Non-random chromosome positioning in human sperm and sex chromosome anomalies following intracytoplasmic sperm injection

Abstract

Chromosome paint for chromosome 18 hy b ridised in more than 80% (190/234) of sperm examined, and chromosome paint for X chromosome hy b ridised in just over 40% ( 2 3 0 / 5 5 3 ) . The sperm tail was used as a reference to identify apical or basal position. Chromosome 18 was found near the s p e rm tail in almost 60% of the sperm (113/190), while the X chromosome was found near the sperm tail in less than 40% ( 8 8 / 2 3 0 ) . This shows that chromosome 18 is preferentially l o c ated in the basal region of the sperm nucleus, while the X chromosome is preferentially located in the apical regi o n . The placement of chromosomes within the sperm nucleus m ay have implications for assisted reproductive technologi e s ( A RT ) , and may help explain the apparent increase in sexchromosome aberr ations in ICSI offspri n g . This increase could be due to the fact that the X chromosome in sperm nuclei preferentially localises in the apical regi o n .I n such n u c l e i , the S-phase of the cell cycle may be delayed due to the decreased rate of nuclear decondensation in the apical regi o n of the sperm head, h i n d e ring progression to the onset of firs t mitosis in the zygote. This may lead to mitotic err o rs in the d i s t ri bution of the X chromosome during first cleava g e , implying that such positioning of the sex chromosome could lead to the increase in sex-chromosome anomalies follow i n g I C S I . All animal procedures were approved by the ORPRC Institutional A n i m a l Care and Use Committee. Human sperm were obtained from the Fo l l a s L a b o r at o ries after Institutional Review Board approva l .This research wa s sponsored by grants to GS by the NIH.