post-reductional cells were XY (18.3 and 1. 7%), The fact that none of the spermatozoa were XY also suggests the existe nce of an arrest at the secondary spermatocyte or the spermatid level, In t he XYY patient, most (95.9%) premeiotic cells were XYY, The percentage of X YY pachytenes was 57.9%, The sex chromosomes were either in close proximity (XYY) or the X chromosome was separated from the two Ys (X + YY), A high p roportion (42.1%) of post-reductional germ cells were XY, However, only 0.1 1% of spermatozoa were disomic for the sex chromosomes, In this case, the d ata suggest the existence of an arrest of the abnormal cells at the primary and the secondary spermatocyte or the spermatid level, giving rise to the continuous elimination of abnormal cells in the germ-cell line along sperma togenesis, The fact that the proportion of diploid spermatozoa was only inc reased in one of the three cases (XXY) is also suggestive of an arrest of t he abnormal cell lines in these patients, The two apparently non-mosaic pat ients were, in fact, germ-cell mosaics. This suggests that the cytogenetic criteria used to define nonmosaic patients may be inadequate; thus, the ris k of intracytoplasmic sperm injection in apparently non-mosaics may be lowe r than expected.