Until now, complete ex vivo spermatogenesis has been reported only in the mouse. In this species, the duration of spermatogenesis is 35 days, whereas it is 54 days in the rat and 74 days in humans. ...We performed long-term (until 60 days) cultures of fresh or frozen rat or human seminiferous tubule segments in a bioreactor made of a hollow cylinder of chitosan hydrogel. Testicular tissues were obtained from 8- or 20-day-old male rats or from adult human subjects who had undergone hormone treatments leading to a nearly complete regression of their spermatogenesis before bilateral orchiectomy for gender reassignment. The progression of spermatogenesis was assessed by cytological analyses of the cultures; it was related to a dramatic increase in the levels of the mRNAs specifically expressed by round spermatids, Transition protein 1, Transition protein 2, and Protamine 3 in rat cultures. From 2% to 3.8% of cells were found to be haploid cells by fluorescence in situ hybridization analysis of human cultures. In this bioreactor, long-term cultures of seminiferous tubule segments from prepubertal rats or from adult men allowed completion of the spermatogenic process leading to morphologically mature spermatozoa. Further studies will need to address the way of optimizing the yield of every step of spermatogenesis by adjusting the composition of the culture medium, the geometry, and the material properties of the chitosan hydrogel bioreactors. Another essential requirement is to assess the quality of the gametes produced ex vivo by showing their ability to produce normal offspring (rat) or their biochemical normality (human).
Xq28 int22h‐1/int22h‐2 duplication is the result of non‐allelic homologous recombination between int22h‐1/int22h‐2 repeats separated by 0.5 Mb. It is responsible for a syndromic form of intellectual ...disability (ID), with recurrent infections and atopic diseases. Minor defects, nonspecific facial dysmorphic features, and overweight have also been described. Half of female carriers have been reported with ID, whereas all reported evaluated born males present mild to moderate ID, suggesting complete penetrance. We collected data on 15 families from eight university hospitals. Among them, 40 patients, 21 females (one fetus), and 19 males (two fetuses), were carriers of typical or atypical Xq28 int22h‐1/int22h‐2 duplication. Twenty‐one individuals were considered asymptomatic (16 females and 5 males), without significantly higher rate of recurrent infections, atopia, overweight, or facial dysmorphism. Approximately 67% live‐born males and 23% live‐born female carriers of the typical duplication did not have obvious signs of intellectual disability, suggesting previously undescribed incomplete penetrance or low expression in certain carriers. The possibility of a second‐hit or modifying factors to this possible susceptibility locus is yet to be studied but a possible observational bias should be considered in assessing such challenging X‐chromosome copy number gains. Additional segregation studies should help to quantify this newly described incomplete penetrance.
After assembling a French cohort of 15 families with 40 carriers of the Xq28 int22h‐1/int22h‐2 duplication, we found that the penetrance of the associated syndromic intellectual disability was less than 100% in our male individuals and less than 50% in our female individuals, inconsistent with previous descriptions in the literature.
Introduction
Depending on the location of insertion of the gained region, F8 duplications can have variable clinical impacts from benign impact to severe haemophilia A phenotype.
Aim
To characterize ...two large Xq28 duplications involving F8 incidentally detected by chromosome microarray analysis (CMA) in two patients presenting severe intellectual disability but no history of bleeding disorder.
Methods
Whole genome sequencing (WGS) was performed in order to characterize the two large Xq28 duplications at nucleotide level.
Results
In patient 1, a 60–73 kb gained region encompassing the exons 23–26 of F8 and SMIM9 was inserted at the int22h‐2 locus following a non‐homologous recombination between int22h‐1 and int22h‐2. We hypothesized that two independent events, micro‐homology‐mediated break‐induced replication (MMBIR) and break‐induced replication (BIR), could be involved in this rearrangement. In patient 2, the CMA found duplication from 101 to 116‐kb long encompassing the exons 16–26 of F8 and SMIM9. The WGS analysis identified a more complex rearrangement with the presence of three genomic junctions. Due to the multiple micro‐homologies observed at breakpoints, a replication‐based mechanism such as fork stalling and template switching (FoSTeS) was greatly suspected. In both cases, these complex rearrangements preserved an intact copy of the F8.
Conclusion
This study highlights the value of WGS to characterize the genomic junction at the nucleotide level and ultimately better describe the molecular mechanisms involved in Xq28 structural variations. It also emphasizes the importance of specifying the structure of the genomic gain in order to improve genotype‐phenotype correlation and genetic counselling.
Objectives
Congenital heart defects (CHDs) may be isolated or associated with other malformations. The use of chromosome microarray (CMA) can increase the genetic diagnostic yield for CHDs by between ...4% and 10%. The objective of this study was to evaluate the value of CMA after the prenatal diagnosis of an isolated CHD.
Methods
In a retrospective, nationwide study performed in France, we collected data on all cases of isolated CHD that had been explored using CMAs in 2015.
Results
A total of 239 fetuses were included and 33 copy number variations (CNVs) were reported; 19 were considered to be pathogenic, six were variants of unknown significance, and eight were benign variants. The anomaly detection rate was 10.4% overall but ranged from 0% to 16.7% as a function of the isolated CHD in question. The known CNVs were 22q11.21 deletions (n = 10), 22q11.21 duplications (n = 2), 8p23 deletions (n = 2), an Alagille syndrome (n = 1), and a Kleefstra syndrome (n = 1).
Conclusion
The additional diagnostic yield was clinically significant (3.1%), even when anomalies in the 22q11.21 region were not taken into account. Hence, patients with a suspected isolated CHD and a normal karyotype must be screened for chromosome anomalies other than 22q11.21 duplications and deletions.
What's already known about this topic?
The use of a chromosome microarray can increase the genetic diagnostic yield for isolated congenital heart defects by between 4% and 10%.
What does this study add?
Broader use of chromosome microarrays is essential for the etiologic diagnosis of isolated congenital heart defects and will help to identify new candidate genes involved in cardiogenesis.
Chromoanagenesis is a cellular mechanism that leads to complex chromosomal rearrangements (CCR) during a single catastrophic event. It may result in loss and/or gain of genetic material and may be ...responsible for various phenotypes. These rearrangements are usually sporadic. However, some familial cases have been reported. Here, we studied six families in whom an asymptomatic or paucisymptomatic parent transmitted a CCR to its offspring in an unbalanced manner. The rearrangements were characterized by karyotyping, fluorescent in situ hybridization, chromosomal microarray (CMA) and/or whole genome sequencing (WGS) in the carrier parents and offspring. We then hypothesized meiosis‐pairing figures between normal and abnormal parental chromosomes that may have led to the formation of new unbalanced rearrangements through meiotic recombination. Our work indicates that chromoanagenesis might be associated with a normal phenotype and normal fertility, even in males, and that WGS may be the only way to identify these events when there is no imbalance. Subsequently, the CCR can be transmitted to the next generation in an unbalanced and unpredictable manner following meiotic recombination. Thereby, prenatal diagnosis using CMA should be proposed to these families to detect any pathogenic imbalances in the offspring.
We studied six families in whom an asymptomatic or paucisymptomatic mother or father transmitted a complex chromosomal rearrangement to its offspring in an unbalanced manner.
Karyotyping, fluorescent in situ hybridization, chromosomal microarray and/or whole genome sequencing (WGS) were performed to characterize the rearrangements and to hypothesize meiosis‐pairing figures that may have led to the formation of new unbalanced rearrangements through meiotic recombination.
ABSTRACT
Chromoanagenesis is the process by which a single catastrophic event creates complex rearrangements confined to a single or a few chromosomes. It is usually characterized by the presence of ...multiple deletions and/or duplications, as well as by copy neutral rearrangements. In contrast, an array CGH screen of patients with developmental anomalies revealed three patients in which a single chromosome carries from 8 to 11 large copy number gains confined to a single chromosome or chromosomal arm, but the absence of deletions. Subsequent fluorescence in situ hybiridization and massive parallel sequencing revealed the duplicons to be clustered together in distinct locations across the altered chromosomes. Breakpoint junction sequences showed both microhomology and non‐templated insertions of up to 40 bp. Hence, these patients each demonstrate a single altered chromosome of clustered insertional duplications, no deletions, and breakpoint junction sequences showing microhomology and/or non‐templated insertions. These observations are difficult to reconcile with current mechanistic descriptions of chromothripsis and chromoanasynthesis. Therefore, we hypothesize those rearrangements to be of a mechanistically different origin. In addition, we suggest that large untemplated insertional sequences observed at breakpoints are driven by a non‐canonical non‐homologous end joining mechanism.
Here we present three patients with developmental anomalies carrying a single chromosome with 8 to 11 large copy number gains, but no large deletions. FISH and DNA sequencing revealed these duplicons do not match the characteristics of typical previously reported chromothripsis‐like chromosomes, suggesting an alternative mechanistic origin.
Objective
We aimed to gather fetal cases carrying a 7q11.23 copy number variation (CNV) and collect precise clinical data to broaden knowledge of antenatal features in these syndromes.
Methods
We ...retrospectively recruited unrelated cases with 7q11.23 deletion, known as Williams‐Beuren syndrome (WBS), or 7q11.23 duplication who had prenatal ultrasound findings. We collected laboratory and clinical data, fetal ultrasound, cardiac ultrasound and fetal autopsy reports from 18 prenatal diagnostic centers throughout France.
Results
40 fetuses with WBS were collected and the most common features were intra‐uterine growth retardation (IUGR) (70.0%, 28/40), cardiovascular defects (30.0%, 12/40), polyhydramnios (17.5%, 7/40) and protruding tongue (15.0%, 6/40). Fetal autopsy reports were available for 11 cases and were compared with ultrasound prenatal features. Four cases of fetuses with 7q11.23 microduplication were collected and prenatal ultrasound signs were variable and often isolated.
Conclusion
This work strengthens the fact that 7q11.23 CNVs are associated with a broad spectrum of antenatal presentations. IUGR and cardiovascular defects were the most frequent ultrasound signs. By reporting the biggest series of antenatal WBS, we aim to better delineate distinctive signs in fetuses with 7q11.23 CNVs.
Key points
What is already known on this topic?
Deletion of the 7q11.23 region causes the Williams Beuren syndrome (WBS). The reciprocal duplication is responsible for a distinctive although less severe neurodevelopmental disorder.
Diagnosis of WBS is usually suspected postnatally in infants but its prenatal presentation remains challenging.
What does this study add?
Largest series of fetuses with a 7q11.23 deletion or a 7q11.23 duplication.
Antenatal ultrasound findings of prenatal 7q11.23 copy number variations.
Should testicular sperm extraction (TESE) in non-mosaic 47,XXY Klinefelter syndrome (KS) patients be performed soon after puberty or could it be delayed until adulthood?
The difference in sperm ...retrieval rate (SRR) in TESE was not significant between the 'Young' (15-22 years old) cohort and the 'Adult' (23-43 years old) cohort of non-mosaic KS patients recruited prospectively in parallel.
Several studies have tried to define predictive factors for TESE outcome in non-mosaic KS patients, with very heterogeneous results. Some authors have found that age was a pejorative factor and recommended performing TESE soon after puberty. To date, no predictive factors have been unanimously recognized to guide clinicians in deciding to perform TESE in azoospermic KS patients.
Two cohorts (Young: 15-22 years old; Adult: 23-43 years old) were included prospectively in parallel. A total of 157 non-mosaic 47,XXY KS patients were included between 2010 and 2020 in the reproductive medicine department of the University Hospital of Lyon, France. However 31 patients gave up before TESE, four had cryptozoospermia and three did not have a valid hormone assessment; these were excluded from this study.
Data for 119 patients (61 Young and 58 Adult) were analyzed. All of these patients had clinical, hormonal and seminal evaluation before conventional TESE (c-TESE).
The global SRR was 45.4%. SRRs were not significantly different between the two age groups: Young SRR=49.2%, Adult SRR = 41.4%; P = 0.393. Anti-Müllerian hormone (AMH) and inhibin B were significantly higher in the Young group (AMH: P = 0.001, Inhibin B: P < 0.001), and also higher in patients with a positive TESE than in those with a negative TESE (AMH: P = 0.001, Inhibin B: P = 0.036). The other factors did not differ between age groups or according to TESE outcome. AMH had a better predictive value than inhibin B. SRRs were significantly higher in the upper quartile of AMH plasma levels than in the lower quartile (or in cases with AMH plasma level below the quantification limit): 67.7% versus 28.9% in the whole population (P = 0.001), 60% versus 20% in the Young group (P = 0.025) and 71.4% versus 33.3% in the Adult group (P = 0.018).
c-TESE was performed in the whole study; we cannot rule out the possibility of different results if microsurgical TESE had been performed. Because of the limited sensitivity of inhibin B and AMH assays, a large number of patients had values lower than the quantification limits, preventing the definition a threshold below which negative TESE can be predicted.
In contrast to some studies, age did not appear as a pejorative factor when comparing patients 15-22 and 23-44 years of age. Improved accuracy of inhibin B and AMH assays in the future might still allow discrimination of patients with persistent foci of spermatogenesis and guide clinician decision-making and patient information.
The study was supported by a grant from the French Ministry of Health D50621 (Programme Hospitalier de Recherche Clinical Régional 2008). The authors have no conflicts of interest to disclose.
NCT01918280.
PDF
