P-553 Response to controlled ovarian stimulation and preimplantation genetic testing for molecular disease (PGT-M) outcomes for Myotonic dystrophy type I (DM1) : A French multicentric study

Study question

Does ovarian response to controlled ovarian hyperstimulation (COH) is altered in female affected by DM1 ?

Summary answer

Ovarian response to COH is not altered in female affected by DM1 as compared to partners of affected males

What is known already

Myotonic dystrophy type 1 is the most common adult muscular dystrophy caused by a CTG trinucleotide repeat expansion which may expand across generation. As this pathology presents an autosomal dominant inheritance, PGT may be an option to achieve a pregnancy with healthy baby. There are conflicting reports about response to COH for affected female. Moreover, few data are available concerning the chance to have a healthy baby after PGT for couple with one member affected by DM1

Study design, size, duration

The present study is a retrospective observational study carried out from January 2006 through January 2020. This multicentric study was conducted in all the five centers performing PGT-M in France.

Participants/materials, setting, methods

A total of 229 couples started at least one COH cycle for the PGT procedure. The patient carrying the mutation was the female for 178 couples and the male for the 51 others. Overall, 648 COH cycles started and 560 oocytes retrieval for subsequent PGT were performed (430 for affected female and 130 for affected male). Parameters of ovarian response and PGT outcomes were compared according to the member affected by DM1.

Main results and the role of chance

Age and BMI at the first COH cycle were not significantly different between both group but female carried mutation presented lower AMH level than partner of affected male. The starting and total doses of gonadotrophin were significantly higher for mutated females. The number of retrieved and mature oocytes per cycle were not statistically different (12 [8–16] versus 11 [8–16] retrieved oocytes, p = 0.63 and 9 [6–13] versus 9 [6-13] mature oocytes, p = 0.73, respectively). In both group, more than 70% of oocyte retrieval led to embryo biopsy.

The proportion of started cycle allowing the obtention of at least one healthy embryo was significantly lower when the female was affected with DM1 (58.6% vs 70.4%, p = 0.012). In the female affected group, 49.7% of the cycles with oocytes retrieval lead to a fresh embryo transfer and a subsequent live birth rate per transfer of 21.4%. These results were not statistically different from the couple with affected male (58.5% of cycles with fresh embryo transfer (p = 0.08) and 23.6% live birth rate per transfer).

Overall, after fresh or frozen embryo transfer, 30.8% of females with DM1and 41.2% of parter of affected males had at least one live birth from PGT.

Limitations, reasons for caution

This a retrospective study included patients who were selected ovarian reserve parameters before PGT process. Moreover, the large time of inclusion may influence our conclusion.

Wider implications of the findings

Information provided herein extends knowledge about the current state of COH for DM1 affected female. Moreover, PGT results presented here allow to provide patients with proposer counseling before starting PGT process.

Trial registration number

CEROG-2020-GYN-0603

Genetic counseling for cystic fibrosis: A basic model with new challenges

While the goals of genetic counseling for cystic fibrosis - delivering relevant information on the risk of recurrence and nondirectional support of couples at risk in their reproductive choices - have not changed fundamentally, the practice has evolved considerably in the last decade, growing more complex to face new challenges but also proving more effective. Many factors have contributed to this evolution: technical progress in the exploration of the genome (new generation sequencing) and in reproductive medicine, but also societal developments promoting access to genetic information and the professionalization of genetic counselors in France. The prospect of expanded pre-conception screening of at-risk couples makes genetic counselors major actors not only in medical care centers, but also in modern society by contributing to genetic education among citizens. © 2020 French Society of Pediatrics. Published by Elsevier Masson SAS. All rights reserved.

A Broad Test Based on Fluorescent-Multiplex PCR for Noninvasive Prenatal Diagnosis of Cystic Fibrosis

BACKGROUND

Analysis of cell-free fetal DNA in maternal plasma is very promising for early diagnosis of monogenic diseases. However, it has been limited by the need to set up patient- or disease-specific custom-made approaches. Here we propose a universal test based on fluorescent multiplex PCR and size fragment analysis for an indirect diagnosis of cystic fibrosis (CF).

METHODS

The test, based on haplotyping, includes nine intra- and extragenic short tandem repeats of the CFTR locus, the coamplification of p.Phe508del (the most frequent mutation in CF patients worldwide), and a specific SRY sequence. The assay is able to determine the inherited paternal allele.

RESULTS

Our simple approach was successfully applied to 30 couples and provided clear results from the maternal plasma. The mean rate of informative markers was sufficient to propose it for use in indirect diagnosis.

CONCLUSIONS

This noninvasive prenatal diagnosis test, focused on indirect diagnosis of CF, offers many advantages over current methods: it is simple, rapid, and cost-effective. It allows for the testing of a large number of couples with high risk of CF, whatever the familial mutation of the CFTR gene. It provides an alternative method to reduce the number of invasive tests.

Thirteen years' experience of 893 PGD cycles for monogenic disorders in a publicly funded, nationally regulated regional hospital service

This study provides an overview of preimplantation genetic diagnosis (PGD) for single gene diseases and the management of expanding indications in the context of a fully financially covered service at Montpellier's regional hospital centre. Within the framework of a restrictive law ruling PGD in France, only the parental genetic risk can be studied in embryos (concurrent aneuploidy screening is not allowed). PCR-based techniques were developed combining mutation detection and closely linked short tandem repeat markers within or flanking the affected genes, and set up more than 100 different robust fluorescent multiplex assays for 61 monogenic disorders. This strategy was used to analyse blastomeres from cleavage-stage embryos. Overall, 893 cycles were initiated in 384 couples; 727 cycles proceeded to oocyte retrieval and 608 cycles to embryo transfer, resulting in 184 deliveries. Clinical pregnancy rate per transfer, implantation and miscarriage rates were 33.6%, 25.1% and 8.8%, respectively. Our PGD programme resulted in the birth of 214 healthy babies for 162 out of 358 couples (45.3%), constituting a relevant achievement within an organizational framework that does not allow aneuploidy screening but provides equal access to PGD, both geographically and socioeconomically. This is a rare example of a fully free-of-charge PGD service.

Cervical cancer screening in low-resource settings: a smartphone image application as an alternative to colposcopy

BACKGROUND

Visual inspection after application of acetic acid (VIA) and Lugol's iodine (VILI) is a cervical cancer (CC) screening approach that has recently been adopted in low- and middle-income countries (LMIC). Innovative technologies allow the acquisition of consecutive cervical images of VIA and VILI using a smartphone application. The aim of this study was to evaluate the quality of smartphone images in order to assess the feasibility and usability of a mobile application for CC screening in LMIC.

METHODS

Between May and November 2015, women aged 30-65 years were recruited in a CC screening campaign in Madagascar. Human papillomavirus-positive women were invited to undergo VIA/VILI assessment. Pictures of their cervix were taken using a Samsung Galaxy S5 with an application called "Exam", which was designed to obtain high-quality images and to classify them in the following sequence: native, VIA, VILI and posttreatment. Experts in colposcopy were asked to evaluate if the quality of the pictures was sufficient to establish the diagnosis and to assess sharpness, focus and zoom.

RESULTS

The application use was simple and intuitive, and 208 pictures were automatically classified and recorded in the patient's file. The quality was judged as adequate for diagnosis in 93.3% of cases. The interobserver agreement was κ =0.45 (0.23-0.58), corresponding to a moderate agreement on the common scale of kappa values.

CONCLUSION

This smartphone application allows the acquisition of good quality images for VIA/VILI diagnosis. The classification of images in a patient database makes them accessible to on- and off-site experts, and allows continuous clinical education. Smartphone applications may offer an alternative to colposcopy for CC screening in LMIC.

Germline mosaicism is a pitfall in PGD for X-linked disorders. Single sperm typing detects very low frequency paternal gonadal mosaicism in a case of recurrent chondrodysplasia punctata misattributed to a maternal origin

This manuscript presents a molecularly demonstrated gonadal mosaicism from paternal origin for X-linked dominant chondrodysplasia punctata by single sperm typing. A couple who had experienced two medical terminations of pregnancy of female fetuses was referred to our pre-implantation genetic diagnosis (PGD) centre with the diagnosis of maternally derived gonadal mosaicism. Indeed, genetic analyses of different DNA samples - including semen - from the healthy parents failed to detect the variant found in the fetuses. Six embryos, all male, were obtained during the PGD cycle. The causative variant was not detected in any embryo, whereas five embryos had inherited the 'at-risk' maternal haplotype. The assumption of a maternal gonadal mosaicism was still possible, but this finding allowed us to consider the possibility of a paternal rather than maternal gonadal mosaicism. It prompted us to perform extensive single sperm analyses, demonstrating a low-frequency paternal germline mosaicism, which led to completely different haplotype phasing and PGD counselling. In conclusion, this case further exemplifies that germline mosaicism is a pitfall in PGD where diagnosis largely relies on linkage analysis and suggests that tracing the parental inheritance through polar body analysis and/or single sperm typing experiments is of major importance for adequate genetic counselling and accurate PGD. © 2016 John Wiley & Sons, Ltd.

The improvement of the best practice guidelines for preimplantation genetic diagnosis of cystic fibrosis: toward an international consensus

Cystic fibrosis (CF) is one of the most common indications for preimplantation genetic diagnosis (PGD) for single gene disorders, giving couples the opportunity to conceive unaffected children without having to consider termination of pregnancy. However, there are no available standardized protocols, so that each center has to develop its own diagnostic strategies and procedures. Furthermore, reproductive decisions are complicated by the diversity of disease-causing variants in the CFTR (cystic fibrosis transmembrane conductance regulator) gene and the complexity of correlations between genotypes and associated phenotypes, so that attitudes and practices toward the risks for future offspring can vary greatly between countries. On behalf of the EuroGentest Network, eighteen experts in PGD and/or molecular diagnosis of CF from seven countries attended a workshop held in Montpellier, France, on 14 December 2011. Building on the best practice guidelines for amplification-based PGD established by ESHRE (European Society of Human Reproduction and Embryology), the goal of this meeting was to formulate specific guidelines for CF-PGD in order to contribute to a better harmonization of practices across Europe. Different topics were covered including variant nomenclature, inclusion criteria, genetic counseling, PGD strategy and reporting of results. The recommendations are summarized here, and updated information on the clinical significance of CFTR variants and associated phenotypes is presented.

Preimplantation genetic diagnosis for cystic fibrosis: the Montpellier center's 10-year experience

This study provides an overview of 10 years of experience of preimplantation genetic diagnosis (PGD) for cystic fibrosis (CF) in our center. Owing to the high allelic heterogeneity of CF transmembrane conductance regulator (CFTR) mutations in south of France, we have set up a powerful universal test based on haplotyping eight short tandem repeats (STR) markers together with the major mutation p.Phe508del. Of 142 couples requesting PGD for CF, 76 have been so far enrolled in the genetic work-up, and 53 had 114 PGD cycles performed. Twenty-nine cycles were canceled upon in vitro fertilization (IVF) treatment because of hyper- or hypostimulation. Of the remaining 85 cycles, a total of 493 embryos were biopsied and a genetic diagnosis was obtained in 463 (93.9%), of which 262 (without or with a single CF-causing mutation) were transferable. Twenty-eight clinical pregnancies were established, yielding a pregnancy rate per transfer of 30.8% in the group of seven couples with one member affected with CF, and 38.3% in the group of couples whose both members are carriers of a CF-causing mutation [including six couples with congenital bilateral absence of the vas deferens (CBAVD)]. So far, 25 children were born free of CF and no misdiagnosis was recorded. Our test is applicable to 98% of couples at risk of transmitting CF.

New multiplex PCR-based protocol allowing indirect diagnosis of FSHD on single cells: can PGD be offered despite high risk of recombination?

Molecular pathophysiology of facioscapulohumeral muscular dystrophy (FSHD) involves the heterozygous contraction of the number of tandemly repeated D4Z4 units at chromosome 4q35.2. FSHD is associated with a range of 1-10 D4Z4 units instead of 11-150 in normal controls. Several factors complicate FSHD molecular diagnosis, especially the cis-segregation of D4Z4 contraction with a 4qA allele, whereas D4Z4 shortening is silent both on alleles 4qB and 10q. Discrimination of pathogenic 4q-D4Z4 alleles from highly homologous 10q-D4Z4 arrays requires the use of the conventional Southern blot, which is not suitable at the single-cell level. Preimplantation genetic diagnosis (PGD) is a frequent request from FSHD families with several affected relatives. We aimed to develop a rapid and sensitive PCR-based multiplex approach on single cells to perform an indirect familial segregation study of pathogenic alleles. Among several available polymorphic markers at 4q35.2, the four most proximal (D4S2390, D4S1652, D4S2930 and D4S1523, <1.23 Mb) showing the highest heterozygote frequencies (67-91%) were selected. Five recombination events in the D4S2390-D4S1523 interval were observed among 144 meioses. In the D4S2390-D4Z4 interval, no recombination event occurred among 28 FSHD meioses. Instead, a particular haplotype segregated with both clinical and molecular status, allowing the characterization of an at-risk allele in each tested FSHD family (maximal LOD score 2.98 for theta=0.0). This indirect protocol can easily complement conventional techniques in prenatal diagnosis. Although our multiplex PCR-based approach technically fulfils guidelines for single-cell analysis, the relatively high recombination risk hampers its application to PGD.

Efficient strategies for preimplantation genetic diagnosis of spinal muscular atrophy

OBJECTIVE

To develop and apply efficient multiplex preimplantation genetic diagnosis (PGD) protocols for spinal muscular atrophy (SMA).

DESIGN

Two multiplex PGD protocols were developed allowing the detection of the common homozygous deletion of the telomeric spinal muscular atrophy gene (SMN1), together with two microsatellites located on each side of SMN1.

SETTING

The molecular genetics laboratory of the university hospital in Montpellier.

PATIENT(S)

A couple who had already given birth to a child affected with SMA.

INTERVENTION(S)

In vitro fertilization using intracytoplasmic sperm injection (ICSI) and blastomere biopsy.

MAIN OUTCOME MEASURE(S)

Improvement of PGD for SMA.

RESULT(S)

Two different multiplex protocols were set up on 81 (multiplex A) and 64 single cells (multiplex B) from normal controls, affected patients, and individuals with homozygous SMN2 deletion. In one PGD cycle that used one of these protocols, two embryos were transferred, which resulted in the birth of a healthy baby.

CONCLUSION(S)

Analysis of microsatellite markers in addition to the SMN1 deletion allows the detection of contamination, the study of ploidy of the biopsied blastomeres, and the performance of an indirect genetic diagnosis, thereby increasing the reliability of the results. This PGD assay may be applied to all families with the common deletion of SMN1 and also to couples in whom one of the partners carries a small intragenic mutation in SMN1, identified in about 6% of affected individuals who do not lack both copies of SMN1.

Large genomic rearrangements in the CFTR gene contribute to CBAVD

Background

By performing extensive scanning of whole coding and flanking sequences of the CFTR (Cystic Fibrosis Transmembrane Conductance Regulator) gene, we had previously identified point mutations in 167 out of 182 (91.7%) males with isolated congenital bilateral absence of the vas deferens (CBAVD). Conventional PCR-based methods of mutation analysis do not detect gross DNA lesions. In this study, we looked for large rearrangements within the whole CFTR locus in the 32 CBAVD patients with only one or no mutation.

Methods

We developed a semi-quantitative fluorescent PCR assay (SQF-PCR), which relies on the comparison of the fluorescent profiles of multiplex PCR fragments obtained from different DNA samples. We confirmed the gross alterations by junction fragment amplification and identified their breakpoints by direct sequencing.

Results

We detected two large genomic heterozygous deletions, one encompassing exon 2 (c.54-5811_c.164+2186del8108ins182) [or CFTRdele2], the other removing exons 22 to 24 (c.3964-3890_c.4443+3143del9454ins5) [or CFTRdele 22_24], in two males carrying a typical CBAVD mutation on the other parental CFTR allele. We present the first bioinformatic tool for exon phasing of the CFTR gene, which can help to rename the exons and the nomenclature of small mutations according to international recommendations and to predict the consequence of large rearrangements on the open reading frame.

Conclusion

Identification of large rearrangements further expands the CFTR mutational spectrum in CBAVD and should now be systematically investigated. We have designed a simple test to specifically detect the presence or absence of the two rearrangements identified in this study.

Strategies for preimplantation genetic diagnosis of Angelman syndrome caused by mutations in the UBE3A gene

Angelman syndrome (AS) is a neurodevelopmental disorder associated with the loss of maternal gene expression in chromosome region 15q11-q13. AS is caused by a wide variety of genetic mechanisms, including mutations in the UBE3A gene that have been identified in 10-15% of patients; when the mother is heterozygous for the causative mutation, the risk of recurrence in subsequent pregnancies is 50%. The present authors have developed a preimplantation genetic diagnosis (PGD) assay for a family displaying a 10 bp deletion in exon 9 of the UBE3A gene, which was shared by two affected children and their phenotypically normal mother. A duplex polymerase chain reaction protocol was established, allowing the efficient amplification of the mutation together with an informative microsatellite marker (D15S122) located in intron 1 of the UBE3A gene. As most of UBE3A mutations identified so far are unique to one family, the present authors have also developed an indirect single cell protocol based upon the co-amplification of two microsatellite markers located within (D15S122) and close to the UBE3A gene (D15S1506). This strategy may be applied to all informative families requesting PGD for Angelman syndrome associated with mutations in the UBE3A gene.

Specific detection of deleted and non-deleted dystrophin exons together with gender assignment in preimplantation genetic diagnosis of Duchenne muscular dystrophy

We have developed a preimplantation genetic diagnosis (PGD) strategy for Duchenne muscular dystrophy (DMD) allowing the simultaneous amplification of four exons (6, 8, 28 and 32) of the dystrophin gene together with ZFX/ZFY genes for gender determination. Preliminary experiments were carried out on 215 single lymphocytes from male and female individuals. Amplification rates ranged from 90.2% for exon 6 to 96.7% for exons 8 and 32. At least four of the five sequences were successfully amplified in 95.8% of single cells, and sexing was possible in 98.5%. This 5-plex assay was found to be robust enough to be used in a PGD clinical procedure and was therefore applied to a family whose female partner was a heterozygous carrier of a large deletion extending from exon 21 to exon 34 of the dystrophin gene. We have thus analysed two exons located in the deleted region of the gene, two non-deleted exons used as intrasample controls, and ZFX/ZFY genes. Cleavage stage embryo biopsy followed by PCR resulted in transfer of three unaffected embryos. The advantage of the present approach is to identify and subsequently transfer unaffected male embryos in addition to female embryos, and is now applicable to all families displaying a deletion involving at least one of these exons.

Rapid detection of the deltaF508 mutation in single cells using DHPLC: implications for preimplantation genetic diagnosis

PURPOSE

Practice of preimplantation genetic diagnosis (PGD) requires efficient amplification and analysis techniques. We have tested Denaturing High Performance Liquid Chromatography (DHPLC) to screen the deltaF508 mutation in heterozygous single cells in order to assess its usefulness for PGD of cystic fibrosis.

METHODS

One hundred and two single lymphocytes--including N/N and N/deltaF508--were studied. F508 locus was amplified by nested PCR followed by the analysis of PCR products by DHPLC in non-denaturing conditions.

RESULTS

On the basis of PCR-amplified product analysis, total efficiency of amplification was 98.78% (101/102), and allele dropout (ADO) rate was 3.7% (3/81). For each sample, results were obtained in less than 4 min with high resolution.

CONCLUSIONS

DHPLC is a rapid and efficient technique to detect the deltaF508 mutation in single cells and is therefore appropriate for clinical application of preimplantation genetic diagnosis of cystic fibrosis.

First preimplantation genetic diagnosis of hereditary retinoblastoma using informative microsatellite markers

Retinoblastoma is a malignant intra-ocular tumour of developing retina initiated by inactivation of both alleles of the retinoblastoma susceptibility (RB1) gene. This paper reports the first clinical experience of preimplantation genetic diagnosis (PGD) for hereditary retinoblastoma using two highly polymorphic microsatellite markers RB1.20 and D13S284, located within and close to the RB1 gene respectively. Duplex PCRs were tested on more than 300 single lymphocytes from heterozygous individuals at both loci, in order to test the accuracy and reliability of the single-cell protocol. This procedure requires a nested PCR and the analysis of fluorescently labelled PCR products on an automatic DNA sequencer. Amplification efficiency and allele drop-out rates ranged from 96.7 to 98.4%, and 3.7 to 5.4% respectively. This test was found to be accurate and reliable enough to be applied to the study of human blastomeres. Subsequently, this approach was used in a PGD treatment cycle for a couple who already had a child affected with hereditary retinoblastoma and found to be informative for both microsatellite markers.

Meiotic segregation analysis of RB1 alleles in retinoblastoma pedigrees by use of single-sperm typing

In hereditary retinoblastoma, different epidemiological studies have indicated a preferential paternal transmission of mutant retinoblastoma alleles to offspring, suggesting the occurrence of a meiotic drive. To investigate this mechanism, we analyzed sperm samples from six individuals from five unrelated families affected with hereditary retinoblastoma. Single-sperm typing techniques were performed for each sample by study of two informative short tandem repeats located either in or close to the retinoblastoma gene (RB1). The segregation probability of mutant RB1 alleles in sperm samples was assessed by use of the SPERMSEG program, which includes experimental parameters, recombination fractions between the markers, and segregation parameters. A total of 2,952 single sperm from the six donors were analyzed. We detected a significant segregation distortion in the data as a whole (P=.0099) and a significant heterogeneity in the segregation rate across donors (.0092). Further analysis shows that this result can be explained by segregation distortion in favor of the normal allele in one donor only and that it does not provide evidence of a significant segregation distortion in the other donors. The segregation distortion favoring the mutant RB1 allele does not seem to occur during spermatogenesis, and, thus, meiotic drive may result either from various mechanisms, including a fertilization advantage or a better mobility in sperm bearing a mutant RB1 gene, or from the existence of a defectively imprinted gene located on the human X chromosome.

Direct estimation of the recombination frequency between the RB1 gene and two closely linked microsatellites using sperm typing

In this study, single sperm typing has been used for high-resolution recombination analysis between the retinoblastoma gene and two closely linked extragenic microsatellites (D13S284 and D13S1307). The analysis of 1198 single sperm from three donors allowed the determination of recombination fractions between RB1.20 and D13S284 and RB1.20 and D13S1307 of 0.022 and 0.033, respectively. These results show that RB1 gene and the two microsatellites are closely linked, which validates their potential use in indirect genetic diagnosis of retinoblastoma.

Refinement of genetic localization of the Alström syndrome on chromosome 2p12-13 by linkage analysis in a North African family

Alström syndrome is a rare autosomal recessive disorder characterized by retinal pigment degeneration, neurogenic deafness, infantile obesity, hyperlipidemia, and non-insulin-dependent diabetes mellitus. While the disease-related gene remains unknown, studies of the genetic isolate of French Acadians provisionally locate the Alström syndrome on chromosome 2p12-13 within a 14.9-cM interval. To confirm this finding in another ethnic population and refine the candidate region we investigated by linkage analysis a consanguineous family of North African origin, in which three of seven siblings displayed all major neurological and metabolic features of Alström syndrome. Genotyping was performed on an ABI377 DNA automatic sequencer and LOD scores were obtained with the Fastlink program. Five markers previously investigated in French Acadians confirmed the involvement of the candidate region, although pairwise LOD scores were of poor significance (Zmax = 2.9). To further confirm homogeneity and refine the candidate region, 20 additional markers were investigated. Haplotype analysis and allele segregation revealed that affected children shared a single haplotype and were homozygous for the eight most centromeric markers (D2S291-D2S2114), over a 6.1-cM interval. Significative multipoint LOD scores (Zmax = 3.96) were obtained between markers D2S2110/145 and D2S286. Two clusters of known genes are present in this refined region of chromosome 2p, the most attractive candidate being the hexokinase II gene. However, except for several known polymorphisms, no mutations were detected in the coding region of this gene. In conclusion, the location of Alström syndrome on chromosome 2p12-13 is confirmed, reducing the genetic interval to 6.1 cM.

[Update on a diagnostic test for choroideremia: the protein truncation test (PTT)]

PURPOSE

The aim of this study was to define the RT-PCR-PTT parameters for CHM gene analysis and to evaluate its interest as a method for CHM mutation screening.

METHODS

The entire CHM coding region was reversed-transcribed in three overlapping cDNA segments (RT-PCR) which were amplified and further analyzed by PTT after in vitro transcription/translation.

RESULTS

This strategy enabled us to detect a truncated peptide in each of the 6 unrelated patients from southern France who were investigated. The mutation was further characterized by direct sequencing of the RT-PCR product.

CONCLUSION

In CHM gene, all conditions are present to make the RT-PCR-PTT strategy the method of choice for mutation screening. As a result of the simplified protocol described in this study, the families of the patients could benefit from accurate carrier-status assessment.

Cytogenetic analysis of meiotic segregation in sperm from two males heterozygous for reciprocal translocations using PRINS and humster techniques

The meiotic segregation patterns of 2 reciprocal translocations t(7;9)(q33;p21) and t(7;18)(q35;q11) were analyzed in sperm of 2 heterozygote carriers. Both sperm karyotyping and in situ PRINS labeling of sperm nuclei were performed on a sperm sample from each subject. Using the humster technique, 54 and 72 sperm chromosome complements were successfully analyzed for the t(7;9) and the t(7;18) respectively. The frequencies of alternate, adjacent 1, adjacent 2 and 3:1 segregations were 44.44%, 37.04%, 12.96% and 5.56% for the t(7;9) and 33.33%, 43.05%, 19.45% and 4.17% for the t(7;18). The PRINS procedure allowed the rapid screening of large samples of spermatozoa. However, alternate and adjacent 1 segregants were not discriminated because of the generation of centromeric signals. The segregation pattern was determined on 10,658 spermatozoa for the t(7;9) and 10,462 for the t(7;18). The distributions of segregants were similar to those obtained by sperm karyotyping. These data were pooled with results from 37 reciprocal translocations previously studied by sperm karyotyping and 6 recently investigated by FISH. The analysis of these compiled data demonstrates the particularity of the production of imbalances in male gametes; independent of the predisposition for a type of imbalance at term, there is a preferential production of adjacent 1 imbalance in sperm.

Incidence of chromosome 1 disomy in human sperm estimated by the primed in situ (PRINS) labeling technique

The primed in situ (PRINS) labeling technique was used to determine the rate of disomy of chromosomes 1 and 16 in sperm of two normal subjects. Two different but specific primers (alpha-satellite and satellite II) for chromosome 1 were used in parallel experiments to test the efficiency of PRINS labeling in sperm nuclei. A minimum of 10,000 sperm nuclei per chromosome primer was analyzed, leading to a total number of 41,651 scored spermatozoa. Similar rates of chromosome 1 disomy (mean values, 0.18% and 0.20%) were found in both donors when the alpha-satellite and satellite II primers were used, demonstrating the reliability of PRINS labeling on sperm nuclei. For chromosome 16, the disomy rate among the two donors ranged from 0.20% to 0.24%. This study confirms that PRINS provides a rapid and efficient method for in situ chromosomal screening of sperm nuclei.

Preimplantation embryo chromosome analysis by primed in situ labeling method

OBJECTIVE

To present the use of primed in situ labeling method in preimplantation diagnosis.

DESIGN

Double- and triple-primed in situ labeling were performed on 10 morphologically abnormal preimplantation embryos, using combinations of specific primers for chromosomes 9, 13, 16, 18, 21, X, and Y.

SETTING

Embryos were obtained from patients at the Montpellier University Hospital.

PATIENT(S)

Seven women undergoing IVF at the Montpellier University Hospital.

INTERVENTION(S)

Isolated interphase nuclei from poor quality preimplantation embryos were prepared for primed in situ labeling technique.

MAIN OUTCOME MEASURE(S)

Numerical abnormalities assessed by primed in situ labeling analysis.

RESULT(S)

Using directly fluorescent-labeled nucleotides, the labeling reaction for three chromosomes did not exceed 2.30 hours. Only three analyzed embryos appeared to be chromosomally normal. Mosaicism, aneupoidy, and haploidy were observed in the seven other embryos.

CONCLUSION(S)

The primed in situ labeling method offers a simple and reliable screening tool for gender determination and aneuploidy detection. The use of this technique may contribute to significantly improve the procedure of preimplantation diagnosis.

Rapid chromosome detection in human gametes, zygotes, and preimplantation embryos using the PRINS technique

PURPOSE

The analysis of the chromosomal constitution of human gametes and embryos is of particular importance for investigation of aneuploidy occurrence and diagnostic purposes. The PRINS method constitutes an alternative to FISH for in situ chromosomal identification. We have adapted this method to human gametes, zygotes, and preimplantation embryos.

RESULTS

Chromosome-specific labeling was obtained in gametes, zygotes, and isolated blastomeres. Simultaneous detection of two or three chromosomes can be completed in less than 3 hr using fluorochrome-labeled nucleotides.

CONCLUSIONS

The PRINS technique appears to be more efficient than FISH for detection and discrimination of alpha-satellite DNA sequences. The present study demonstrates the usefulness of PRINS for chromosomal screening and preimplantation diagnosis.

Aneuploidy detection in human sperm nuclei using PRINS technique

Rapid and specific identification of chromosomes can be attained in situ using the PRimed IN Situ (PRINS) labelling technique. We have adapted this technique to mature human sperm in combination with a protocol for simultaneous decondensation and denaturation of sperm nuclei. This strategy allowed us to obtain double labelling of human spermatozoa in a < 2-hr reaction. In the present study, we report the estimates of disomy for chromosomes 3, 7, 10, 11, and 17 on 64,642 spermatozoa from 2 normal males. The incidences of disomy ranged from 0.28-0.34%. There were no significant interindividual or interchromosomal differences in disomy rates.

Assessment of aneuploidy for chromosomes 8, 9, 13, 16, and 21 in human sperm by using primed in situ labeling technique

The incidence of aneuploidy was estimated for chromosomes 8, 9, 13, 16, and 21 in mature human spermatozoa by primed in situ (PRINS) labeling technique. This method allows us to perform a chromosome-specific detection by in situ annealing of a centromeric specific primer. A dual color PRINS protocol was adapted to human sperm. The decondensation and the denaturation of sperm nuclei were simultaneously performed by 3-M NaOH treatment. Double labeling of spermatozoa was obtained in <2 h. A total of 96,292 sperm nuclei were analyzed by two independent observers. The estimates of disomy were 0.31% for chromosome 8, 0.28% for chromosome 9, 0.28% for chromosome 13, 0.26% for chromosome 16, and 0.32% for chromosome 21. These homogeneous findings suggest an equal distribution of aneuploidies among autosomal chromosomes in males.

The PRINS technique: potential use for rapid preimplantation embryo chromosome screening

The primed in-situ labelling (PRINS) method is an alternative to in-situ hybridization for chromosomal detection based on the use of chromosome-specific oligonucleotide primers. Using this process, we have developed a simple and semi-automatic method for rapid in-situ detection of human chromosomes. The reaction was performed on a programmable temperature cycler. Specific labelling was obtained in < 2 h reaction. Double PRINS techniques were performed on six morphologically abnormal preimplantation embryos using primers specific for chromosomes 9, 16, 18, 21, X and Y. The majority of these embryos displayed chromosomal abnormalities. The present results demonstrate that PRINS may be a simple and reliable technique applicable in human preimplantation diagnosis.

Direct detection of disomy in human sperm by the PRINS technique

We report the use of the PRimedIN Situ (PRINS) labelling technique for the direct estimation of disomy rates for various chromosomes in human sperm. The PRINS technique provides a rapid and reliable method for chromosome screening since specific labelling may be obtained in less than 2 h. In the present study, the disomy rates of chromosomes 2, 5, 9, 12 and 18 were investigated. The incidences of disomy are similar for all these chromosomes, ranging from 0.27% to 0.33%. These findings suggest an equal distribution of aneuploidies among autosomes in human sperm.

FISH and PRINS, a strategy for rapid chromosome screening: application to the assessment of aneuploidy in human sperm

The co-utilization of FISH and PRINS techniques for in situ chromosome screening was tested on human sperm nuclei. We used a centromeric repeat probe specific for chromosome 4 for FISH. PRINS reactions were performed with alpha-satellite primers specific for either chromosomes 9 or chromosome 18. Double labeling was obtained and estimates of disomy rates were carried out for the three chromosomes.