[Genetic analysis and assisted reproductive guidance for two infertile patients with rare small supernumerary marker chromosomes]

OBJECTIVE

To carry out cytogenetic and molecular genetic analysis for two infertile patients carrying rare small supernumerary marker chromosomes (sSMC).

METHODS

Two infertile patients who received reproductive and genetic counseling at CITIC Xiangya Reproductive and Genetic Hospital on October 31, 2018 and May 10, 2021, respectively were selected as the study subjects. The origin of sSMCs was determined by conventional G banding, fluorescence in situ hybridization (FISH) and copy number variation sequencing (CNV-seq). Microdissection combined with high-throughput whole genome sequencing (MicroSeq) was carried out to determine the fragment size and genomic information of their sSMCs.

RESULTS

For patient 1, G-banded karyotyping and FISH revealed that he has a karyotype of mos47,XY,del(16)(p10p12),+mar[65]/46,XY,del(16)(p10p12)[6]/48,XY,del(16)(p10p12),+2mar[3].ish mar(Tel 16p-,Tel 16q-,CEP 16-,WCP 16+). CNV analysis has yielded a result of arr[GRCh37]16p12.1p11.2(24999364_33597595)×1[0.25]. MicroSeq revealed that his sSMC has contained the region of chromosome 16 between 24979733 and 34023115 (GRCh37). For patient 2, karyotyping and reverse FISH revealed that she has a karyotype of mos 47,XX,+mar[37]/46,XX[23].rev ish CEN5, and CNV analysis has yielded a result of seq[GRCh37]dup(5)(p12q11.2)chr5:g(45120001_56000000)dup[0.8]. MicroSeq results revealed that her sSMC has contained the region of chromosome 5 between 45132364 and 55967870(GRCh37). After genetic counseling, both couples had opted in vitro fertilization (IVF) treatment and preimplantation genetic testing (PGT).

CONCLUSION

For individuals harboring sSMCs, it is vital to delineate the origin and structural characteristics of the sSMCs for their genetic counseling and reproductive guidance. Preimplantation genetic testing after microdissection combined with high-throughput whole genome sequencing (MicroSeq-PGT) can provide an alternative treatment for carrier couples with a high genetic risk.

Evaluation of genetic risk of apparently balanced chromosomal rearrangement carriers by breakpoint characterization

PURPOSE

To report genetic characteristics and associated risk of chromosomal breaks due to chromosomal rearrangements in large samples.

METHODS

MicroSeq, a technique that combines chromosome microdissection and next-generation sequencing, was used to identify chromosomal breakpoints. Long-range PCR and Sanger sequencing were used to precisely characterize 100 breakpoints in 50 ABCR carriers.

RESULTS

In addition to the recurrent regions of balanced rearrangement breaks in 8q24.13, 11q11.23, and 22q11.21 that had been documented, we have discovered a 10-Mb region of 12q24.13-q24.3 that could potentially be a sparse region of balanced rearrangement breaks. We found that 898 breakpoints caused gene disruption and a total of 188 breakpoints interrupted genes recorded in OMIM. The percentage of breakpoints that disrupted autosomal dominant genes recorded in OMIM was 25.53% (48/188). Fifty-four of the precisely characterized breakpoints had 1-8-bp microhomologous sequences.

CONCLUSION

Our findings provide a reference for the evaluation of the pathogenicity of mutations in related genes that cause protein truncation in clinical practice. According to the characteristics of breakpoints, non-homologous end joining and microhomology-mediated break-induced replication may be the main mechanism for ABCRs formation.

Exploring the efficacy and beneficial population of preimplantation genetic testing for aneuploidy start from the oocyte retrieval cycle: a real-world study

BACKGROUND

Preimplantation genetic testing for aneuploidy (PGT-A) is widely used as an embryo selection technique in in vitro fertilization (IVF), but its effectiveness and potential beneficiary populations are unclear.

METHODS

This retrospective cohort study included patients who underwent their first oocyte retrieval cycles at CITIC-Xiangya between January 2016 and November 2019, and the associated fresh and thawed embryo transfer cycles up to November 30, 2020. PGT-A (PGT-A group) and intracytoplasmic sperm injection (ICSI)/IVF (non-PGT-A group) cycles were included. The numbers of oocytes and embryos obtained were unrestricted. In total, 60,580 patients were enrolled, and baseline data were matched between groups using 1:3 propensity score matching. Sensitivity analyses, including propensity score stratification and traditional multivariate logistic regression, were performed on the original unmatched cohort to check the robustness of the overall results. Analyses were stratified by age, body mass index, ovarian reserve/responsiveness, and potential indications to explore benefits in subgroups. The primary outcome was cumulative live birth rate (CLBR). The other outcomes included live birth rate (LBR), pregnancy loss rate, clinical pregnancy rate, pregnancy complications, low birth weight rate, and neonatal malformation rate.

RESULTS

In total, 4195 PGT-A users were matched with 10,140 non-PGT-A users. A significant reduction in CLBR was observed in women using PGT-A (27.5% vs. 31.1%; odds ratio (OR) = 0.84, 95% confidence interval (CI) 0.78-0.91; P < 0.001). However, women using PGT-A had higher first-transfer pregnancy (63.9% vs. 46.9%; OR = 2.01, 95% CI 1.81-2.23; P < 0.001) and LBR (52.6% vs. 34.2%, OR = 2.13, 95% CI 1.92-2.36; P < 0.001) rates and lower rates of early miscarriage (12.8% vs. 20.2%; OR = 0.58, 95% CI 0.48-0.70; P < 0.001), preterm birth (8.6% vs 17.3%; P < 0.001), and low birth weight (4.9% vs. 19.3%; P < 0.001). Moreover, subgroup analyses revealed that women aged ≥ 38 years, diagnosed with recurrent pregnancy loss or intrauterine adhesions benefited from PGT-A, with a significant increase in first-transfer LBR without a decrease in CLBR.

CONCLUSION

PGT-A does not increase and decrease CLBR per oocyte retrieval cycle; nonetheless, it is effective in infertile populations with specific indications. PGT-A reduces complications associated with multiple gestations.

Identification of a missense variant of MND1 in meiotic arrest and non-obstructive azoospermia

Meiotic arrest is a common pathologic phenotype of non-obstructive azoospermia (NOA), yet its genetic causes require further investigation. Meiotic nuclear divisions 1 (MND1) has been proved to be indispensable for meiotic recombination in many species. To date, only one variant of MND1 has been reported associated with primary ovarian insufficiency (POI), yet there has been no report of variants in MND1 associated with NOA. Herein, we identified a rare homozygous missense variant (NM_032117:c.G507C:p.W169C) of MND1 in two NOA-affected patients from one Chinese family. Histological analysis and immunohistochemistry demonstrated meiotic arrest at zygotene-like stage in prophase I and lack of spermatozoa in the proband's seminiferous tubules. In silico modeling demonstrated that this variant might cause possible conformational change in the leucine zippers 3 with capping helices (LZ3wCH) domain of MND1-HOP2 complex. Altogether, our study demonstrated that the MND1 variant (c.G507C) is likely responsible for human meiotic arrest and NOA. And our study provides new insights into the genetic etiology of NOA and mechanisms of homologous recombination repair in male meiosis.

Conventional IVF is feasible in preimplantation genetic testing for aneuploidy

PURPOSE

To investigate the feasibility of the application of conventional in vitro fertilization (cIVF) for couples undergoing preimplantation genetic testing for aneuploidies (PGT-A) with non-male factor infertility.

METHODS

To evaluate the efficiency of sperm whole-genome amplification (WGA), spermatozoa were subjected to three WGA protocols: Picoplex, ChromInst, and multiple displacement amplification (MDA). In the clinical studies, 641 couples who underwent PGT-A treatment for frozen embryos between January 2016 and December 2021 were included to retrospectively compare the chromosomal and clinical outcomes of cIVF and intracytoplasmic sperm injection (ICSI). Twenty-six couples were prospectively recruited for cIVF and PGT-A treatment between April 2021 and April 2022; parental contamination was analyzed in biopsied samples; and 12 aneuploid embryos were donated to validate the PGT-A results.

RESULTS

Sperm DNA failed to amplify under Picoplex and ChromInst conditions but could be amplified using MDA. In frozen PGT-A cycles, no significant differences in the average rates of euploid, mosaic, and aneuploid embryos per cycle between the cIVF-PGT-A and ICSI-PGT-A groups were observed. The results of the prospective study that recruited couples for cIVF-PGT-A treatment showed no paternal contamination and one case of maternal contamination in 150 biopsied trophectoderm samples. Among the 12 donated embryos with whole-chromosome aneuploidy, 11 (91.7%) presented uniform chromosomal aberrations, which were in agreement with the original biopsy results.

CONCLUSIONS

Under the Picoplex and ChromInst WGA protocols, the risk of parental contamination in the cIVF-PGT-A cycles was low. Therefore, applying cIVF to couples with non-male factor infertility who are undergoing PGT-A is feasible.

Dynein axonemal heavy chain 10 deficiency causes primary ciliary dyskinesia in humans and mice

Primary ciliary dyskinesia (PCD) is a congenital, motile ciliopathy with pleiotropic symptoms. Although nearly 50 causative genes have been identified, they only account for approximately 70% of definitive PCD cases. Dynein axonemal heavy chain 10 (DNAH10) encodes a subunit of the inner arm dynein heavy chain in motile cilia and sperm flagella. Based on the common axoneme structure of motile cilia and sperm flagella, DNAH10 variants are likely to cause PCD. Using exome sequencing, we identified a novel DNAH10 homozygous variant (c.589C > T, p.R197W) in a patient with PCD from a consanguineous family. The patient manifested sinusitis, bronchiectasis, situs inversus, and asthenoteratozoospermia. Immunostaining analysis showed the absence of DNAH10 and DNALI1 in the respiratory cilia, and transmission electron microscopy revealed strikingly disordered axoneme 9+2 architecture and inner dynein arm defects in the respiratory cilia and sperm flagella. Subsequently, animal models of Dnah10-knockin mice harboring missense variants and Dnah10-knockout mice recapitulated the phenotypes of PCD, including chronic respiratory infection, male infertility, and hydrocephalus. To the best of our knowledge, this study is the first to report DNAH10 deficiency related to PCD in human and mouse models, which suggests that DNAH10 recessive mutation is causative of PCD.

X-ray cross-complementing family: the bridge linking DNA damage repair and cancer

Genomic instability is a common hallmark of human tumours. As a carrier of genetic information, DNA is constantly threatened by various damaging factors that, if not repaired in time, can affect the transmission of genetic information and lead to cellular carcinogenesis. In response to these threats, cells have evolved a range of DNA damage response mechanisms, including DNA damage repair, to maintain genomic stability. The X-ray repair cross-complementary gene family (XRCC) comprises an important class of DNA damage repair genes that encode proteins that play important roles in DNA single-strand breakage and DNA base damage repair. The dysfunction of the XRCC gene family is associated with the development of various tumours. In the context of tumours, mutations in XRCC and its aberrant expression, result in abnormal DNA damage repair, thus contributing to the malignant progression of tumour cells. In this review, we summarise the significant roles played by XRCC in diverse tumour types. In addition, we discuss the correlation between the XRCC family members and tumour therapeutic sensitivity.

The effect of carrier characteristics and female age on preimplantation genetic testing results of blastocysts from Robertsonian translocation carriers

PURPOSE

To analyze factors affecting segregation and ploidy results from Robertsonian carriers, and determine chromosomes involved impact chromosome stability during meiosis and mitosis.

METHODS

This retrospective study include 928 oocyte retrieval cycles from 763 couples with Robertsonian translocations undergoing preimplantation genetic testing for structural rearrangements (PGT-SR) using next-generation sequencing (NGS) between December 2012 and June 2020.The segregation patterns of the trivalent of 3423 blastocysts were analyzed according to the carrier's sex and age. A total of 1492 couples who received preimplantation genetic testing for aneuploidy (PGT-A) were included as the control group and matched according to maternal age and testing time stage.

RESULTS

A total of 1728 (50.5%) normal/balanced embryos were identified from 3423 embryos diagnosed. The rate of alternate segregation in male Robertsonian translocation carriers was significantly higher than that in female carriers (82.3% vs. 60.0%, P < 0.001). However, the segregation ratio exhibited no difference between young and older carriers. Further, increasing maternal age decreased the proportion of transferable embryo cycle in both female and male carriers. And the ratio of chromosome mosaic from the Robertsonian translocation carrier group was significantly higher than that in the PGT-A control group (1.2% vs. 0.5%, P < 0.01).

CONCLUSIONS

The meiotic segregation modes were affected by the carrier sex and were independent of the carrier's age. Advanced maternal age decreased the probability of obtaining a normal/balanced embryo. In additional, the Robertsonian translocation chromosome could increase the possibility of chromosome mosaicism during mitosis in blastocysts.

Fat mass and obesity-associated factor (FTO)-mediated N6-methyladenosine regulates spermatogenesis in an age-dependent manner

N6-methyladenosine (m6A) is the most prevalent reversible RNA modification in the mammalian transcriptome. It has recently been demonstrated that m6A is crucial for male germline development. Fat mass and obesity-associated factor (FTO), a known m6A demethylase, is widely expressed in human and mouse tissues and is involved in manifold biological processes and human diseases. However, the function of FTO in spermatogenesis and male fertility remains poorly understood. Here, we generated an Fto knockout mouse model using CRISPR/Cas9-mediated genome editing techniques to address this knowledge gap. Remarkably, we found that loss of Fto in mice caused spermatogenesis defects in an age-dependent manner, resulting from the attenuated proliferation ability of undifferentiated spermatogonia and increased male germ cell apoptosis. Further research showed that FTO plays a vital role in the modulation of spermatogenesis and Leydig cell maturation by regulating the translation of the androgen receptor in an m6A-dependent manner. In addition, we identified two functional mutations of FTO in male infertility patients, resulting in truncated FTO protein and increased m6A modification in vitro. Our results highlight the crucial effects of FTO on spermatogonia and Leydig cells for the long-term maintenance of spermatogenesis and expand our understanding of the function of m6A in male fertility.

Ultra-low-coverage genome-wide association study-insights into gestational age using 17,844 embryo samples with preimplantation genetic testing

BACKGROUND

Very low-coverage (0.1 to 1×) whole genome sequencing (WGS) has become a promising and affordable approach to discover genomic variants of human populations for genome-wide association study (GWAS). To support genetic screening using preimplantation genetic testing (PGT) in a large population, the sequencing coverage goes below 0.1× to an ultra-low level. However, the feasibility and effectiveness of ultra-low-coverage WGS (ulcWGS) for GWAS remains undetermined.

METHODS

We built a pipeline to carry out analysis of ulcWGS data for GWAS. To examine its effectiveness, we benchmarked the accuracy of genotype imputation at the combination of different coverages below 0.1× and sample sizes from 2000 to 16,000, using 17,844 embryo PGT samples with approximately 0.04× average coverage and the standard Chinese sample HG005 with known genotypes. We then applied the imputed genotypes of 1744 transferred embryos who have gestational ages and complete follow-up records to GWAS.

RESULTS

The accuracy of genotype imputation under ultra-low coverage can be improved by increasing the sample size and applying a set of filters. From 1744 born embryos, we identified 11 genomic risk loci associated with gestational ages and 166 genes mapped to these loci according to positional, expression quantitative trait locus, and chromatin interaction strategies. Among these mapped genes, CRHBP, ICAM1, and OXTR were more frequently reported as preterm birth related. By joint analysis of gene expression data from previous studies, we constructed interrelationships of mainly CRHBP, ICAM1, PLAGL1, DNMT1, CNTLN, DKK1, and EGR2 with preterm birth, infant disease, and breast cancer.

CONCLUSIONS

This study not only demonstrates that ulcWGS could achieve relatively high accuracy of adequate genotype imputation and is capable of GWAS, but also provides insights into the associations between gestational age and genetic variations of the fetal embryos from Chinese population.

Bi-allelic human TEKT3 mutations cause male infertility with oligoasthenoteratozoospermia due to acrosomal hypoplasia and reduced progressive motility

Oligoasthenoteratozoospermia (OAT) can result in male infertility due to reduced sperm motility and abnormal spermatozoan morphology. The Tektins are a family of highly conserved filamentous proteins expressed in the axoneme and associated structures in many different metazoan species. Earlier studies on mice identified Tektin3 (Tekt3) as a testis-enriched gene, and knockout of Tekt3 resulted in asthenozoospermia in the mice. Here, whole exome sequencing of 100 males with asthenozoospermia from unrelated families was performed, followed by Sanger sequencing, leading to the identification of TEKT3 as a candidate gene in two of these patients and their associated family members. In total, three mutations in the TEKT3 gene were identified in both these patients, including one homozygous deletion-insertion mutation (c.543_547delinsTTGAT: p.Glu182*) and one compound heterozygous mutation (c.[548G > A]; [752A > C], p.[(Arg183Gln)]; [(Gln251Pro)]). Both of these mutations resulted in the complete loss of TEKT3 expression. The patients were both found to produce sperm that, although they showed no apparent defects in the flagellar structure, had reduced progressive motility. In contrast to mice, most sperm from these two patients exhibited acrosomal hypoplasia, although this did not prevent the use of the sperm for in vitro fertilization through an ICSI approach. TEKT3 was found to bind to other TEKT proteins, suggesting that these proteins form a complex within human spermatozoa. Overall, these results suggest that a loss of TEKT3 function can contribute to OAT incidence in humans. TEKT3 deficiencies can reduce sperm motility and contribute to severe acrosomal hypoplasia in spermatozoa, compromising their normal function.

IQCN disruption causes fertilization failure and male infertility due to manchette assembly defect

Total fertilization failure (TFF) is an important cause of infertility; however, the genetic basis of TFF caused by male factors remains to be clarified. In this study, whole-exome sequencing was firstly used to screen for genetic causes of TFF after intracytoplasmic sperm injection (ICSI), and homozygous variants in the novel gene IQ motif-containing N (IQCN) were identified in two affected individuals with abnormal acrosome structures. Then, Iqcn-knockout mice were generated by CRISPR-Cas9 technology and showed that the knockout male mice resembled the human phenotypes. Additionally, we found that IQCN regulates microtubule nucleation during manchette assembly via calmodulin and related calmodulin-binding proteins, which resulted in head deformity with aberrant oocyte activation factor PLCζ. Fortunately, ICSI with assisted oocyte activation can overcome IQCN-associate TFF and male infertility. Thus, our study firstly identified the function of IQCN, highlights the relationship between the manchette assembly and fertilization, and provides a genetic marker and a therapeutic option for male-source TFF.

Reclassification of DMD Duplications as Benign: Recommendations for Cautious Interpretation of Variants Identified in Prenatal Screening

Duplications are the main type of dystrophin gene (DMD) variants, which typically cause dystrophinopathies such as Duchenne muscular dystrophy and Becker muscular dystrophy. Maternally inherited exon duplication in DMD in fetuses is a relatively common finding of genetic screening in clinical practice. However, there is no standard strategy for interpretation of the pathogenicity of DMD duplications during prenatal screening, especially for male fetuses, in which maternally inherited pathogenic DMD variants more frequently cause dystrophinopathies. Here, we report three non-contiguous DMD duplications identified in a woman and her male fetus during prenatal screening. Multiplex ligation probe amplification and long-read sequencing were performed on the woman and her family members to verify the presence of DMD duplications. Structural rearrangements in the DMD gene were mapped by long-read sequencing, and the breakpoint junction sequences were validated using Sanger sequencing. The woman and her father carried three non-contiguous DMD duplications. Long-read and Sanger sequencing revealed that the woman's father carried an intact DMD copy and a complex structural rearrangement of the DMD gene. Therefore, we reclassified these three non-contiguous DMD duplications, one of which is listed as pathogenic, as benign. We postulate that breakpoint analysis should be performed on identified DMD duplication variants, and the pathogenicity of the duplications found during prenatal screening should be interpreted cautiously for clinical prediction and genetic/reproductive counseling.

[Genetic testing and prenatal diagnosis of 671 Chinese pedigrees affected with Duchenne/Becker muscular dystrophy]

OBJECTIVE

To summarize the genetic characteristics of 671 Chinese pedigrees affected with Duchenne/Becker muscular dystrophy (DMD/BMD).

METHODS

Clinical data of the pedigrees were collected. Multiplex PCR, multiple ligation dependent probe amplification (MLPA), next generation sequencing (NGS), Sanger sequencing and long read sequencing were used to detect the variant of DMD gene in the probands and their mothers, and prenatal diagnosis was provided for high risk pregnant women.

RESULTS

Among 178 pedigrees analyzed by multiplex PCR, 44 variants of the DMD gene were detected, with the genetic diagnosis attained in 110 pedigrees. Among 493 pedigrees analyzed by MLPA in combination with NGS or Sanger sequencing, 294 pathogenic/possible pathogenic variants were identified, among which 45 were unreported previously, and the genetic diagnosis attained in 484 pedigrees. Structural variants of the DMD gene were identified in two pedigrees by long-read sequencing. Among 444 probands, 341 have inherited the DMD gene variant from their mothers (76.8%). Among 390 women with a high-risk, 339 have opted to have natural pregnancy and 51 chose preimplantation genetic testing for monogenetic disease (PGT-M). The detection rate of neonatal patients and carriers following natural pregnancy was significantly higher than that for PGT-M.

CONCLUSION

Combined application of MLPA, NGS, Sanger sequencing and long-read sequencing is an effective strategy to detect DMD/BMD. PGT-M can effectively reduce the risk of fetuses. Above finding has expanded the spectrum of DMD gene variants and provided a basis for reproductive intervention for pregnancies with a high risk for DMD/BMD.

A novel multifunctional haplotyping-based preimplantation genetic testing for different genetic conditions

STUDY QUESTION

Is there an efficient and cost-effective detection platform for different genetic conditions about embryos?

SUMMARY ANSWER

A multifunctional haplotyping-based preimplantation genetic testing platform was provided for detecting different genetic conditions.

WHAT IS KNOWN ALREADY

Genetic disease and chromosomal rearrangement have been known to significantly impact fertility and development. Therefore, preimplantation genetic testing for aneuploidy (PGT-A), monogenic disorders (PGT-M) and structural rearrangements (PGT-SR), a part of ART, has been presented together to minimize the fetal genetic risk and increase pregnancy rate. For patients or their families who are suffering from chromosome abnormality, monogenic disease, unexplained repeated spontaneous abortion or implantation failure, after accepting genetic counseling, they may be suggested to accept detection from more than one PGT platforms about the embryos to avoid some genetic diseases. However, PGT platforms work through different workflows. The high costliness, lack of material and long-time operation of combined PGT platforms limit their application.

STUDY DESIGN, SIZE, DURATION

All 188 embryonic samples from 43 families were tested with HaploPGT platform, and most of their genetic abnormalities had been determined by different conventional PGT methods beforehand. Among them, there were 12 families only carrying structural rearrangements (115 embryos) in which 9 families accepted implantation and 5 families had normal labor ART outcomes, 7 families only carrying monogenic diseases (26 embryos) and 3 families carrying both structural rearrangements and monogenic diseases (26 embryos). Twelve monopronucleated zygotes (1PN) samples and 9 suspected triploid samples were collected from 21 families.

PARTICIPANTS/MATERIALS, SETTINGS, METHODS

Here, we raised a comprehensive PGT method called HaploPGT, combining reduced representation genome sequencing, read-count analysis, B allele frequency and haplotyping analysis, to simultaneously detect different genetic disorders in one single test.

MAIN RESULTS AND THE ROLE OF CHANCE

With 80 million reads (80M) genomic data, the proportion of windows (1 million base pairs (Mb)) containing two or more informative single nucleotide polymorphism (SNP) sites was 97.81%, meanwhile the genotyping error rate stabilized at a low level (2.19%). Furthermore, the informative SNPs were equally distributed across the genome, and whole-genomic haplotyping was established. Therefore, 80M was chosen to balance the cost and accuracy in HaploPGT. HaploPGT was able to identify abnormal embryos with triploid, global and partial loss of heterozygosity, and even to distinguish parental origin of copy number variation in mosaic and non-mosaic embryos. Besides, by retrospectively analyzing 188 embryonic samples from 43 families, HaploPGT revealed 100% concordance with the available results obtained from reference methods, including PGT-A, PGT-M, PGT-SR and PGT-HLA.

LIMITATIONS, REASON FOR CAUTION

Despite the numerous benefits HaploPGT could bring, it still required additional family members to deduce the parental haplotype for identifying balanced translocation and monogenic mutation in tested embryos. In terms of PGT-SR, the additional family member could be a reference embryo with unbalanced translocation. For PGT-M, a proband was normally required. In both cases, genomic information from grandparents or parental siblings might help for haplotyping theoretically. Another restriction was that haploid, and diploid resulting from the duplication of a haploid, could not be told apart by HaploPGT, but it was able to recognize partial loss of heterozygosity in the embryonic genome. In addition, it should be noted that the location of rearrangement breakpoints and the situation of mutation sites were complicated, which meant that partial genetic disorders might not be completely detected.

WIDER IMPLICATIONS OF THE FINDINGS

HaploPGT is an efficient and cost-effective detection platform with high clinical value for detecting genetic status. This platform could promote the application of PGT in ART, to increase pregnancy rate and decrease the birth of children with genetic diseases.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by grants from the National Natural Science Foundation of China (81873478, to L.H.), National Key R&D Program of China (2018YFC1003100, to L.H.), the Natural Science Foundation of Hunan Province (Grant 2022JJ30414, to P.X.), Hunan Provincial Grant for Innovative Province Construction (2019SK4012) and the Scientific Research Foundation of Reproductive and Genetic Hospital of China International Trust & Investment Corporation (CITIC)-Xiangya (YNXM-201910). Haplotyping analysis has been licensed to Basecare Co., Ltd. L.K., Y.M., K.K., D.Z., N.L., J.Z. and R.D. are Basecare Co., Ltd employees. The other authors declare no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

P-524 Bi-allelic CFAP61 variants cause male infertility in humans and mice with severe oligoasthenoteratozoospermia

Study question

Are mutations in cilia and flagella-associated protein 61 (CFAP61) associated with human male infertility?

Summary answer

Bi-allelic variants ([NM_015585.4: c.1654C&gt;T (p.R552C) and c.2911G&gt;A (p.D971N), c.144-2A&gt;G and c.1666G&gt;A (p.G556R)] in CFAP61 were identified as contributory genetics factor in severe oligoasthenoteratozoospermia (OAT).

What is known already

Cfap61 knockout mice were infertile due to multiple morphological abnormalities of the sperm flagella (MMAF). However, so far there is no direct evidence that mutations of CFAP61 cause OAT and male infertility.

Study design, size, duration

Variant screening was performed by whole-exome sequencing (WES) from 325 infertile patients with OAT and 392 fertile individuals. A knockout mouse model was generate to confirm the candidate disease-causing gene, intracytoplasmic sperm injection (ICSI) was used to evaluate the efficiency of clinical treatment.

Participants/materials, setting, methods

A total 325 OAT-affected patients and 392 men with normal fertility were recruited from China. WES was performed, followed by Sanger sequencing validation. In silico bioinformatics predictions and in vitro functional analyses were performed to evaluate the impacts of candidate disease-causing variants. Hematoxylin and eosin (H&E) staining, electron microscopy, and immunofluorescence assays were performed to evaluate the sperm morphology. Two OAT-affected men with CFAP61 variants were treated by ICSI, and pregnancy outcomes were followed.

Main results and the role of chance

We identified bi-allelic CFAP61 variants [NM_015585.4: c.1654C&gt;T (p.R552C) and c.2911G&gt;A (p.D971N), c.144-2A&gt;G and c.1666G&gt;A (p.G556R)] in two (0.62%) of the 325 OAT-affected men. In silico bioinformatics analysis predicted that all four variants were deleterious, and in vitro functional analysis confirmed the deleterious effects of the mutants. Notably, H&E staining and electron microscopy analyses of the spermatozoa revealed multiple morphological abnormalities of sperm flagella, the absence of central pair microtubules, and mitochondrial sheath malformation in sperm flagella from man with CFAP61 variants. Further immunofluorescence assays revealed markedly reduced CFAP61 staining in the sperm flagella. In addition, Cfap61-deficient mice showed the OAT phenotype, suggesting that loss of function of CFAP61 was the cause of OAT. Two individuals accepted ICSI therapy using their own ejaculated sperm, and one of them succeeded in fathering a healthy baby.

Limitations, reasons for caution

Limitations include the lack of in vivo data from the one of patients, and the exact molecular mechanism should be further investigated.

Wider implications of the findings

Our findings indicate that CFAP61 is essential for spermatogenesis and that bi-allelic CFAP61 variants lead to OAT and male infertility in humans and mice. In addition, our results show that ICSI treatment can be recommended for CFAP61-related OAT.

Trial registration number

not applicable

Risk Factors Affecting Alternate Segregation in Blastocysts From Preimplantation Genetic Testing Cycles of Autosomal Reciprocal Translocations

Reciprocal translocations are the most common structural chromosome rearrangements and may be associated with reproductive problems. Therefore, the objective of this study was to analyze factors that can influence meiotic segregation patterns in blastocysts for reciprocal translocation carriers. Segregation patterns of quadrivalents in 10,846 blastocysts from 2,871 preimplantation genetic testing cycles of reciprocal translocation carriers were analyzed. The percentage of normal/balanced blastocysts was 34.3%, and 2:2 segregation was observed in 90.0% of the blastocysts. Increased TAR1 (ratio of translocated segment 1 over the chromosome arm) emerged as an independent protective factor associated with an increase in alternate segregation (p = 0.004). Female sex and involvement of an acrocentric chromosome (Acr-ch) were independent risk factors that reduced alternate segregation proportions (p < 0.001). Notably, a higher TAR1 reduced the proportion of adjacent-1 segregation (p < 0.001); a longer translocated segment and female sex increased the risk of adjacent-2 segregation (p = 0.009 and p < 0.001, respectively). Female sex and involvement of an Acr-ch enhanced the ratio of 3:1 segregation (p < 0.001 and p = 0.012, respectively). In conclusion, autosomal reciprocal translocation carriers have reduced proportions of alternate segregation in blastocysts upon the involvement of an Acr-ch, female sex, and lower TAR1. These results may facilitate more appropriate genetic counseling for couples with autosomal reciprocal translocation regarding their chances of producing normal/balanced blastocysts.

[Pre-conception carrier screening for 21 inherited metabolic diseases in a Chinese population]

OBJECTIVE

To determine the carrier rate for 21 inherited metabolic diseases among a Chinese population of childbearing age.

METHODS

A total of 897 unrelated healthy individuals (including 143 couples) were recruited, and DNA was extracted from their peripheral blood samples. Whole exome sequencing (WES) was carried out to screen potential variants among 54 genes associated with 21 inherited metabolic diseases. Pathogenic and likely pathogenic variants and unreported loss-of-function variants were analyzed.

RESULTS

One hundred fourty types of pathogenic/likely pathogenic variants (with an overall number of 183) and unreported loss-of-function variants were detected, which yield a frequency of 0.20 per capita. A husband and wife were both found to carry pathogenic variants of the SLC25A13 gene and have given birth to a healthy baby with the aid of preimplantation genetic diagnosis. The detected variants have involved 40 genes, with the most common ones including ATP7B, SLC25A13, PAH, CBS and MMACHC. Based on the Hardy-Weinberg equilibrium, the incidence of the 21 inherited metabolic diseases in the population was approximately 1/1100, with the five diseases with higher incidence including citrullinemia, methylmalonic acidemia, Wilson disease, glycogen storage disease, and phenylketonuria.

CONCLUSION

This study has preliminarily determined the carrier rate and incidence of 21 inherited metabolic diseases among a Chinese population of childbearing age, which has provided valuable information for the design of neonatal screening program for inherited metabolic diseases. Pre-conception carrier screening can provide an important measure for the prevention of transmission of Mendelian disorders in the population.

Deleterious variants in TAF7L cause human oligoasthenoteratozoospermia and its impairing histone to protamine exchange inducing reduced in vitro fertilization

INTRODUCTION

Oligoasthenoteratozoospermia (OAT) is a major cause of infertility in males. Only a few pathogenic genes of OAT have been clearly identified till now. A large number of OAT-affected cases remain largely unknown.

METHODS

Here, Whole-exome sequencing (WES) in 725 idiopathic OAT patients was performed. Ejaculated spermatozoa by OAT patients were microinjected into mouse oocytes to estimate fertilization potential. Diff-quick staining and transmission electron microscopy were performed to evaluate sperm morphology and ultrastructure. The protein expression level and localization In vitro were detected by Western Blotting and Immunocytochemistry.

RESULTS

We identified four X-linked hemizygous deleterious variants of TAF7L-namely, c.1301_1302del;(p.V434Afs*5), c.699G>T;(p.R233S), c.508delA; (p. T170fs), c.719dupA;(p.K240fs) -in five probands. Intracytoplasmic sperm injection (ICSI) were carried out in M1, M2-1and M3 patient's wife. However only M1 patient's wife became pregnant after embryo transfer. In vitro study demonstrated significantly reduced fertilization ability in patient with TAF7L mutation. The TAF7L mutation let to abnormal sperm head and impaired histone-to protamine exchange. Variant 719dupA (p. K240fs) resulted in producing a truncated TAF7L protein and localized massively within the nucleus. In addition, TAF7L expression were not able to be detected due to variants c.1301_1302del (p. V434Afs*5) and c.508delA (p. T170fs) In vitro.

CONCLUSION

Our findings support that TAF7L is one of pathogenic genes of OAT and deleterious mutations in TAF7L may cause impaired histone-to-protamine affected the chromatin compaction of sperm head.

Loss-of-function missense variant of AKAP4 induced male infertility through reduced interaction with QRICH2 during sperm flagella development

Sperm fibrous sheath is closely related to sperm maturation, capacitation and motility, and A-kinase anchor protein 4 (AKAP4) is the most abundant protein in sperm fibrous sheath. Previous studies found incomplete sperm fibrous sheaths and abnormal flagella in Akap4 knockout (KO) mice. Meanwhile, it was reported that the partial deletion in AKAP4 is highly relevant to the dysplasia of the fibrous sheath in an infertile man, and so far, there is no report about male infertility caused by hemizygous AKAP4 variant. Furthermore, the specific mechanisms of how the variant is relevant to the phenotype remain elusive. In this study, we investigated three multiple morphological abnormalities of the sperm flagella (MMAF)-affected men from three independent families (including one consanguine family) carried hemizygous c.C1285T variant in AKAP4. The patients carried thisvariant showed dysplastic sperm fibrous sheath and the protein expression of AKAP4 was decreased in flagella which was further confirmed in HEK-293 T cells in vitro. In addition, the co-localization and interaction between AKAP4 and glutamine-rich protein 2 (QRICH2) on the molecular level were identified by immunofluorescence and Co-immunoprecipitation (CO-IP). The hemizygous c.1285C > T variant in AKAP4 induced decreased protein expression of QRICH2 in spermatozoa. These results suggested that the normal expression of AKAP4 is required for maintaining the expression of QRICH2 and the decreased protein expression of AKAP4 and QRICH2，as well as the interaction between them induced by the hemizygous variant of AKAP4 caused dysplastic fibrous sheath, which eventually led to reduced sperm motility and male infertility.

Integrated analysis of high-throughput sequencing data reveals the key role of LINC00467 in the invasion and metastasis of testicular germ cell tumors

Long noncoding RNAs (lncRNAs) are involved in various physiological and pathological processes. However, the role of lncRNAs in testicular germ cell tumor (TGCT) has been rarely reported. Our purpose is to comprehensively survey the expression and function of lncRNAs in TGCT. In this study, we used RNA sequencing to construct the lncRNA expression profiles of 13 TGCT tissues and 4 paraneoplastic tissues to explore the function of lncRNAs in TGCT. The bioinformatics analysis showed that many lncRNAs are differentially expressed in TGCT. GO and KEGG enrichment analyses revealed that the differentially expressed lncRNAs participated in various biological processes associated with tumorigenesis in cis and trans manners. Further, we found that the expression of LINC00467 was positively correlated with the poor prognosis and pathological grade of TGCT using WGCNA analysis and GEPIA database data mining. In vitro experiments revealed that LNC00467 could promote the migration and invasion of TGCT cells by regulating the expression of AKT3 and influencing total AKT phosphorylation. Further analysis of TCGA data revealed that the expression was negatively correlated with the infiltration of immune cells and the response to PD1 immunotherapy. In summary, this study is the first to construct the expression profile of lncRNAs in TGCT. It is also the first study to identify the metastasis-promoting role of LNC00467, which can be used as a potential predictor of TGCT prognosis and immunotherapeutic response to provide a clinical reference for the treatment and diagnosis of TGCT metastasis.

The Setup and Application of Reference Material in Sequencing-Based Noninvasive Prenatal Testing

INTRODUCTION

The sequencing-based noninvasive prenatal testing (NIPT) has been successfully integrated into clinical practice and facilitated the early detection of fetal chromosomal anomalies. However, a comprehensive reference material to evaluate and quality control NIPT services from different NIPT providers remains unavailable.

METHODS

In this study, we established a set of NIPT reference material consisting of 192 simulated samples. Most of the potential factors influencing the accuracy of NIPT, such as fetal fraction, mosaicism, and interfering substances, were included in the reference material. We compared the performance of chromosomal abnormalities detection on 3 widely used sequencers (NextSeq 500, BGISEQ-500, and Ion Proton) based on the reference material.

RESULTS

All 3 sequencers provided highly accurate and reliable results to samples with ≥3.5% fetal fractions and high percentage of mosaicism.

CONCLUSIONS

The established reference material can serve as a universal standard quality control for the current and new-coming NIPT providers based on various sequencers.

Preimplantation genetic testing results of blastocysts from 12 non-Robertsonian translocation carriers with chromosome fusion and comparison with Robertsonian translocation carriers

OBJECTIVE

To investigate the effects of non-Robertsonian translocation with chromosome fusion (N-RBCF) on preimplantation embryos.

DESIGN

Case series.

SETTING

University-affiliated center.

PATIENT(S)

Twelve couples with N-RBCF.

INTERVENTION(S)

Assisted reproduction with preimplantation genetic testing in chromosomal structural rearrangement (PGT-SR).

MAIN OUTCOME MEASURE(S)

Normal embryo rate, unbalanced translocation rate.

RESULT(S)

PGT was performed in 12 N-RBCF carriers, of whom 4 carried Y-autosome fusions and 8 autosomal fusions. A total of 12 (63.2%) of 19 blastocysts exhibited normal/balanced embryos, and only one (5.3%) embryo exhibited unbalanced translocations among Y-autosome fusion cases. In contrast to these findings, the percentage of normal/balanced blastocysts in 8 autosomal N-RBCF cases was 28.2% (11/39), whereas the unbalanced translocation rate was 53.8%. Furthermore, the percentage of normal/balanced embryos in the Robertsonian translocation group was significantly higher than that of the 8 autosomal N-RBCF (48.7% vs. 28.2%) cases. The rates of abnormality from chromosomal fusion in the 8 autosomal N-RBCF cases were significantly higher than those noted in the Robertsonian translocation (53.8% vs. 31.4%) subjects. The results of the stratified analysis according to the carrier's sex demonstrated that the rates of unbalanced translocation were significantly higher in the male autosomal N-RBCF subjects than those from the corresponding Robertsonian translocation (55% vs. 19.7%) cases.

CONCLUSION(S)

A low number of unbalanced translocations was identified in blastocysts from N-RBCF subjects who carried the Y fusion. The risk of unbalanced translocation in autosomal N-RBCF was higher than that of the Robertsonian translocation, notably in male carriers.

Long noncoding RNAs expression profile and long noncoding RNA-mediated competing endogenous RNA network in nonobstructive azoospermia patients

Aim: To analyze the expression profile and competing endogenous RNA (ceRNA) network of long noncoding RNAs (lncRNAs) in nonobstructive azoospermia (NOA). Materials & methods: The lncRNA expression profile in NOA was determined by microarray reanalysis. Differential expression analysis was performed by R software. The ceRNA network was constructed using correlation analysis and gene target miRNA prediction. Metascape was used for enrichment analysis. Again ceRNA network was validated by quantitative real-time PCR. Results: Many lncRNAs are differently expressed in NOA. LncRNAs might participate in spermatogenesis through ceRNA mechanism. The ceRNA network included male gamete generation and other pathways. LINC00467 in the network regulated the expression of LRGUK and TDRD6. Conclusion: LncRNAs are involved in NOA and potential biomarkers and therapeutic targets for NOA.

Testicular biopsies microarray analysis reveals circRNAs are involved in the pathogenesis of non-obstructive azoospermia

Circular RNAs (circRNAs) have been reported to be involved in many diseases. But there is no report on circRNAs in non-obstructive azoospermia (NOA). The purpose of this paper is to explore the circular RNA expression profile and potential functions of circRNAs in NOA patients. We first preformed circRNA expression profiling analysis using a circRNA microarray in testicular samples from NOA and obstructive azoospermia (OA) patients. CircRNAs were validated by qRT-PCR. Bioinformatics analysis were used to construct the ceRNA network. GO and KEGG enrichment analysis were performed by using DAVID. Microarray analysis identified 82 differentially expressed circRNAs in NOA specimens. The differential expression of hsa_circRNA_402130, hsa_circRNA_072697, hsa_circRNA_030050, hsa_circRNA_100812 and hsa_circRNA_406168 was confirmed by qRT-PCR. Enrichment analysis revealed the association of hsa_circRNA_402130 and hsa_circRNA_072697 with multiple signaling pathways. The data indicated that circRNAs were significantly dysregulated in NOA specimens and might involve in the pathogenesis of NOA.

Location of Balanced Chromosome-Translocation Breakpoints by Long-Read Sequencing on the Oxford Nanopore Platform

Genomic structural variants, including translocations, inversions, insertions, deletions, and duplications, are challenging to be reliably detected by traditional genomic technologies. In particular, balanced translocations and inversions can neither be identified by microarrays since they do not alter chromosome copy numbers, nor by short-read sequencing because of the unmappability of short reads against repetitive genomic regions. The precise localization of breakpoints is vital for exploring genetic causes in patients with balanced translocations or inversions. Long-read sequencing techniques may detect these structural variants in a more direct, efficient, and accurate manner. Here, we performed whole-genome, long-read sequencing using the Oxford Nanopore GridION sequencer to detect breakpoints in six balanced chromosome translocation carriers and one inversion carrier. The results showed that all the breakpoints were consistent with the karyotype results with only ~10× coverage. Polymerase chain reaction (PCR) and Sanger sequencing confirmed 8 out of 14 breakpoints; however, other breakpoint loci were slightly missed since they were either in highly repetitive regions or pericentromeric regions. Some of the breakpoints interrupted normal gene structure, and in other cases, micro-deletions/insertions were found just next to the breakpoints. We also detected haplotypes around the breakpoint regions. Our results suggest that long-read, whole-genome sequencing is an ideal strategy for precisely localizing translocation breakpoints and providing haplotype information, which is essential for medical genetics and preimplantation genetic testing.

The expression characteristics of FBXW7 in human testis suggest its function is different from that in mice

F-box and WD domain protein 7 (FBXW7) is reported to bind with c-Myc in mouse spermatogonial stem cells, regulating self-renewal; however, the pattern and stage of expression of FBXW7 in human testes are unclear. In the present study, we examined the expression of human FBXW7 in adult testis, and analyzed fixed sections from adult testes and fetal testes to determine the cell type-specific expression pattern of FBXW7. The results showed that FBXW7α and FBXW7β genes are expressed in the testis; however, only FBXW7α protein could be detected. FBXW7 was not detected in human spermatogonial stem cells. Interestingly, FBXW7 was mainly expressed in the cell nuclei of later stage germ cells and differentiated somatic cells. We also observed high FBXW7 expression in human fetal germ cells, particularly in prespermatogonia. Our results raised the possibility that FBXW7 has different functions in humans and mice. The cell type-specific expression pattern of FBXW7 suggests that it performs regulatory functions during the late stage of human spermatogenesis instead of being involved in the self-renewal of spermatogonial stem cells.

Retrospective analysis of meiotic segregation pattern and interchromosomal effects in blastocysts from inversion preimplantation genetic testing cycles

OBJECTIVE

To determine factors affecting unbalanced chromosomal rearrangement originating from parental inversion and interchromosomal effect occurrence in blastocysts from inversion carriers.

DESIGN

Retrospective study.

SETTING

University-affiliated center.

PATIENT(S)

Couples with one partner carrying inversion underwent preimplantation genetic testing for chromosomal structural rearrangement cycles.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE(S)

Unbalanced rearrangement embryo rate, normal embryo rate, interchromosomal effect.

RESULT(S)

Preimplantation genetic testing was performed for 576 blastocysts from 57 paracentric (PAI) and 94 pericentric (PEI) inversion carriers. The percentage of normal/balanced blastocysts was significantly higher in PAI than PEI carriers (70.4% vs. 57.5%). Logistic regression indicated the inverted segment size ratio was a statistically significant risk factor for abnormality from parental inversion in both PEI and PAI. The optimal cutoff values to predict unbalanced rearrangement risk were 35.7% and 57%. In PAI, rates of abnormality from parental inversion were 0% and 12.1% in the <35.7% and ≥35.7% groups, respectively, with no gender difference. For PEI, the rates of abnormality from parental inversion were 7.9% and 33.1% in the <57% and ≥57% groups, respectively. In the ≥57% group, the rate of unbalanced rearrangement was significantly higher from paternal than maternal inversion (43.3% vs. 23.6%). In inversion carriers, 21,208 chromosomes were examined, and 187 (0.88%) malsegregations were identified from structurally normal chromosomes. In controls, 56,488 chromosomes were assessed, and 497 (0.88%) aneuploidies were identified, indicating no significant difference.

CONCLUSION(S)

The risk of unbalanced rearrangement is affected by the ratio of inverted segment size in both PAI and PEI carriers and is associated with gender.

Boron carbide composites with highly aligned graphene nanoplatelets: light-weight and efficient electromagnetic interference shielding materials at high temperatures

B₄C-based ceramic composites containing 0-2 vol% highly aligned graphene nanoplatelets (GNPs) are fabricated. The electromagnetic interference (EMI) shielding properties of the obtained composites are investigated at X-band (8.2-12.4 GHz) frequency range from room-temperature up to 800 °C. All composites exhibit outstanding EMI shielding properties with satisfactory frequency- and thermal-stability. The shielding effectiveness (SE) of GNP/B₄C composites increases monotonically with increasing GNP loading. Superior room-temperature SE close to 40 dB is achieved with only 2 vol% GNPs and high SE around 35 dB still persists at 800 °C. Considering their relatively low density, GNP/B₄C composites possess a high specific shielding effectiveness (SSE) of 16 dB cm³ g^-1 which is among the highest values in reported ceramic-based shielding composites. Especially, the GNP/B₄C composite with 2 vol% GNPs exhibits the highest SSE/t (SSE divided by thickness) values at temperatures above 200 °C for all reported shielding composites, indicating that GNP/B₄C composites belong to the most promising high-temperature shielding composites. The excellent shielding properties of GNP/B₄C composites arise mainly from the high electrical conductivity, high dielectric loss and the multiple reflections by the highly aligned and large-sized GNP layers.

Prevalence and authenticity of de-novo segmental aneuploidy (>16 Mb) in human blastocysts as detected by next-generation sequencing

RESEARCH QUESTION

What is the prevalence and authenticity of de-novo segmental aneuploidies (>16 Mb) detected by next-generation sequencing (NGS) in human preimplantation blastocysts?

DESIGN

Between April 2013 and June 2016, 5735 blastocysts from 1854 couples (average age 33.11 ± 5.65 years) underwent preimplantation genetic testing for chromosomal structural rearrangement (PGT-SR) or for aneuploidy (PGT-A) using NGS on trophectoderm (TE) biopsy samples. The prevalence of de-novo segmental aneuploidy was calculated from these results. Forty blastocysts with de-novo segmental aneuploidy detected by NGS, which had been donated for research, were warmed for further fluorescence in-situ hybridization (FISH) analysis to confirm their authenticity.

RESULTS

The frequency of de-novo segmental aneuploidies in blastocysts was 10.13% (581/5735); the phenomenon was not related to maternal age and occurred on all chromosomes. Of the 40 donated blastocysts, 39 were successfully warmed and fixed for FISH analysis at the single-cell level. The de-novo segmental aneuploidies identified by NGS were confirmed by FISH in all 39 blastocysts. However, the de-novo segmental aneuploidies in these blastocysts were not all pure patterns, with 66.67% (26/39) of blastocysts exhibiting mosaic patterns varying from 8.30% to 92.86% of cells with de-novo segmental aneuploidy. The concordance rate between NGS and FISH in TE and inner cell mass (ICM) samples was 47.69% (31/65).

CONCLUSIONS

De-novo segmental aneuploidy above 16 Mb occurred in blastocysts and could be detected by NGS, while some aneuploidies existed as mosaics in both TE and ICM.

ZP2 pathogenic variants cause in vitro fertilization failure and female infertility

PURPOSE

The oocyte-borne genetic causes leading to fertilization failure are largely unknown. We aimed to identify novel human pathogenic variants (PV) and genes causing fertilization failure.

METHODS

We performed exome sequencing for a consanguineous family with a recessive inheritance pattern of female infertility characterized by oocytes with a thin zona pellucida (ZP) and fertilization failure in routine in vitro fertilization. Subsequent PV screening of ZP2 was performed in additional eight unrelated infertile women whose oocytes exhibited abnormal ZP and similar fertilization failure. Expression of ZP proteins was assessed in mutant oocytes by immunostaining, and functional studies of the wild-type and mutant proteins were carried out in CHO-K1 cells.

RESULTS

Two homozygous s PV (c.1695-2A>G, and c.1691_1694dup (p.C566Wfs*5), respectively) of ZP2 were identified in the affected women from two unrelated consanguineous families. All oocytes carrying PV were surrounded by a thin ZP that was defective for sperm-binding. Immunostaining indicated a lack of ZP2 protein in the thin ZP. Studies in CHO cells showed that both PV resulted in a truncated ZP2 protein, which might be intracellularly sequestered and prematurely interacted with other ZP proteins.

CONCLUSION

We identified loss-of-function PV of ZP2 causing a structurally abnormal and dysfunctional ZP, resulting in fertilization failure and female infertility.

[Analysis of FOXL2 gene mutations in 5 families affected with blepharophimosis, ptosis and epicanthus inversus syndrome]

OBJECTIVE

To screen for FOXL2 gene mutations in 6 patients with blepharophimosis, ptosis, and epicanthus inversus syndrome (BPES), and explore their genotype-phenotype correlation.

METHODS

Peripheral venous blood samples were collected from the patients for the extraction of genomic DNA. PCR and Sanger sequencing were employed to analyze the coding region and flanking sequences of the FOXL2 gene. Pathogenicity of the identified mutations was verified through literature review and bioinformatic analysis.

RESULTS

A heterozygous c.672_701dup30 mutation was found in the probands from the two familial cases, while three heterozygous mutations (two were novel), namely c.462_468del (p.Pro156Argfs*113), c.251T to A (p.Ile84Asn) and c.988_989insG (p.Ala330Glyfs*204) were detected in the three sporadic cases. Literature review and bioinformatic analysis indicated that all these mutations are pathogenic.

CONCLUSION

Identification of causative mutations in the BPES patients has provided a basis for genetic counseling and reproductive guidance. The novel mutations have enriched the mutation spectrum of the FOXL2 gene.

[Karyotyping and analysis of 5α -reductase-2 gene mutation in 25 patients with hypospadias]

OBJECTIVE

To analyze the karyotypes and SRD5A2 gene mutations in 25 patients with sporadic or familial hypospadias.

METHODS

The patients included 10 adults and 15 children, whose chromosomes were analyzed by G-banded karyotyping, and the SRD5A2 genes were sequenced.

RESULTS

Two patients were found to have an abnormal karyotype, while eight have carried compound heterozygous mutations of the SRD5A2 gene, which included 5 genotypes formed by 6 types of mutations, i.e., p.G203S/p.R227Q, p.R227Q/p.R246Q, p.Q6X/p.Q71X, p.L20P/p.G203S, and p.Q71X/p.R227Q. Mutations of the SRD5A2 gene were present in 32% (8/25) of all patients, 35% (8/23) in those with a normal karyotype, and 44.4% (8/18) in those with proximal type hypospadia. Bioinformatic analysis, literature review and pedigree analysis confirmed that all such mutations are pathogenic.

CONCLUSION

Chromosomal anomalies and mutations of the SRD5A2 gene are the main cause of hypospadias. Sequencing of the SRD5A2 gene may explain the etiology of nearly half of the patients with proximal type of hypospadas but a normal karyotype, which can facilitate genetic consulting.

[Study of two Chinese families affected with resistant ovarian syndrome resulted from novel mutations of FSHR gene]

OBJECTIVE

To explore the genetic etiology for two Chinese families affected with hypergonadotropic amenorrhea and normal number of antral follicles.

METHODS

Peripheral venous blood samples were collected from the families for the extraction of genomic DNA. Mutations of FSHR and LHCGR genes were screened using PCR and Sanger sequencing. Suspected pathogenic mutations were verified in other members of the families. Bioinformatics software and NCBI were used to analyze the pathogenicity of the mutations.

RESULTS

Two previously unreported homozygous mutations, c.419delA and c.1510C>T of the FSHR gene were found in the probands of family I and II, respectively. Pedigree and bioinformatics analysis suggested that both mutations were pathogenic. Literature review suggested that both families were affected with resistant ovary syndrome rather than premature ovarian failure.

CONCLUSION

Two novel mutations of the FSHR gene have been identified, which have enriched the spectrum of FSHR gene mutations and provided a basis for genetic counseling and direction for reproduction.

Reciprocal Translocation Carrier Diagnosis in Preimplantation Human Embryos

Preimplantation genetic diagnosis (PGD) is widely applied in reciprocal translocation carriers to increase the chance for a successful live birth. However, reciprocal translocation carrier embryos were seldom discriminated from the normal ones mainly due to the technique restriction. Here we established a clinical applicable approach to identify precise breakpoint of reciprocal translocation and to further distinguish normal embryos in PGD. In the preclinical phase, rearrangement breakpoints and adjacent single nucleotide polymorphisms (SNPs) were characterized by next-generation sequencing following microdissecting junction region (MicroSeq) from 8 reciprocal translocation carriers. Junction-spanning PCR and sequencing further discovered precise breakpoints. The precise breakpoints were identified in 7/8 patients and we revealed that translocations in 6 patients caused 9 gene disruptions. In the clinical phase of embryo analysis, informative SNPs were chosen for linkage analyses combined with PCR analysis of the breakpoints to identify the carrier embryos. From 15 blastocysts diagnosed to be chromosomal balanced, 13 blastocysts were identified to be carriers and 2 to be normal. Late prenatal diagnoses for five carriers and one normal fetus confirmed the carrier diagnosis results. Our results suggest that MicroSeq can accurately evaluate the genetic risk of translocation carriers and carrier screen is possible in later PGD treatment.

Correlation analysis between ultrasound findings and abnormal karyotypes in the embryos from early pregnancy loss after in vitro fertilization-embryo transfer

PURPOSE

The purpose of the study is to evaluate the correlation between ultrasound findings and abnormal karyotypes in early pregnancy losses (EPLs) after in vitro fertilization-embryo transfer (IVF-ET).

METHODS

This retrospective analysis assessed 2172 cases of EPL after IVF-ET occurring between January 2008 and December 2013. The cases were examined via transvaginal ultrasonography (TVS). Embryonic tissue karyotyping following miscarriage was performed using a comparative genomic hybridization (CGH) analysis with fluorescence in situ hybridization (FISH). The correlations between the ultrasound findings and the karyotypes were evaluated.

RESULTS

Six categories of ultrasound findings were observed: normal ultrasound, empty sac, yolk sac only, small gestational sac, small embryonic pole, and early symmetrical arrested growth. The overall rate of abnormal karyotypes was 44.9 % (976/2172), and the rate of abnormal karyotypes associated with a normal ultrasound, empty sac, yolk sac only, small gestational sac, small embryonic pole, and early symmetrical arrested growth was 49.5 % (218/440), 28.1 % (138/491), 43.4 % (197/454), 50.0 % (43/86), 49.8 % (155/311), and 57.7 % (225/390), respectively. Compared with the other groups, the prevalence of chromosomal abnormalities was significantly higher in the early symmetrical arrested growth group but was markedly lower in the empty sac group in all cases and when cases of 46,XX were excluded (p < 0.05). Trisomy 16 was the most common chromosomal abnormality in the yolk sac only, small embryonic pole and early symmetrical arrested growth groups. In the empty sac, small gestational sac and normal ultrasound groups, monosomy X was the most frequent abnormality.

CONCLUSIONS

Chromosomal anomalies may be associated with specific types of ultrasound findings in EPLs after IVF-ET.

Correlation between chromosomal distribution and embryonic findings on ultrasound in early pregnancy loss after IVF-embryo transfer

STUDY QUESTION

Do early pregnancy losses (EPLs) with and without embryos differ in chromosomal distributions?

SUMMARY ANSWER

The chromosomal abnormality rate is significantly higher in miscarriages with embryos than without after in vitro fertilization (IVF)-embryo transfer.

WHAT IS KNOWN ALREADY

Chromosomal abnormalities are the main causes of EPLs, the rate of which is up to 24-30% in the IVF population. Little research has been conducted on the correlations between the chromosomal distributions of EPL and the existence of an embryo or with the postmortem embryonic pole length, and the existing results have been inconsistent.

STUDY DESIGN, SIZE, DURATION

The data of 2172 women who underwent dilation and curettage (D&C) from January 2008 to December 2013 for missed abortion were analyzed retrospectively. The existence of an embryonic pole and the length of the postmortem embryonic pole of the EPL were evaluated by transvaginal sonography (TVS). Ultrasound findings were compared with karyotype results.

PARTICIPANTS/MATERIALS, SETTING, METHOD

This analysis included 2172 infertility patients who had singleton pregnancies and experienced EPLs after IVF-embryo transfer. The EPLs were divided into embryonic and anembryonic groups based on TVS diagnosis. The crown-rump length of the fetal pole (observed once) was measured twice for each fetus after confirmation of fetal death, subject to the final measurement before D&C. The karyotype analysis was performed using comparative genomic hybridization (CGH) plus fluorescence in situ hybridization technology.

MAIN RESULTS AND THE ROLE OF CHANCE

The chromosomal abnormality rate was significantly higher in male miscarriages with an embryo than in those without an embryo (54.14% versus 37.50%, P ≤ 0.001). In the anembryonic group, the abnormal karyotype rate was significantly higher in the yolk sac only than that in the empty sac group (46.11% versus 29.77%, P = 0.001); in the embryonic group, the abnormal karyotype rate in miscarriages with postmortem embryonic pole length >20 mm was significantly lower than that in miscarriages with pole length <10 mm (P = 0.006) and 10-20 mm (P = 0.036). There were significant differences in abnormal karyotype rates among miscarriages of different developmental stages (P ≤ 0.001). The cases with embryonic stages had the highest risk (54.89%) of an abnormal karyotype and those with fetal stages had the lowest risk (18.18%). There were significant differences in the length of postmortem embryonic poles among groups with different karyotypes (P ≤ 0.001). In addition, trisomy 21, monosomy X and triploidy had the longest lengths of postmortem embryonic poles (16, 15.3 and 11.6 mm, respectively).

LIMITATIONS, REASONS FOR CAUTION

Although the efficacy of a non-parametric test is less than that of a parametric test, non-parametric testing was used to compare the embryonic pole lengths in this study, owing to the non-normal distribution and non-homogeneous variances caused by limited cases of some rare chromosomal abnormalities. Another limitation was that CGH was unable to detect mosaicism. Furthermore, the results were not compared with a non-IVF population. Finally, maternal cell contamination is a major problem in studying miscarriage tissue, even using molecular techniques.

WIDER IMPLICATIONS OF THE FINDINGS

Although TVS findings clearly cannot replace karyotype information, our results are important because they call attention to the fact that EPLs that occur after implantation but prior to embryo formation frequently have normal karyotypes. This finding might direct future research towards studies of DNA sequences, or of epigenetic correlations with pregnancy failure.

STUDY FUNDING/COMPETING INTERESTS

This study was funded by the Scientific Research Foundation of Reproductive and Genetic Hospital of Citic-Xiangya. The authors have declared that no conflicts of interest exist.

TRIAL REGISTRATION NUMBER

N/A.

[Genetic analysis for 2 females carrying idic(Y)(p) and with sex development disorders]

OBJECTIVE

To investigate the phenotype-genotype association of isodicentromere Y chromosome by analysis of two female patients carrying the chromosome with sexual development disorders.

METHODS

The karyotypes of the two patients were determined by application of conventional G banding of peripheral blood samples and fluorescence in situ hybridization (FISH). PCR was applied to detect the presence of SRY gene.

RESULTS

Conventional karyotype analysis showed case 1 to be a mosaic: mos.45,X[38]/46,X,+mar[151]/47,XY,+mar[5]/47,X,+mar × 2[2]/46,XY[4], FISH showed that 12 different cell lines were presented in the karyotype of case 1 and partial cell lines with SRY gene, the marker is an isodicentromere Y chromosome [idic(Y)(p)]. No mutation was found in the SRY gene. The karyotype of case 2 was mos.45,X[25]/46,X,+mar[35]. FISH showed the marker to be an idic(Y)(p) without the SRY gene.

CONCLUSION

The karyotype of patients carrying idic(Y)(p) seems unstable, and female patients have the characteristics of short stature and secondary sexual hypoplasia. Karyotype analysis combined with FISH analysis can accurately determine the breakpoint of idic(Y) and identify the types of complex mosaic, which may facilitate genetic counseling and prognosis.

Obstetric and neonatal outcomes in blastocyst-stage biopsy with frozen embryo transfer and cleavage-stage biopsy with fresh embryo transfer after preimplantation genetic diagnosis/screening

OBJECTIVE

To study whether embryo biopsy for preimplantation genetic diagnosis/preimplantation genetic screening (PGD/PGS) can influence pregnancy complications and neonatal outcomes.

DESIGN

Retrospective analysis.

SETTING

University-affiliated center.

PATIENT(S)

This study included data from women and their neonates born after PGD/PGS (n = 317).

MAIN OUTCOME MEASURE(S)

Questionnaires were designed to obtain information relating to pregnancy complications and neonatal outcomes.

INTERVENTION(S)

Two major strategies for PGD/PGS were evaluated. Blastocyst-stage biopsy and frozen embryo transfer (BB-FET) was carried out in 166 patients, and cleavage-stage biopsy and fresh embryo transfer (CB-ET) was carried out in 129 patients.

RESULT(S)

The incidence of gestational hypertension was significantly higher in BB-FET compared with in CB-ET (9.0% vs. 2.3%, adjusted odds ratio [OR] and 95% confidence interval [CI], 4.85 [1.34, 17.56]). In twins, the birthweight (median [range], 2.70 kg [1.55-3.60 kg] vs. 2.50 kg [1.23-3.75 kg]) was higher in BB-FET than in CB-ET and the gestational age was longer in BB-FET than in CB-ET (median [range], 36.71 weeks [31.14-39.29 weeks] vs. 35.57 weeks [30.57-38.43 weeks]). There was no difference in the incidence of singleton births between the two groups except in the incidence of preterm births (28-37 weeks; 5.3% vs. 16.5% in CB-ET and BB-FET). No significant differences were detected in the incidence of perinatal deaths, birth defects, gender of neonates, and large for gestational age in both singletons and twins, although the numbers of some events were small.

CONCLUSION(S)

BB-FET is associated with a higher incidence of gestational hypertension but better neonatal outcomes compared with CB-ET, especially in twins.

Number of biopsied trophectoderm cells is likely to affect the implantation potential of blastocysts with poor trophectoderm quality

OBJECTIVE

To evaluate whether the developmental potential of the blastocyst is affected by the number of trophectoderm (TE) cells biopsied in preimplantation genetic diagnosis (PGD) cycles.

DESIGN

Retrospective study.

SETTING

University-affiliated center.

PATIENT(S)

Women underwent PGD cycles of blastocyst biopsy and fluorescence in situ hybridization analysis.

INTERVENTION(S)

Not applicable.

MAIN OUTCOME MEASURE(S)

Biopsied TE cell number of blastocysts, survival, and implantation rates.

RESULT(S)

The biopsied TE cell number was affected by the TE quality and experience of different embryologists. The diagnostic efficiency increased when from one to five cells were biopsied (86.7%, 91.7%%, 96.0%, 96.8%, to 98.7%) and was maximized when more than six cells were biopsied. To compare the clinical efficiencies, blastocysts were divided into four groups according to biopsied TE cell number: 1-5, 6-10, 11-15, and 16-41. For the blastocysts with grade A TE score, no significant difference was observed in the survival and implantation rates among the four groups. For the blastocysts with grades B and C TE scores, the survival rates showed no significant differences among the four groups, but a significant decreasing trend in implantation rates was observed with increasing biopsied TE cell number.

CONCLUSION(S)

The implantation potential is negatively affected by the biopsied TE cell number in blastocysts with poor TE morphological score.

Effect of temperature on endogenous hormone levels and opposite phyllotaxy in maize leaf primordial

Newly identified maize (Zea mays) mutants with opposite leaf phyllotaxy are important in the study of the maize crop. Previous studies have revealed the developmental mechanism of opposite phyllotaxy on the physiological, cellular, and molecular levels. However, there have been few reports regarding the effects of changes in endogenous hormone levels in maize leaf primordia under different conditions. We conducted field studies to examine the influence of different environmental factors on leaf primordia differentiation. Our results indicated that compared with other major environmental factors, temperature was significantly positively correlated with the ratio of maize plants with opposite phyllotaxy. We examined endogenous hormone levels in maize at different temperatures using an enzyme-linked immunosorbent assay. The results showed that the ratio of maize plants with opposite phyllotaxy was mainly influenced by the cytokinin/auxin ratio. In addition, at the same temperature, the ratio of cytokinin/auxin in maize with opposite phyllotaxy was significantly higher than that near isogenic lines with alternate phyllotaxy.

[Abnormal expression of PEX10 gene may be related to epilepsy associated with 1p36 copy number variations]

OBJECTIVE

To assess the association of PEX10 gene and 1p36 copy number variations in 1p36 region with concurrent epilepsy through analyzing 3 cases.

METHODS

The karyotypes of 3 patients were determined by high resolution chromosome banding, multiplex ligation dependent probe amplification (MLPA), fluorescence in situ hybridization (FISH) combined with single nucleotide polymorphism array (SNP) technology. Real-time PCR was carried out to determine the mRNA levels of PEX10 gene in peripheral blood of the patients.

RESULTS

No abnormality was found upon high resolution karyotyping. MLPA analysis showed that all of the 3 patients had a copy number variation of subtelomeric region in the short arm of chromosome 1, which was confirmed by FISH and SNP chip analyses. Case 1 and case 2 both had an epilepsy phenotype, and their copy number variations have encompassed the PEX10 gene. On the other hand, case 3 has absent epilepsy, and its PEX10 gene copy number was normal. Family investigation confirmed that the chromosome abnormalities in all of the 3 cases were of de novo type. Compared with healthy controls, real-time PCR showed that mRNA of the PEX10 gene was increased in case 1 but decreased in case 2.

CONCLUSION

The abnormal expression of PEX10 gene resulting from copy number variations of 1p36 region may be associated with the epilepsy phenotype.

Differentiation of primordial germ cells from induced pluripotent stem cells of primary ovarian insufficiency

STUDY QUESTION

Can the induced pluripotent stem cells (iPSCs) derived from women with primary ovarian insufficiency (POI) differentiate into germ cells for potential disease modeling in vitro?

SUMMARY ANSWER

The iPSC lines derived from POI patients with 46, X, del(X)(q26) or 46, X, del(X)(q26)9qh+ could differentiate into germ cells and expressed lower levels of genes in the deletion region of the X chromosome.

WHAT IS KNOWN ALREADY

iPSC technology has been envisioned as an approach for generating patient-specific stem cells for disease modeling and for developing novel therapies. It has also been confirmed that iPSCs differentiate into germ cells.

STUDY DESIGN, SIZE, DURATION

We compared the differentiation ability of germ cells and the gene expression level of germ cell-related genes in the X chromosome deletion region of iPSC lines derived from POI patients (n = 2) with an iPSC line derived from normal fibroblasts (n = 1).

PARTICIPANTS/MATERIALS, SETTING, METHODS

We established three iPSC lines from two patients with partial Xq deletion-induced POI and normal fibroblasts by overexpressing four factors: octamer-binding transcription factor 4 (OCT4), sex-determining region Y-box 2 (SOX2), Nanog homeobox (NANOG), and lin-28 homolog (LIN28), using lentiviral vectors. We then generated stable-transfected fluorescent reporter cell lines under the control of the Asp-Glu-Ala-Asp box polypeptide 4 (DDX4, also called VASA) promoter, and selected clonal derived sublines. We induced subline differentiation into germ cells by adding Wnt3a (30 ng/ml) and bone morphogenetic protein 4 (100 ng/ml). After 12 days of differentiation, green fluorescent protein (GFP)-positive and GFP-negative cells were isolated via fluorescence-activated cell sorting and analyzed for endogenous VASA protein (immunostaining) and for germ cell markers and genes expressed in the deleted region of the X chromosome (quantitative RT-PCR).

MAIN RESULTS AND THE ROLE OF CHANCE

The POI- and normal fibroblast-derived iPSCs had typical self-renewal and pluripotency characteristics. After stable transfection with the VASA-GFP construct, the sublines POI1-iPS-V.1, POI2-iPS-V.1 and hEF-iPS-V.1 produced green fluorescent cells in the differentiated cultures, and the percentage of GFP-positive cells increased over the 12 days of differentiation to a maximum of 6.9 ± 0.33%, 5.3 ± 0.57% and 8.5 ± 0.29%, respectively, of the total cell population. Immunohistochemical analysis confirmed that endogenous VASA was enriched in the GFP-positive cells. Quantitative reverse transcription-PCR revealed significantly higher expression of germ cell markers [PR domain containing 1, with ZNF domain (PRDM1, BLIMP1), developmental pluripotency-associated 3 (DPPA3, STELLA), deleted in azoospermia-like (DAZL), and VASA (DDX4)] in GFP-positive cells than in GFP-negative cells. Moreover, the GFP-positive cells from POI-iPSCs had reduced expression of the family with sequence similarity 122C (FAM122C), inhibitor of kappa light polypeptide gene enhancer in B-cells, kinase gamma (IKBKG), and RNA binding motif protein, X-linked (RBMX), genes located in the deleted region of the X chromosome and that are highly expressed in differentiated germ cells, compared with cells from normal iPSCs.

LIMITATIONS, REASONS FOR CAUTION

Gene expression profiling indicated that the germ cells differentiated from POI-iPSCs were pre-meiotic. Therefore, how the differentiated primordial germ cells could progress further to meiosis and form follicles remains to be determined in the study of POI.

WIDER IMPLICATIONS OF THE FINDINGS

Our results might provide an in vitro model for studying germ cell development in patients with POI.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by grants from the Major State Basic Research Development Program of China (No. 2012CB944901), the National Science Foundation of China (No. 81222007 and 81471432), the Program for New Century Excellent Talents in University and the Fundamental Research Funds for Central Universities (No. 721500003). The authors have no competing interests to declare.

TRIAL REGISTRATION NUMBER

Not applicable.

Clinical outcome of preimplantation genetic diagnosis and screening using next generation sequencing

Background

Next generation sequencing (NGS) is now being used for detecting chromosomal abnormalities in blastocyst trophectoderm (TE) cells from in vitro fertilized embryos. However, few data are available regarding the clinical outcome, which provides vital reference for further application of the methodology. Here, we present a clinical evaluation of NGS-based preimplantation genetic diagnosis/screening (PGD/PGS) compared with single nucleotide polymorphism (SNP) array-based PGD/PGS as a control.

Results

A total of 395 couples participated. They were carriers of either translocation or inversion mutations, or were patients with recurrent miscarriage and/or advanced maternal age. A total of 1,512 blastocysts were biopsied on D5 after fertilization, with 1,058 blastocysts set aside for SNP array testing and 454 blastocysts for NGS testing. In the NGS cycles group, the implantation, clinical pregnancy and miscarriage rates were 52.6% (60/114), 61.3% (49/80) and 14.3% (7/49), respectively. In the SNP array cycles group, the implantation, clinical pregnancy and miscarriage rates were 47.6% (139/292), 56.7% (115/203) and 14.8% (17/115), respectively. The outcome measures of both the NGS and SNP array cycles were the same with insignificant differences. There were 150 blastocysts that underwent both NGS and SNP array analysis, of which seven blastocysts were found with inconsistent signals. All other signals obtained from NGS analysis were confirmed to be accurate by validation with qPCR. The relative copy number of mitochondrial DNA (mtDNA) for each blastocyst that underwent NGS testing was evaluated, and a significant difference was found between the copy number of mtDNA for the euploid and the chromosomally abnormal blastocysts. So far, out of 42 ongoing pregnancies, 24 babies were born in NGS cycles; all of these babies are healthy and free of any developmental problems.

Conclusions

This study provides the first evaluation of the clinical outcomes of NGS-based pre-implantation genetic diagnosis/screening, and shows the reliability of this method in a clinical and array-based laboratory setting. NGS provides an accurate approach to detect embryonic imbalanced segmental rearrangements, to avoid the potential risks of false signals from SNP array in this study.

Electronic supplementary material

The online version of this article (doi:10.1186/2047-217X-3-30) contains supplementary material, which is available to authorized users.

Blastocysts can be rebiopsied for preimplantation genetic diagnosis and screening

OBJECTIVE

To evaluate the clinical value of re-examining the test-failure blastocysts in preimplantation genetic diagnosis/screening cycles.

DESIGN

Retrospective study.

SETTING

University-affiliated center.

PATIENT(S)

Women with test-failure blastocysts cryopreserved in preimplantation genetic diagnosis/screening cycles.

INTERVENTION(S)

Cryopreserved test-failure blastocysts were warmed and underwent a second round of biopsy, single nucleotide polymorphism microarray analysis, and vitrification, and the normal blastocysts were warmed again for ET.

MAIN OUTCOME MEASURE(S)

The percentage of test-failure blastocysts for transfer, the implantation rate per transferred blastocyst, and the live birth rate.

RESULT(S)

A total of 106 test-failure blastocysts from 77 cycles were warmed for re-examination. A total of 73 blastocysts that completely expanded were considered to have survived the warming process and were successfully rebiopsied. After single nucleotide polymorphism array analysis, 70 blastocysts yielded whole genome amplification product, and 31 had normal chromosomes (44.3%). A total of 19 normal blastocysts were warmed for ET, of which 18 survived and were transferred. The clinical pregnancy rate (implantation rate) was 50.0% in 10 single blastocyst transfer cycles, and all the implanted blastocysts resulted in healthy live births.

CONCLUSION(S)

Test-failure blastocysts that survived from the first warming procedure can tolerate a second round of biopsy, vitrification, and warming, have a high chance of having normal chromosomes, and are worth being re-examined.

Physiological oxygen prevents frequent silencing of the DLK1-DIO3 cluster during human embryonic stem cells culture

Genetic and epigenetic alterations are observed in long-term culture (>30 passages) of human embryonic stem cells (hESCs); however, little information is available in early cultures. Through a large-scale gene expression analysis between initial-passage hESCs (ihESCs, <10 passages) and early-passage hESCs (ehESCs, 20-30 passages) of 12 hESC lines, we found that the DLK1-DIO3 gene cluster was normally expressed and showed normal methylation pattern in ihESC, but was frequently silenced after 20 passages. Both the DLK1-DIO3 active status in ihESCs and the inactive status in ehESCs were inheritable during differentiation. Silencing of the DLK1-DIO3 cluster did not seem to compromise the multilineage differentiation ability of hESCs, but was associated with reduced DNA damage-induced apoptosis in ehESCs and their differentiated hepatocyte-like cell derivatives, possibly through attenuation of the expression and phosphorylation of p53. Furthermore, we demonstrated that 5% oxygen, instead of the commonly used 20% oxygen, is required for preserving the expression of the DLK1-DIO3 cluster. Overall, the data suggest that active expression of the DLK1-DIO3 cluster represents a new biomarker for epigenetic stability of hESCs and indicates the importance of using a proper physiological oxygen level during the derivation and culture of hESCs.

Using SNP array to identify aneuploidy and segmental imbalance in translocation carriers

Translocation is one of the more common structural rearrangements of chromosomes, with a prevalence of 0.2%. The two most common types of chromosomal translocations, Robertsonian and reciprocal, usually result in no obvious phenotypic abnormalities when balanced. However, these are still associated with reproductive risks, such as infertility, spontaneous abortion and the delivery of babies with mental retardation or developmental delay.

In recent years, array-based whole-genome amplification (WGA) technologies, including microarray comparative genomic hybridization (array CGH; aCGH) and single-nucleotide polymorphism (SNP) micro-arrays, have enabled the screening of every chromosome for whole-chromosome aneuploidy and segmental imbalance. These techniques have been shown to have clinical application for translocation carriers. Promising studies have indicated that array-based PGD of translocation carriers can lead to transfer pregnancy rates of 45–70% [2].

In addition to genetic testing techniques, the embryo biopsy stage (polar body, cleavage embryo or blastocyst) and the mode of embryo transfer (fresh or frozen embryos) can affect the outcome of PGD. It is now generally recommended that blastomere biopsy should be replaced by blastocyst biopsy to avoid a high mosaic rate and biopsy-related damage to cleavage-stage embryos, which might affect embryo development. However, more clinical data are required to confirm that the technique of SNP array-based PGD (SNP-PGD) combined with trophectoderm (TE) biopsy and frozen embryo transfer (FET) is superior to traditional FISH-PGD combined with Day 3 (D3) blastomere biopsy and fresh embryo transfer.

[Analysis of a novel mutation of AR gene in a patient featuring mild androgen insensitivity syndrome]

OBJECTIVE

To investigate the clinical and molecular genetics characteristics of a patient with mild androgen insensitivity syndrome (MAIS).

METHODS

Clinical data of the patient was collected, and DNA was isolated from peripheral blood sample. Eight exons of AR gene were amplified by PCR with specific primers and directly sequenced by Sanger method. The results were compared with standard sequences from GenBank. Online Polyphen-2 software was applied to predict the effect of mutation on the protein function and compare the conservation of the sequence at the mutation site in various species. The exon of the AR gene containing the mutated site was analyzed in 90 unrelated normal males using PCR and restrictive digestion with Sfa NI.

RESULTS

Sequence analysis has detected a novel missense mutation in codon 176 of exon 1 (Ser176Arg) of the AR gene. Analysis with polyphen-2 software has indicated the codon to be highly conserved across various species, and that the S176A mutation has caused damage to the protein structure and function (prediction score=0.999). The same mutation was not detected in 90 healthy males.

CONCLUSION

The S176A mutation of the AR gene may contribute to the mild androgen insensitivity syndrome.