Meiotic behaviour and sperm aneuploidy in an infertile man with a mosaic 45,X/46,XY karyotype.
The meiotic behaviour of the germ cells in 45,X/46,XY men has not been extensively studied. This study investigated the meiotic events and sperm aneuploidy in an azoospermic man with a 45,X/46,XY (50/50) mosaic karyotype to better understand the fate of the 45,X cells and the production of chromosomally abnormal spermatozoa. Combining immunofluorescence techniques and fluorescence in-situ hybridization, meiotic recombination, synapsis, meiotic sex chromosome inactivation (MSCI) and configuration were analysed, as well as sperm aneuploidy in the patient and 10 normal, fertile men. Despite the 50:50 somatic mosaicism in the patient, 25% of pachytene cells analysed were 45,X. Furthermore, 63% of pachytene cells were 46,XY with paired sex chromosomes, and 12% were 46,XY with unpaired sex chromosomes, which displayed abnormal MCSI patterns. Although the patient's testicular spermatozoa showed increased aneuploidy, the majority were of normal constitution. The X:Y sperm ratio was significantly increased compared with the controls (P < 0.001), which may indicate that some 45,X cells gave rise to X-bearing spermatozoa. The findings provide insight into the fate of 45,X/46,XY cells in meiosis, supporting the hypothesis that stringent checkpoints ensure the favourable production of spermatozoa with normal chromosomal constitution despite an individual's abnormal karyotype.
Department of Obstetrics and Gynecology, University of British Columbia, Vancouver, BC, Canada V6H 3N1.
He
H
Ren
Department of Obstetrics and Gynecology, University of British Columbia, Vancouver, BC, Canada V6H 3N1.
Victor
V
Chow
Department of Obstetrics and Gynecology, University of British Columbia, Vancouver, BC, Canada V6H 3N1. Electronic address: sai@mail.ubc.ca.
Sai
S
Ma
D000328:Adult; D000782:Aneuploidy; D041321:Chromosomes, Human, X; D041322:Chromosomes, Human, Y; D005260:Female; D006801:Humans; D007248:Infertility, Male / Q000235:genetics* / Q000473:pathology; D059785:Karyotype; D007621:Karyotyping; D008297:Male; D008540:Meiosis / Q000235:genetics*; D009030:Mosaicism; D012729:Sex Chromosome Aberrations; D013094:Spermatozoa / Q000378:metabolism* / Q000473:pathology
male infertility; meiosis; meiotic sex chromosome inactivation; sex chromosome mosaicism; univalent X chromosome; unpaired sex chromosomes