GENDER PRESELECTION IN HUMANS - FLOW CYTOMETRIC SEPARATION OF X-SPERMATOZOA AND Y-SPERMATOZOA FOR THE PREVENTION OF X-LINKED DISEASES

Human X- and Y-chromosome-bearing spermatozoa were separated based on their DNA content, using modified flow cytometric cell sorting technol ogy. The resulting separation purity of the X-bearing from Y-bearing s permatozoa was evaluated using in-situ hybridization with alpha satell ite DNA probes for the X- and Y-chromosomes. In the putative X-enriche d-sorted populations, an average of 82% of the spermatozoa showed a hy bridization signal with the X probe. Similarly, in the Y-sorted popula tion 75% gave a signal with the Y probe. Sorted X- and Y-bearing sperm atozoa were found to maintain their viability for several hours after sorting. These results demonstrate that the human sperm sex ratio can be significantly shifted to favour the selection of female-producing ( X) spermatozoa or male-producing (Y) spermatozoa when spermatozoa are flow cytometrically sorted on the basis of DNA content. We propose tha t flow cytometrically sorted human spermatozoa, used in conjunction wi th in-vitro fertilization or intra-oviductal insemination, could be us ed by families who are at risk for X-linked diseases to preferentially produce female offspring. Sorted spermatozoa could also be used to pr e-select for male offspring if that were medically indicated.