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Current understanding holds that Klinefelter syndrome (KS) is not inherited, but arises randomly during meiosis. Whether there is any genetic basis for the origin of KS is unknown. Here, guided by our identification of some USP26 variations apparently associated with KS, we found that knockout of Usp26 in male mice resulted in the production of 41, XXY offspring. USP26 protein is localized at the XY body, and the disruption of Usp26 causes incomplete sex chromosome pairing by destabilizing TEX11. The unpaired sex chromosomes then result in XY aneuploid spermatozoa. Consistent with our mouse results, a clinical study shows that some USP26 variations increase the proportion of XY aneuploid spermatozoa in fertile men, and we identified two families with KS offspring wherein the father of the KS patient harbored a USP26-mutated haplotype, further supporting that paternal USP26 mutation can cause KS offspring production. Thus, some KS should originate from XY spermatozoa, and paternal USP26 mutations increase the risk of producing KS offspring.

Tousled like kinase 1 (TLK1), a member of DNA repair family, participates in the regulation of chromatin assembly and is associated with early menopause and premature ovarian insufficiency (POI) in European women. However, whether the sequence variant in the TLK1 gene was causative for POI is still elusive. Here we performed direct sequencing of the TLK1 gene in 192 patients with sporadic POI. All exons and exon–intron boundaries of TLK1 were amplified and sequenced. Six known single-nucleotide polymorphisms were identified in POI, including rs149844334, rs11553951, rs757600673, rs2277339, rs113416007 and rs17283147. No novel variant was identified, which indicates that sequence variants in the coding region of TLK1 might be uncommon in Chinese women with POI. The role of TLK1 in POI pathogenesis needs to be further explored in larger cohorts from Chinese and other ethnic populations. [ABSTRACT FROM AUTHOR]

Purpose: The etiology of fertilization failure and polyspermy during assisted reproductive technology (ART) remains elusive. The aim of this study was to determine whether mutations in the IZUMO1 receptor (IZUMO1R) gene, which is essential for mammalian fertilization, contribute to the pathogenesis of fertilization failure or polyspermy in humans.Methods: We recruited 215 female subjects with fertilization failure/poor fertilization, 330 females with polyspermy, and 300 matched controls. All subjects underwent IVF treatment. Peripheral blood DNA of cases was extracted and screened for mutations in IZUMO1R gene.Results: Four rare single nucleotide polymorphisms (SNPs) of the IZUMO1R were identified among specimens from patients with fertilization failure and polyspermy but were absent in the 300 control subjects. These included a missense SNP (rs76779571 in exon 4), which was found in two fertilization failure patients, and a nonsynonymous SNP (rs61742524 in exon 1) and two synonymous SNPs (rs76781645 in exon 1 and rs377369966 in intron 2), which were found among three polyspermy cases.Conclusions: The variations in IZUMO1R might play a role in the pathogenesis of fertilization failure and polyspermy, and the putative functions and effects of these rare variants require further studies. [ABSTRACT FROM AUTHOR]

Background: To identify recurrent pregnancy loss (RPL)-related genetic variants in exons of TP53 gene in a population of Chinese Han women., Methods: This study is a case control study. The cases comprised 90 Chinese Han women with RPL. Another 90 women with at least one child and not more than one miscarriage were recruited as the controls. All exons of TP53 were amplified from genomic DNA and sequenced., Results: A total of five single-nucleotide polymorphisms (SNPs) were identified in both RPL and control women, namely rs1642785 G>C, rs1042522 G>C, rs4968187 G>A, rs17884306 G>A, and rs55817367 A>G. A significant difference was only observed for rs17884306 between cases and controls. The wild type G allele was associated with an increased risk of RPL. AA+GA genetic variants significantly decreased the risk of RPL compared with GG variant (odds ratio [OR] = 0.315, 95% confidence interval [CI]: 0.125 - 0.793, p = 0.014). Linkage disequilibrium exits between rs17884306 and rs1642785 and A-C double mutant haplotype showed significantly lower risk of RPL compared with G-G wild type haplotype (OR = 0.303, 95% CI: 0.117 - 0.786, p = 0.014). Model based-multifactor dimensionality reduction indicated that the influence of rs17884306 had interaction with the genotypes of four other loci (all p < 0.05). However, rs17884306 G>A did not cause amino acid substitution., Conclusions: Our study showed that rs17884306 c.826G>A was a novel polymorphism associated with RPL in Chinese Han women. Moreover, the influence of this SNP on RPL is not associated with p53 amino acid sequence.