The clinical value of optical genome mapping in the rapid characterization of RB1 duplication and 15q23q24.2 triplication, for more appropriate prenatal genetic counselling.

BACKGROUND: Despite recent advances in prenatal genetic diagnosis, medical geneticists still face considerable difficulty in interpreting the clinical outcome of copy-number-variant duplications and defining the mechanisms underlying the formation of certain chromosomal rearrangements. Optical genome mapping (OGM) is an emerging cytogenomic tool with proved ability to identify the full spectrum of cytogenetic aberrations. METHODS: Here, we report on the use of OGM in a prenatal diagnosis setting. Detailed breakpoint mapping was used to determine the relative orientations of triplicated and duplicated segments in two unrelated foetuses harbouring chromosomal aberrations: a de novo 15q23q24.2 triplication and a paternally inherited 13q14.2 duplication that overlapped partially with the RB1 gene. RESULTS: OGM enabled us to suggest a plausible mechanism for the triplication and confirmed that the RB1 duplication was direct oriented and in tandem. This enabled us to predict the pathogenic consequences, refine the prognosis and adapt the follow-up and familial screening appropriately. CONCLUSION: Along with an increase in diagnostic rates, OGM can rapidly highlight genotype-phenotype correlations, improve genetic counselling and significantly influence prenatal management.

Stratification of the risk of ovarian dysfunction by studying the complexity of intermediate and premutation alleles of the FMR1 gene.

FMR1 premutation female carriers are at risk of developing premature/primary ovarian insufficiency (POI) with an incomplete penetrance. In this study, we determined the CGG repeat size among 1095 women with diminished ovarian reserve (DOR) / POI and characterized the CGG/AGG substructure in 44 women carrying an abnormal FMR1 repeat expansion number, compared to a group of 25 pregnant women carrying an abnormal FMR1 CGG repeat size. Allelic complexity scores of the FMR1 gene were calculated and compared between the two groups. In the DOR/POI cohort, 2.1% of women presented with an intermediate repeat size and 1.9% with a premutation. Our results suggest that the risk of POI is highest in the mid-range of CGG repeats. We observed that the allelic score is significantly higher in POI women compared to the pregnant women group (p-value = 0.02). We suggest that a high allelic score due to more than 2 AGG interspersions in the context of an intermediate number of repetitions could favor POI. Larger studies are still needed to evaluate the relevance of this new tool for the determination of the individual risk of developing POI in women with abnormal number of CGG repeats.

Next Generation Sequencing Should Be Proposed to Every Woman With "Idiopathic" Primary Ovarian Insufficiency.

CONTEXT: Primary ovarian insufficiency (POI) affects 1% of women under 40 years of age. POI is idiopathic in more than 70% of cases. Though many candidate genes have been identified in recent years, the prevalence and pathogenicity of abnormalities are still difficult to establish. OBJECTIVE: Our primary objective was to evaluate the prevalence of gene variations in a large prospective multicentric POI cohort. Our secondary objective was to evaluate the correlation between phenotype and genotype. METHODS: Two hundred and sixty-nine well-phenotyped POI patients were screened for variants of 18 known POI genes (BMP15, DMC1, EIF2S2, FIGLA, FOXL2, FSHR, GDF9, GPR3, HFM1, LHX8, MSH5, NOBOX, NR5A1, PGRMC1, STAG3, XPNPEP2, BHLB, and FSHB) by next generation sequencing (NGS). Abnormalities were classified as "variant" or "variant of unknown signification" (VUS) according to available functional tests or algorithms (SIFT, Polyphen-2, MutationTaster). RESULTS: One hundred and two patients (38%) were identified as having at least 1 genetic abnormality. Sixty-seven patients (25%) presented at least 1 variant. Forty-eight patients presented at least 1 VUS (18%). Thirteen patients (5%) had combined abnormalities. NOBOX variants were the most common gene variants involved in POI (9%). Interestingly, we saw no significant differences in the previous family history of POI, ethnic origin, age at onset of POI, primary amenorrhea, or secondary menstrual disturbances between the different genotypes. CONCLUSION: In our study, a high percentage of patients presented gene variants detected by NGS analysis (38%). Every POI patient should undergo NGS analysis to improve medical cares of the patients.

Prenatal diagnosis of 2q13 duplications: The crucial role of the family survey in genetic counseling on novel copy number variations.

In recent years, the introduction of novel genome analysis technologies (such as array comparative genomic hybridization) has enabled the prenatal diagnosis of various recurrent copy number variations (CNVs). Some of these CNVs have been linked to a greater susceptibility of developmental and neuropsychiatric disorders; for example, recurrent duplication at the 2q13 locus is associated with developmental delay, dysmorphism and intellectual disability. However, this CNV has low penetrance and variable clinical expressivity. It also can be observed in healthy controls and can be transmitted by unaffected parents, making genetic counseling especially challenging. Here, we report on the inheritance of a 2q13 duplication in an asymptomatic family; the case highlights the role of the family survey in genetic counseling with regard to novel CNVs diagnosed before birth.

Are leptin and adiponectin involved in recurrent pregnancy loss?

AIM: The aim of this study was to investigate whether recurrent pregnancy loss (RPL) is associated with adipokine gene polymorphisms (namely the leptin -2548 (G/A), adiponectin 276 (G/T), and adiponectin 45 (T/G) polymorphisms) and/or adipokine serum levels. METHODS: A total of 145 women participated in the study. For the analysis of serum adipokine levels, 19 healthy fertile women (control group) and 60 women suffering from RPL were included. For the polymorphism analysis, 126 women suffering from RPL were included. Serum adipokine levels were determined using a commercial radioimmunoassay kit. Adipokine polymorphisms were analyzed using an allele-specific polymerase chain reaction (PCR). RESULTS: Our immunoassays revealed that serum leptin levels were similar in control and RPL groups (17.34 and 20.16 ng/mL, respectively). In contrast, serum adiponectin levels were significantly higher in women with RPL than in controls (9.83 and 6.89 µg/mL, respectively; P < 0.05). Unfortunately, our allele-specific PCR experiments did not reveal any significant differences in allele frequency between women with RPL and NCBI allele frequencies. CONCLUSION: This study demonstrates that adiponectinemia is increased in patients suffering from RPL. However, association of adiponectin with adverse pregnancy outcomes remains to be elucidated.

Are de novo rea(21;21) chromosomes really de novo?

We report a rare case of recurrent trisomy 21 caused by an isochromosome 21q and what is very likely to be maternal germ-line cell mosaicism. Over 90% of cases of rob(21;21) reported in the literature are due to an isochromosome 21q, with a risk of recurrence of more than 10%.

Prevalence of recurrent pathogenic microdeletions and microduplications in over 9500 pregnancies.

OBJECTIVES: The implementation of chromosomal microarray analysis (CMA) in prenatal testing for all patients has not achieved a consensus. Technical alternatives such as Prenatal BACs-on-Beads(TM) (PNBoBs(TM) ) have thus been applied. The aim of this study was to provide the frequencies of the submicroscopic defects detectable by PNBoBs(TM) under different prenatal indications. METHODS: A total of 9648 prenatal samples were prospectively analyzed by karyotyping plus PNBoBs(TM) and classified by prenatal indication. The frequencies of the genomic defects and their 95%CIs were calculated for each indication. RESULTS: The overall incidence of cryptic imbalances was 0.7%. The majority involved the DiGeorge syndrome critical region (DGS). The additional diagnostic yield of PNBoBs(TM) in the population with a low a priori risk was 1/298. The prevalences of DGS microdeletion and microduplication in the low-risk population were 1/992 and 1/850, respectively. CONCLUSIONS: The constant a priori risk for common pathogenic cryptic imbalances detected by this technology is estimated to be ~0.3%. A prevalence higher than that previously estimated was found for the 22q11.2 microdeletion. Their frequencies were independent of maternal age. These data have implications for cell-free DNA screening tests design and justify prenatal screening for 22q11 deletion, as early recognition of DGS improves its prognosis.

Prenatal diagnosis of 24 cases of microduplication 22q11.2: an investigation of phenotype-genotype correlations.

OBJECTIVE: Microduplication 22q11.2 is primarily characterized by a highly variable clinical phenotype, which ranges from apparently normal or slightly dysmorphic features (in the presence or absence of learning disorders) to severe malformations with profound mental retardation. Hence, genetic counseling is particularly challenging when microduplication 22q11.2 is identified in a prenatal diagnosis. Here, we report on 24 prenatal cases of microduplication 22q11.2. METHODS: Seventeen of the cases were also reanalyzed by microarray analysis, in order to determine copy number variations (CNVs, which are thought to influence expressivity). We also searched for possible correlations between fetal phenotypes, indications for invasive prenatal diagnosis, inheritance, and pregnancy outcomes. RESULTS: Of the 24 cases, 15 were inherited, six occurred de novo, and three were of unknown origin. Termination of pregnancy occurred in seven cases and was mainly decided on the basis of ultrasound findings. Moreover, additional CNVs were found in some patients and we try to make a genotype-phenotype correlation. CONCLUSION: We discuss the complexity of genetic counseling for microduplication 22q11.2 and comment on possible explanations for the clinical heterogeneity of this syndrome. In particular, we assessed the co-existence of additional CNVs and their contribution to phenotypic variations in chromosome 22q11.2 microduplication syndrome.

Associations between Individual and Combined Polymorphisms of the TNF and VEGF Genes and the Embryo Implantation Rate in Patients Undergoing In Vitro Fertilization (IVF) Programs.

BACKGROUND: A multiple pregnancy is now considered to be the most common adverse outcome associated with in vitro fertilization (IVF). As a consequence, the identification of women with the best chances of embryo implantation is a challenge in IVF program, in which the objective is to offer elective single-embryo transfer (eSET) without decreasing the pregnancy rate. To date, a range of hormonal and clinical parameters have been used to optimize eSET but none have significant predictive value. This variability could be due to genetic predispositions related to single-nucleotide polymorphisms (SNPs). Here, we assessed the individual and combined impacts of thirteen SNPs that reportedly influence the outcome of in vitro fertilisation (IVF) on the embryo implantation rate for patients undergoing intracytoplasmic sperm injection program (ICSI). MATERIALS AND METHODS: A 13 gene polymorphisms: FSHR(Asn680Ser), p53(Arg72Pro), AMH(Ile49Ser), ESR2(+1730G>A), ESR1(-397T>C), BMP15(-9C>G), MTHFR1(677C>T), MTHFR2(1298A>C), HLA-G(-725C>G), VEGF(+405G>C), TNFα(-308A>G), AMHR(-482A>G), PAI-1(4G/5G), multiplex PCR assay was designed to genotype women undergoing ICSI program. We analyzed the total patients population (n = 428) and a subgroup with homogeneous characteristics (n = 112). RESULTS: Only the VEGF(+405G>C) and TNFα(-308A>G) polymorphisms impacted fertilization, embryo implantation and pregnancy rates. Moreover, the combined VEGF+405.GG and TNFα-308.AG or AA genotype occurred significantly more frequently in women with high implantation potential. In contrast, the VEGF+405.CC and TNFα-308.GG combination was associated with a low implantation rate. CONCLUSION: We identified associations between VEGF(+405G>C) and TNFα(-308A>G) polymorphisms (when considered singly or as combinations) and the embryo implantation rate. These associations may be predictive of embryo implantation and could help to define populations in which elective single-embryo transfer should be recommended (or, conversely, ruled out). However, the mechanism underlying the function of these polymorphisms in embryo implantation remains to be determined and the associations observed here must be confirmed in a larger, more heterogeneous cohort.

RHOXF2 gene, a new candidate gene for spermatogenesis failure.

INTRODUCTION: Genes involved in testicular differentiation, spermatogenesis, proliferation and apoptosis of germ cells have been shown to evolve rapidly and display rapid DNA changes. These genes are therefore good candidates for explaining impairments in spermatogenesis. Initial studies of some of these genes appear to confirm this hypothesis. The RHOXF2 candidate gene belongs to the RHOX family clustered in Xq24 and is specifically expressed in the testis. It contains four exons and codes for a 288 amino acid (aa) transcription factor. It has a high degree of homology (>99.9%) with its paralogue RHOXF2B, which is also preferentially expressed in the testis. OBJECTIVES: To sequence RHOXF2 and RHOXF2B in intracytoplasmic sperm injection (ICSI) patients and identify any single-nucleotide polymorphisms (SNPs) associated with impaired spermatogenesis. MATERIALS: A cohort of 327 patients in ICSI programmes at Poissy and Bichat hospitals. All patients gave their written, informed consent to participation. One hundred patients had unaffected spermatogenesis and 227 displayed impaired spermatogenesis. METHODS: The four exons in each of RHOXF2 and RHOXF2B were sequenced in 47 patients with oligospermia or non-obstructive azoospermia. Given that exons 2 and 3 were found to harbour most of the SNPs, only these two exons were sequenced in the remaining 280 subjects. RESULTS: Due to the extremely high degree of sequence identity between RHOXF2 and RHOXF2B, we were not able to distinguish between the sequences of these two genes. Although 9 SNPs were identified, there were no significant frequency differences between ICSI patients with normal vs. impaired spermatogenesis. Two insertions were identified: a 21-nucleotide insertion was retrieved in both groups and a guanine insertion (inducing a premature stop codon) only found in two patients with impaired spermatogenesis. CONCLUSION/OUTLOOK: RHOXF2 is a good candidate for rapid evolution by positive selection. Analysis of the polymorphism frequency in exons 2 and 3 did not allow us to correlate the identified SNPs with male infertility. However, a single nucleotide insertion was identified only in men with impaired spermatogenesis. Further work will be needed to establish whether genetic changes in RHOXF2 can give rise to defects in spermatogenesis.

INTRODUCTION: Les gènes impliqués dans la différenciation des testicules, la spermatogenèse, la prolifération et l'apoptose des cellules germinales ont été montrés comme ayant une évolution rapide de la séquence d'ADN. Ces gènes sont donc de bons candidats pour expliquer les déficiences de la spermatogenèse. Les premières études semblent confirmer cette hypothèse. Le gène RHOXF2, appartenant à la famille des gènes RHOX avec un cluster dans Xq24, est un bon candidat car spécifiquement exprimé dans les testicules. Ce gène a un degré élevé d'homologie (> 99,9%), avec son paralogue RHOXF2B , qui est également exprimé préférentiellement dans les testicules. OBJECTIFS: Séquencer RHOXF2 chez des patients infertiles bénéficiant d'une injection intracytoplasmique de spermatozoïdes (ICSI) afin d'identifier des polymorphismes associés à une déficience de la spermatogenèse. MATÉRIELS: Une cohorte de 327 patients inclus dans un programme d'ICSI. Tous les patients ont donné leur consentement écrit et éclairé à la participation de cette étude. Cent patients n'avaient pas d'altération de la spermatogenèse et 227 avaient une déficience. MÉTHODES: Les quatre exons de RHOXF2 ont été séquencés chez 47 patients présentant une oligospermie ou une azoospermie non obstructive. Étant donné que les exons 2 et 3 ont été trouvés comme ayant le plus de SNPs, seuls ces deux exons ont été séquencés dans les 280 sujets restants. RÉSULTATS: Bien que 9 SNPs aient été identifiés, il n'y avait pas de différence de fréquences significatives entre les patients ayant une altération, ou non de la spermatogenèse. Deux insertions ont été identifiées: une insertion de 21 nucléotides retrouvées dans les deux groupes et une insertion d'une guanine (induisant un codon stop prématuré) chez deux patients présentant une altération de la spermatogenèse. CONCLUSION: RHOXF2 est un bon candidat pour une évolution rapide par sélection positive. L'analyse de la fréquence des polymorphismes dans les exons 2 et 3 ne nous permet pas actuellement de corréler les SNP identifiés avec l'infertilité masculine. Cependant, une insertion d'un seul nucléotide a été identifiée uniquement chez des hommes avec une déficience de la spermatogenèse. Des travaux complémentaires seront nécessaires pour déterminer l'impact du gène RHOXF2 sur la spermatogenèse.

High-magnification sperm selection does not decrease the aneuploidy rate in patients who are heterozygous for reciprocal translocations.

PROBLEM: This study sought to evaluate the value of motile sperm organelle morphology examination (MSOME) for selecting euploid spermatozoa in six patients who were heterozygous for a reciprocal translocation. METHOD OF STUDY: We used sperm fluorescence in situ hybridization (FISH) to screen for aneuploidy of the chromosomes involved in the translocations and a putative interchromosomal effect (ICE) for chromosomes 18, X and Y. This procedure was performed on (i) whole sperm (i.e. no selection) and on normal spermatozoa selected (ii) at a magnification typically used for intracytoplasmic sperm injection (ICSI), referred to as "ICSI-like", and (iii) with MSOME. RESULTS: The balanced translocation rates did not differ significantly (p=0.81) when comparing whole sperm (57.2 %) with spermatozoa after ICSI-like selection (56.3 %) or after MSOME (53.7 %). Similarly, the aneuploidy rates for ICEs did not differ significantly (p=0.14) when comparing whole sperm (1.9 %), ICSI-selected spermatozoa (3.4 %) and MSOME-selected spermatozoa (1.0 %). CONCLUSION: For patients who are heterozygous for reciprocal translocations, MSOME does not improve the selection of euploid spermatozoa.

Can one translocation impact the meiotic segregation of another translocation? A sperm-FISH analysis of a 46,XY,t(1;16)(q21;p11.2),t(8;9) (q24.3;p24) patient and his 46,XY,t(8;9)(q24.3;p24) brother and cousin.

Individuals with two independent chromosome rearrangements are rare and meiotic segregation studies are few. Two brothers (P1 and P2) and a cousin (P3) were karyotyped and found to have the same familial reciprocal translocation between the long arm of chromosome 8 and the short arm of chromosome 9: 46,XY,t(8;9)(q24.3;p24). In addition, one brother also had a different de novo reciprocal translocation between the long arm of chromosome 1 and the short arm of chromosome 16: 46,XY,t(1;16)(q21;p11.2)dn,t(8;9)(q24.3;p24)mat. Using locus-specific probes for segments involved in the translocations and for other chromosomes, sperm-FISH analysis was used to investigate the products of meiotic segregation of the translocations and the possibility of an interchromosomal effect (ICE). Sperm nucleus fragmentation was also evaluated. For the t(8;9) translocation, the proportion of unbalanced products was higher for P1 (66.3%, P < 0.0001) than P2 (51.9%) and P3 (50.4%), and the proportion consistent with each meiosis I segregation mode was also different for P1. In addition, for P1, 61.6% of the products of the t(1;16) were unbalanced, and 85.6% of spermatozoa overall included both translocations. No evidence of an ICE was found and sperm nucleus fragmentation rates were similar. Our study suggests that co-segregation of the t(8;9) and the t(1;16) resulted in modifying the proportions of t(8;9) meiotic segregation products found in spermatozoa. This could be due to selection associated with meiotic checkpoints and germ cell death.

The vascular endothelial growth factor (VEGF) +405 G/C polymorphism and its relationship with recurrent implantation failure in women in an IVF programme with ICSI.

PURPOSE: Successful embryo implantation depends on trophoblast proliferation, migration and, lastly, invasion of the endometrium (to anchor the trophoblast to the uterus). This invasion is mediated by locally produced soluble factors. Of these, vascular endothelial growth factor (VEGF) is the best characterized regulator of angiogenesis. Here, we investigate the association between the VEGF + 405 C/G genotype and the recurrence of embryo implantation failure in women undergoing in vitro fertilization (IVF) program with intracytoplasmic sperm injection (ICSI). METHODS: Forty women with recurrent implantation failure defined by absence of pregnancy after transfer of more than 10 embryos and 131 women control, with at least one live birth after the transfer of fewer than 10 embryos were included. Genomic DNA was analysed with an allele-specific polymerase chain reaction and a Chi-2 test was used to compare the respective VEGF + 405 C/G genotype frequencies in cases and controls. RESULTS: The frequency of the VEGF +405C/C genotype was higher in women with recurrent implantation failure after ICSI-embryo transfer than in controls (17.5 % and 5.3 %, respectively, p = 0.01). CONCLUSION: The VEGF +405 G/C polymorphism may influence embryo implantation and VEGF + 405 C/C genotype may predispose to recurrent implantation failure after ICSI-ET.

Genetic polymorphisms influence the ovarian response to rFSH stimulation in patients undergoing in vitro fertilization programs with ICSI.

INTRODUCTION: Obtaining an adequate number of high-quality oocytes is a major challenge in controlled ovarian hyperstimulation (COH). To date, a range of hormonal and clinical parameters have been used to optimize COH but none have significant predictive value. This variability could be due to the genetic predispositions of single-nucleotide polymorphisms (SNPs). Here, we assessed the individual and combined impacts of thirteen SNPs that reportedly influence the outcome of in vitro fertilisation (IVF) on the ovarian response to rFSH stimulation for patients undergoing intracytoplasmic sperm injection program (ICSI). RESULTS: Univariate analysis revealed that only FSHR, ESR2 and p53 SNPs influenced the number of mature oocytes. The association was statistically significant for FSHR (p=0.0047) and ESR2 (0.0017) in the overall study population and for FSHR (p=0.0009) and p53 (p=0.0048) in subgroup that was more homogeneous in terms of clinical variables. After Bonferroni correction and a multivariate analysis, only the differences for FSHR and ESR2 polymorphisms were still statistically significant. In a multilocus analysis, only the FSHR and AMH SNP combination significantly influenced oocyte numbers in both population (p<0.01). DISCUSSION: We confirmed the impact of FSHR and ESR2 polymorphisms on the IVF outcome. Furthermore, we showed for the first time that a p53 polymorphism (which is already known to impact embryo implantation) could influence the ovarian response. However, given that this result lost its statistical significance after multivariate analysis, more data are needed to draw firm conclusions. Only the FSHR and AMH polymorphism combination appears to influence mature oocyte numbers but this finding also needs to be confirmed. MATERIALS AND METHODS: A 13 gene polymorphisms: FSHR(Asn680Ser), p53(Arg72Pro), AMH(Ile49Ser), ESR2(+1730G>A), ESR1(-397T>C), BMP15(-9C>G), MTHFR1(677C>T), MTHFR2(1298A>C), HLA-G(-725C>G), VEGF(+405G>C), TNFα(-308A>G), AMHR(-482 A>G), PAI-1 (4 G/5 G), multiplex PCR assay was designed to genotype women undergoing ICSI program. We analyzed the overall study population (n=427) and a subgroup with homogeneous characteristics (n=112).

Sperm FISH analysis of a 46,XY,t(3;6)(p24;p21.2),inv (8)(p11;2q21.2) double chromosomal rearrangement.

A complex chromosome rearrangement (CCR) can be defined as a structural chromosomal aberration that involves at least three breakpoints located on two or more chromosomes. Highly unbalanced gametes may lead to infertility or congenital malformations. Here is reported a double rearrangement considered as the simplest possible CCR and, in a sense, not a true CCR, meiotic segregation for a 46,XY,t(3;6)(p24;p21.2),inv(8)(p11;2q21.2) male patient referred after his partner had undergone three early miscarriages. Sperm fluorescence in-situ hybridization was used to screen for translocation and inversion segregation and an interchromosomal effect (ICE) for 13 chromosomes not involved in CCR. The malsegregation rates for the reciprocal translocation and pericentric inversion were 61.2% and 1.7%, respectively. ICE analysis revealed that the observed chromosome aneuploidy rates of between 0.1% and 0.8% did not differ significantly from control values. A slight increase in cumulative ICE (P=0.049) was observed in the patient, relative to control spermatozoa (with rates of 4.6% and 3.1%). The sperm DNA fragmentation rate differed significantly from control values (5.0%; P=0.001). Reciprocal translocation had no impact on meiotic segregation of the pericentric inversion in this double rearrangement. No conclusion could be drawn regarding the impact of pericentric inversion on translocation.

Williams-Beuren syndrome: the prenatal phenotype.

Using prenatal BACs-on-Beads technology, the first prenatal case of Williams-Beuren syndrome (WBS) was diagnosed. In light of this result, an ultrasound scan confirmed the presence of well-characterized features of WBS. This case report emphasizes the fact that new genomic technologies will generate prenatal information and provide helpful additional information.

Are zona pellucida laser drilling and polar body biopsy safe for in vitro matured oocytes?

INTRODUCTION: Preconception diagnosis requires first polar body biopsy. When the hole in the zona pellucida is made with a laser beam, heat propagation could, like the biopsy itself, be deleterious. Our aim was to evaluate the effect of this technique on human in vitro matured oocyte and embryo development. METHODS: One hunded fifty five retrieved immature oocytes from 75 women, matured in vitro, were distributed in 3 groups: 50 oocytes in a control group, without laser drilling and first polar body biopsy, 52 oocytes in a group with only laser drilling, and 53 oocytes in a group with both laser drilling and first polar body biopsy. Safety was evaluated using four criteria: [1] oocyte lysis rate, [2] oocyte activation rate, [3] oocyte development after calcium ionophore treatment, [4] and embryo chromosome breakage incidence after Tarkowski preparation. RESULTS: No difference in the four criteria was observed between the 3 oocyte groups. CONCLUSIONS: We did not find evidence of deleterious effect of laser drilling and first polar body biopsy on in vitro matured oocytes, according to our criteria.

[Contribution of first polar body analysis to understanding of human aneuploidy mechanism]. / Contribution de l'analyse du premier globule polaire à la compréhension du mécanisme des aneuploïdies humaines.

In our species, reproduction failure rate is high. Clinical evidence is miscarriage where chromosomal origin was largely involved (66% of cases). The development of assisted reproduction techniques made possible to analyse unfertilized oocytes and preimplantation embryos. The results have shown a high rate of chromosome abnormalities before implantation (50%). Two mechanisms were identified which could generate aneuploidy, the meiosis non-disjunction and the premature separation of sister chromatids (PSSC). A FISH analysis of the first polar body, a cell complementary to the oocyte after meiosis, can be performed before intracytoplasmic sperm injection. We studied 2 distinct populations (patients over 38 years old and patients with recurrent implantation failure) and we confirmed that PSSC is the major mechanism linked to advanced maternal age in human.