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The genetic causes of oocyte meiotic deficiency (OMD), a form of primary infertility characterised by the production of immature oocytes, remain largely unexplored. Using whole exome sequencing, we found that 26% of a cohort of 23 subjects with OMD harboured the same homozygous nonsense pathogenic mutation in PATL2 , a gene encoding a putative RNA‐binding protein. Using Patl2 knockout mice, we confirmed that PATL2 deficiency disturbs oocyte maturation, since oocytes and zygotes exhibit morphological and developmental defects, respectively. PATL2's amphibian orthologue is involved in the regulation of oocyte mRNA as a partner of CPEB. However, Patl2's expression profile throughout oocyte development in mice, alongside colocalisation experiments with Cpeb1, Msy2 and Ddx6 (three oocyte RNA regulators) suggest an original role for Patl2 in mammals. Accordingly, transcriptomic analysis of oocytes from WT and Patl2 −/− animals demonstrated that in the absence of Patl2, expression levels of a select number of highly relevant genes involved in oocyte maturation and early embryonic development are deregulated. In conclusion, PATL2 is a novel actor of mammalian oocyte maturation whose invalidation causes OMD in humans. Synopsis A novel mutation in the gene PATL2 causes oocyte maturation arrest at the germinal vesicle (GV) stage. In mice, Patl2 deficiency during oocyte growth modifies the global transcriptional landscape of GV oocytes, causing dramatic defects and hampering normal maturation. In a cohort of 23 infertile women from North Africa with oocyte meiotic deficiency (OMD), a truncating mutation in the gene PATL2 , encoding an RNA‐binding protein, was identified in 26% of patients. Patl2 knockout female mice presented severe subfertility, confirming the human diagnostic. Patl2 knockout mouse oocytes could progress to the MII stage, however with numerous morphological defects hampering normal fertilisation and development. Patl2 is not detectable in primordial follicle oocytes, but is strongly expressed during oocyte growth and remains detectable at least until the MII stage. Patl2 has a unique expression pattern from primordial follicle‐stage to MII‐stage oocytes and did not colocalise with Cpeb1, Msy2 or Ddx6 known to stabilise mRNA during oocyte growth. Patl2 deficiency leads to a down or up‐regulation of a subset of mRNAs encoding proteins which are crucial for oocyte meiotic progression and early embryonic development, with no effect on the GV‐MII transition. Graphical Abstract A novel mutation in the gene PATL2 causes oocyte maturation arrest at the germinal vesicle (GV) stage. In mice, Patl2 deficiency during oocyte growth modifies the global transcriptional landscape of GV oocytes, causing dramatic defects and hampering normal maturation.

Background Men with non-obstructive azoospermia (NOA) may have sperm in their testes and a procedure of sperm retrieval and assisted reproduction is required in them to allow fertility. Standard procedures such as fine needle aspiration (FNA) and conventional testicular sperm extraction (cTESE) harvest random samples with a sperm retrieval rate (SRR) of 45%. Microdissection testicular sperm extraction (mTESE) is nowadays considered to be the most accurate technique to retrieve sperm in men with NOA. This procedure can identify dilated tubules that are more likely to contain viable sperm with a SRR of 60%. Results In our center, testicular biopsy was conducted in a standard fashion in 321 patients with NOA until March 2003. From then to December 2017, due to the lack of an operating microscope, we used 6 fold magnifying loupes to perform a step-by-step macro- mTESE in 1050 patients. Sperm was found in the first testis in 61% of the cases, leading to stop the procedure with less testicular damage. We increased our SRR from 43 to 51.8% in an acceptable operating time of 75mn for both sides. Conclusions In institutions where surgeons cannot afford an operating microscope, this modified mTESE technique using × 6 magnifying loupes is reliable, especially in patients with low testicular volumes and high FSH, in whom dilated tubules can be easily identified from the surrounding tissue.

The genetic causes of oocyte meiotic deficiency (OMD), a form of primary infertility characterised by the production of immature oocytes, remain largely unexplored. Using whole exome sequencing, we found that 26% of a cohort of 23 subjects with OMD harboured the same homozygous nonsense pathogenic mutation in PATL2, a gene encoding a putative RNA‐binding protein. Using Patl2 knockout mice, we confirmed that PATL2 deficiency disturbs oocyte maturation, since oocytes and zygotes exhibit morphological and developmental defects, respectively. PATL2's amphibian orthologue is involved in the regulation of oocyte mRNA as a partner of CPEB. However, Patl2's expression profile throughout oocyte development in mice, alongside colocalisation experiments with Cpeb1, Msy2 and Ddx6 (three oocyte RNA regulators) suggest an original role for Patl2 in mammals. Accordingly, transcriptomic analysis of oocytes from WT and Patl2−/− animals demonstrated that in the absence of Patl2, expression levels of a select number of highly relevant genes involved in oocyte maturation and early embryonic development are deregulated. In conclusion, PATL2 is a novel actor of mammalian oocyte maturation whose invalidation causes OMD in humans.

Résumé Contexte Les patients ayant une azoospermie non obstructive confirmée peuvent néanmoins présenter des spermatozoïdes intratesticulaires nécessitant un prélèvement chirurgical en vue d’une injection intra cytoplasmique d’un spermatozoïde (ICSI). L’aspiration à l’aiguille ainsi que la biopsie classique à ciel ouvert ne permettent qu’un prélèvement aléatoire à l’aveugle assorti d’un taux de positivité de 45%. La biopsie avec microdissection sous microscope est. désormais considérée comme le « gold standard » et permet d’identifier les foyers de tubes séminifères dilatés qui sont le plus à même de contenir des spermatozoïdes mobiles. Résultats Dans notre centre d’Assistance Médicale à la Procréation (AMP), jusqu’en février 2003, le recueil de spermatozoïdes pour ICSI a été réalisé par une biopsie classique chez 321 patients avec une positivité de 43%. De mars 2003 à décembre 2017, du fait de l’absence de microscope opératoire, nous avons adapté le prélèvement microchirurgical à des loupes de fort grossissement (× 6) et pratiqué cette technique simplifiée chez 1050 patients. Les fragments sont examinés en extemporané par les embryologistes et chez 61% des patients, la positivité de la biopsie dans le premier testicule prélevé permet de sursoir à l’exploration du côté controlatéral, évitant ainsi une dissection inutile et potentiellement délétère. Grâce à cette modification, nous sommes passés de 43% à 51,8% de positivité avec un temps opératoire moyen de 75mn pour les 2 côtés. Conclusion Dans les centres d’AMP où l’on ne dispose pas de microscope opératoire ou lorsque le programme ne permet pas d’allouer une longue durée opératoire à la biopsie testiculaire sans compromettre le reste de l’activité chirurgicale, l’utilisation de loupes à fort grossissement (× 6) permet l’amélioration des résultats de la biopsie, particulièrement chez les patients présentant un petit volume testiculaire et une FSH élevée.