Abstract
The mosaic 45,X/46,XY karyotype is a common sex chromosomal abnormality in infertile men. Males with this mosaic karyotype can benefit from assisted reproductive therapies, but the transmitted abnormalities contain 45,X aneuploidy as well as Y chromosome microdeletions. The aim of this study was to investigate the clinical and genetic characteristics of infertile men diagnosed with 45,X/46,XY mosaicism in China. Of the 734 infertile men found to carry chromosomal abnormalities, 14 patients were carriers of 45,X/46,XY mosaicism or its variants, giving a prevalence of 0.27% (14/5269) and accounting for 1.91% (14/734) of patients with a chromosomal abnormality. There were ten cases (71.43%, 10/14) of 45,X mosaicism exhibiting AZF microdeletions. Case 1 and Case 4 had AZFc deletions, and the other eight cases had AZFb+c deletions. A high frequency of Y chromosome microdeletions were detected in male patients with 45,X/46,XY mosaicism. Preimplantation genetic diagnosis should be offered to men having intracytoplasmic sperm injection for hypospermatogenesis caused by 45,X/46,XY mosaicism, to avoid the risk of transfering AZF microdeletions in addition to X monosomy in male offspring.
Highlights
The three main genetic factors known to cause male infertility are cystic fibrosis gene mutations that cause obstructive azoospermia, and chromosomal abnormalities and Y chromosome microdeletions that cause spermatogenic impairment (1)
The prevalence of 45,X/46,XY mosaicism or its variants in this male infertility study was 0.27% (14/ 5269), which is much higher than its incidence in newborns
An important finding of this study was the identification of the very high frequency (71.43%) of Y chromosome microdeletions in patients with sex chromosome mosaicism (45,X/46,XY)
Summary
The three main genetic factors known to cause male infertility are cystic fibrosis gene mutations that cause obstructive azoospermia, and chromosomal abnormalities and Y chromosome microdeletions that cause spermatogenic impairment (1). Infertile patients with severe spermatogenic impairment have an increased proportion of genetic abnormalities. The mosaic 45,X/46,XY karyotype is a common sex chromosomal abnormality associated with male infertility. The clinical phenotype of 45,X/46,XY individuals is very broad and includes Turner females, varying degrees of genital malformations, and men with normal phenotypes (3). The gonads of such patients have been reported as streak gonads, ovarian-like, and/or exhibiting other histopathological abnormalities in previous case reports, small studies, and large multicenter histological studies (4,5)
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