Pathogenic variants in E3 ubiquitin ligase RLIM/RNF12 lead to a syndromic X-linked intellectual disability and behavior disorder

RLIM, also known as RNF12, is an X-linked E3 ubiquitin ligase acting as a negative regulator of LIM-domain containing transcription factors and participates in X-chromosome inactivation (XCI) in mice. We report the genetic and clinical findings of 84 individuals from nine unrelated families, eight of whom who have pathogenic variants in RLIM (RING finger LIM domain-interacting protein). A total of 40 affected males have X-linked intellectual disability (XLID) and variable behavioral anomalies with or without congenital malformations. In contrast, 44 heterozygous female carriers have normal cognition and behavior, but eight showed mild physical features. All RLIM variants identified are missense changes co-segregating with the phenotype and predicted to affect protein function. Eight of the nine altered amino acids are conserved and lie either within a domain essential for binding interacting proteins or in the C-terminal RING finger catalytic domain. In vitro experiments revealed that these amino acid changes in the RLIM RING finger impaired RLIM ubiquitin ligase activity. In vivo experiments in rlim mutant zebrafish showed that wild type RLIM rescued the zebrafish rlim phenotype, whereas the patient-specific missense RLIM variants failed to rescue the phenotype and thus represent likely severe loss-of-function mutations. In summary, we identified a spectrum of RLIM missense variants causing syndromic XLID and affecting the ubiquitin ligase activity of RLIM, suggesting that enzymatic activity of RLIM is required for normal development, cognition and behavior.

Preimplantation genetic testing for aneuploidy by microarray analysis of polar bodies in advanced maternal age: a randomized clinical trial

STUDY QUESTION

Does preimplantation genetic testing for aneuploidy (PGT-A) by comprehensive chromosome screening (CCS) of the first and second polar body to select embryos for transfer increase the likelihood of a live birth within 1 year in advanced maternal age women aged 36-40 years planning an ICSI cycle, compared to ICSI without chromosome analysis?

SUMMARY ANSWER

PGT-A by CCS in the first and second polar body to select euploid embryos for transfer does not substantially increase the live birth rate in women aged 36-40 years.

WHAT IS KNOWN ALREADY

PGT-A has been used widely to select embryos for transfer in ICSI treatment, with the aim of improving treatment effectiveness. Whether PGT-A improves ICSI outcomes and is beneficial to the patients has remained controversial.

STUDY DESIGN, SIZE, DURATION

This is a multinational, multicentre, pragmatic, randomized clinical trial with intention-to-treat analysis. Of 396 women enroled between June 2012 and December 2016, 205 were allocated to CCS of the first and second polar body (study group) as part of their ICSI treatment cycle and 191 were allocated to ICSI treatment without chromosome screening (control group). Block randomization was performed stratified for centre and age group. Participants and clinicians were blinded at the time of enrolment until the day after intervention.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Infertile couples in which the female partner was 36-40 years old and who were scheduled to undergo ICSI treatment were eligible. In those assigned to PGT-A, array comparative genomic hybridization (aCGH) analysis of the first and second polar bodies of the fertilized oocytes was performed using the 24sure array of Illumina. If in the first treatment cycle all oocytes were aneuploid, a second treatment with PB array CGH was offered. Participants in the control arm were planned for ICSI without PGT-A. Main exclusion criteria were three or more previous unsuccessful IVF or ICSI cycles, three or more clinical miscarriages, poor response or low ovarian reserve. The primary outcome was the cumulative live birth rate after fresh or frozen embryo transfer recorded over 1 year after the start of the intervention.

MAIN RESULTS AND THE ROLE OF CHANCE

Of the 205 participants in the chromosome screening group, 50 (24%) had a live birth with intervention within 1 year, compared to 45 of the 191 in the group without intervention (24%), a difference of 0.83% (95% CI: -7.60 to 9.18%). There were significantly fewer participants in the chromosome screening group with a transfer (relative risk (RR) = 0.81; 95% CI: 0.74-0.89) and fewer with a miscarriage (RR = 0.48; 95% CI: 0.26-0.90).

LIMITATIONS, REASONS FOR CAUTION

The targeted sample size was not reached because of suboptimal recruitment; however, the included sample allowed a 90% power to detect the targeted increase. Cumulative outcome data were limited to 1 year. Only 11 patients out of 32 with exclusively aneuploid results underwent a second treatment cycle in the chromosome screening group.

WIDER IMPLICATIONS OF THE FINDINGS

The observation that the similarity in birth rates was achieved with fewer transfers, less cryopreservation and fewer miscarriages points to a clinical benefit of PGT-A, and this form of embryo selection may, therefore, be considered to minimize the number of interventions while producing comparable outcomes. Whether these benefits outweigh drawbacks such as the cost for the patient, the higher workload for the IVF lab and the potential effect on the children born after prolonged culture and/or cryopreservation remains to be shown.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the European Society of Human Reproduction and Embryology. Illumina provided microarrays and other consumables necessary for aCGH testing of polar bodies. M.B.'s institution (UZBrussel) has received educational grants from IBSA, Ferring, Organon, Schering-Plough, Merck and Merck Belgium. M.B. has received consultancy and speakers' fees from Organon, Serono Symposia and Merck. G.G. has received personal fees and non-financial support from MSD, Ferring, Merck-Serono, Finox, TEVA, IBSA, Glycotope, Abbott and Gedeon-Richter as well as personal fees from VitroLife, NMC Healthcare, ReprodWissen, BioSilu and ZIVA. W.V., C.S., P.M.B., V.G., G.A., M.D., T.E.G., L.G., G.Ka., G.Ko., J.L., M.C.M., M.P., A.S., M.T., K.V., J.G. and K.S. declare no conflict of interest.

TRIAL REGISTRATION NUMBER

NCT01532284.

TRIAL REGISTRATION DATE

7 February 2012.

DATE OF FIRST PATIENT’S ENROLMENT

25 June 2012.

Embryo selection and democratic control

Recently, American colleagues called for a systematic collection of anonymized data on how many embryos and foetuses are deselected per institution per year, and for which conditions. These authors argued that if this information would be reported to a government agency or international body, the information would provide a baseline against which jurisdiction-specific trends in selection could be assessed. People who have disabilities, together with other key stakeholders, laypeople and experts, would then be in a position to assess the social impact of human selecting technologies and to make recommendations for action to mitigate negative effects as appropriate. However, such a systematic data collection does already exist in the Netherlands and has been in place for more than 30 years. It was first introduced to monitor the practise of prenatal diagnosis by the eight licence holders sending in all data to the Minister of Public Health, Welfare and Sports. Later, the same method was expanded to preimplantation genetic diagnosis. For 8 years, these data have been discussed in the parliament, which shows that the practice of embryo selection can indeed be kept under democratic control, albeit retrospectively.

Recent developments in genetics and medically assisted reproduction: from research to clinical applications

Two leading European professional societies, the European Society of Human Genetics and the European Society for Human Reproduction and Embryology, have worked together since 2004 to evaluate the impact of fast research advances at the interface of assisted reproduction and genetics, including their application into clinical practice. In September 2016, the expert panel met for the third time. The topics discussed highlighted important issues covering the impacts of expanded carrier screening, direct-to-consumer genetic testing, voiding of the presumed anonymity of gamete donors by advanced genetic testing, advances in the research of genetic causes underlying male and female infertility, utilisation of massively parallel sequencing in preimplantation genetic testing and non-invasive prenatal screening, mitochondrial replacement in human oocytes, and additionally, issues related to cross-generational epigenetic inheritance following IVF and germline genome editing. The resulting paper represents a consensus of both professional societies involved.

Recent developments in genetics and medically-assisted reproduction: from research to clinical applications†‡

Two leading European professional societies, the European Society of Human Genetics and the European Society for Human Reproduction and Embryology, have worked together since 2004 to evaluate the impact of fast research advances at the interface of assisted reproduction and genetics, including their application into clinical practice. In September 2016, the expert panel met for the third time. The topics discussed highlighted important issues covering the impacts of expanded carrier screening, direct-to-consumer genetic testing, voiding of the presumed anonymity of gamete donors by advanced genetic testing, advances in the research of genetic causes underlying male and female infertility, utilisation of massively-parallel sequencing in preimplantation genetic testing and non-invasive prenatal screening, mitochondrial replacement in human oocytes, and additionally, issues related to cross-generational epigenetic inheritance following IVF and germline genome editing. The resulting paper represents a consensus of both professional societies involved.

Europäische Datensammlung zur Präimplantationsdiagnostik seit 1999

Seit 25 Jahren gibt es die Präimplantationsdiagnostik (PID) als Alternative zur Pränataldiagnostik monogener, mitochondrialer und chromosomaler Erkrankungen. Nach In-vitro-Fertilisation (IVF) oder (meist) Intrazytoplasmatischer Spermieninjektion (ICSI) werden entweder Polkörperchen, Blastomere oder Ektodermzellen aus den Oozyten bzw. dem Präimplantationsembryo gewonnen, um sie einer molekularen Diagnostik zu unterziehen. Nichtbetroffene Embryonen werden ausgewählt, um sie in die Gebärmutter einzusetzen, um dadurch einen Schwangerschaftsabbruch zu verhindern.

1997 wurde das ESHRE (European Society of Human Reproduction and Embryology) PGD Consortium als Teil der ESHRE-Arbeitsgruppe für Reproduktionsgenetik mit dem Ziel gegründet, in einer Langzeitbeobachtung Effizienz und klinische Ergebnisse der PID zu erfassen. Im Dezember 1999 wurde der erste von inzwischen insgesamt 13 PID-Konsortiumsberichten veröffentlicht. Darüber hinaus wurden in den letzten Jahren (2013–2015) unpublizierte Daten von der Hälfte aller 121 Mitglieder (darunter 89 europäische) des PID-Konsortiums gesammelt.

Auch wenn die Unterschiede nicht mehr so groß sind wie früher, ist die Bandbreite der PID-Gesetzgebung, -Regelwerke und -Angebote in den einzelnen europäischen Ländern noch relativ groß. Dies hat dazu geführt, dass Patienten über die nationalen Grenzen hinweg nach medizinischer Hilfe suchen.

Zu Beginn entsprach das Indikationsspektrum mehr oder weniger demjenigen der Pränataldiagnostik. Interessanterweise wird in einigen Ländern eine zunehmende Anzahl von Tests für spätmanifeste Erkrankungen angeboten, was darauf hinweist, dass für diese Fälle die PID eher akzeptiert wird als die Pränataldiagnostik.

Die wichtigsten chromosomalen Indikationen für PID stellen die reziproken Translokationen dar (sowohl für männliche als auch für weibliche Translokationsträger).

Es ist zu beobachten, dass die Biopsie eines Embryos in sehr frühen Furchungsstadien langsam durch die Blastozystenbiopsie ersetzt wird. Die Fehlgeburtenrate ist nicht erhöht. Die Anzahl der Schwangerschaftsabbrüche ist extrem niedrig. Eine von 6 Schwangerschaften führt zur Geburt von Zwillingen und die Zahl von höheren Mehrlingsschwangerschaften ist sehr begrenzt. In einzelnen Fällen wurde von Fehldiagnosen berichtet.

Preimplantation genetic screening 2.0: the theory

During the last few years a new generation of preimplantation genetic screening (PGS) has been introduced. In this paper, an overview of the different aspects of this so-called PGS 2.0 with respect to the why (what are the indications), the when (which developmental stage, i.e. which material should be studied) and the how (which molecular technique should be used) is given. With respect to the aims it is clear that PGS 2.0 can be used for a variety of indications. However, the beneficial effect of PGS 2.0 has not been proved yet in RCTs. It is clear that cleavage stage is not the optimal stage for biopsy. Almost all advocates of PGS 2.0 prefer trophectoderm biopsy. There are many new methods that allow the study of complete aneuploidy with respect to one or more of the 24 chromosomes. Because of the improved vitrification methods, selection of fresh embryos for transfer is more and more often replaced by frozen embryo transfer. The main goal of PGS has always been the improvement of IVF success. However, success is defined by different authors in many different ways. This makes it very difficult to compare the outcomes of different studies. In conclusion, the introduction of PGS 2.0 will depend on the success of the new biopsy strategies in combination with the analysis of all 24 chromosomes. It remains to be seen which approach will be the most successful and for which specific groups of patients.

The why, the how and the when of PGS 2.0: current practices and expert opinions of fertility specialists, molecular biologists, and embryologists

STUDY QUESTION

We wanted to probe the opinions and current practices on preimplantation genetic screening (PGS), and more specifically on PGS in its newest form: PGS 2.0?

STUDY FINDING

Consensus is lacking on which patient groups, if any at all, can benefit from PGS 2.0 and, a fortiori, whether all IVF patients should be offered PGS.

WHAT IS KNOWN ALREADY

It is clear from all experts that PGS 2.0 can be defined as biopsy at the blastocyst stage followed by comprehensive chromosome screening and possibly combined with vitrification. Most agree that mosaicism is less of an issue at the blastocyst stage than at the cleavage stage but whether mosaicism is no issue at all at the blastocyst stage is currently called into question.

STUDY DESIGN, SAMPLES/MATERIALS, METHODS

A questionnaire was developed on the three major aspects of PGS 2.0: the Why, with general questions such as PGS 2.0 indications; the How, specifically on genetic analysis methods; the When, on the ideal method and timing of embryo biopsy. Thirty-five colleagues have been selected to address these questions on the basis of their experience with PGS, and demonstrated by peer-reviewed publications, presentations at meetings and participation in the discussion. The first group of experts who were asked about 'The Why' comprised fertility experts, the second group of molecular biologists were asked about 'The How' and the third group of embryologists were asked about 'The When'. Furthermore, the geographical distribution of the experts has been taken into account. Thirty have filled in the questionnaire as well as actively participated in the redaction of the current paper.

MAIN RESULTS AND THE ROLE OF CHANCE

The 30 participants were from Europe (Belgium, Germany, Greece, Italy, Netherlands, Spain, UK) and the USA. Array comparative genome hybridization is the most widely used method amongst the participants, but it is slowly being replaced by massive parallel sequencing. Most participants offering PGS 2.0 to their patients prefer blastocyst biopsy. The high efficiency of vitrification of blastocysts has added a layer of complexity to the discussion, and it is not clear whether PGS in combination with vitrification, PGS alone, or vitrification alone, followed by serial thawing and eSET will be the favoured approach. The opinions range from in favour of the introduction of PGS 2.0 for all IVF patients, over the proposal to use PGS as a tool to rank embryos according to their implantation potential, to scepticism towards PGS pending a positive outcome of robust, reliable and large-scale RCTs in distinct patient groups.

LIMITATIONS, REASONS FOR CAUTION

Care was taken to obtain a wide spectrum of views from carefully chosen experts. However, not all invited experts agreed to participate, which explains a lack of geographical coverage in some areas, for example China. This paper is a collation of current practices and opinions, and it was outside the scope of this study to bring a scientific, once-and-for-all solution to the ongoing debate.

WIDER IMPLICATIONS OF THE FINDINGS

This paper is unique in that it brings together opinions on PGS 2.0 from all different perspectives and gives an overview of currently applied technologies as well as potential future developments. It will be a useful reference for fertility specialists with an expertise outside reproductive genetics.

LARGE SCALE DATA

none.

STUDY FUNDING AND COMPETING INTERESTS

No specific funding was obtained to conduct this questionnaire.

Best practices of ASRM and ESHRE: a journey through reproductive medicine

BACKGROUND

The American Society for Reproductive Medicine (ASRM) and the European Society of Human Reproduction and Embryology (ESHRE) are the two largest societies in the world whose members comprise the major experts and professionals working in the field of reproductive medicine and embryology. These societies have never before had a joint scientific meeting.

METHOD(S)

A 3-day meeting was planned and took place in March of 2012. The goal was to present and debate key topics, as well as modes of practice in reproductive medicine and to discuss recent developments in the field.

RESULT(S)

Presentations by members of ASRM and ESHRE were of three types: 'state of the art' lectures, 'back-to-back' presentations of two points of view and debates.

CONCLUSION(S)

For the first time, ASRM and ESHRE held a joint meeting where a special emphasis was given to presentations on the hottest topics in the field. Although different opinions and approaches sometimes exist on the two sides of the Atlantic, an appreciation and acceptance of these differences was evident, and there was more commonality than divergence of opinion.

Best practices of ASRM and ESHRE: a journey through reproductive medicine

BACKGROUND

The American Society for Reproductive Medicine (ASRM) and the European Society of Human Reproduction and Embryology (ESHRE) are the two largest societies in the world whose members comprise the major experts and professionals working in the field of reproductive medicine and embryology. These societies have never before had a joint scientific meeting.

METHODS

A 3-day meeting was planned and took place in March of 2012. The goal was to present and debate key topics, as well as modes of practice in reproductive medicine and to discuss recent developments in the field.

RESULTS

Presentations by members of ASRM and ESHRE were of three types: 'state of the art' lectures, 'back-to-back' presentations of two points of view and debates.

CONCLUSIONS

For the first time, ASRM and ESHRE held a joint meeting where a special emphasis was given to presentations on the hottest topics in the field. Although different opinions and approaches sometimes exist on the two sides of the Atlantic, an appreciation and acceptance of these differences was evident, and there was more commonality than divergence of opinion.

Five chromosome segregation in polar bodies and the corresponding oocyte

For a comprehensive picture of the meiotic process and to follow up its products, five chromosomes were tested by fluorescent in-situ hybridization in both polar bodies (PB) and corresponding 145 oocytes. Results were obtained in 143 sets and the prediction of euploidy or aneuploidy based on PB analysis was confirmed by direct analysis in 140 oocytes (98%). Concordance for all chromosomes was found in 132 oocytes, while in the remaining eight, at least one chromosome did not reflect the prediction made by the corresponding PB. When restricting the analysis to the 132 fully concordant oocytes, 215 errors were found in PB: 58% in PB1 and 42% in PB2. Premature separation of chromatids occurred in 89% of aneuploid PB1, whereas only 11% of errors derived from bivalent non-disjunction. In 19% of meiosis-I errors, a complementary error in meiosis II compensated the error originated in the first meiotic division. In conclusion, the testing of PB predicted reliably the oocyte’s chromosome condition. Although limited to five chromosomes, the follow up of meiosis by fluorescent in-situ hybridization provided a full description of chromosome allocation during the two divisions characterizing the nuclear maturation of the oocyte.

Polar body array CGH for prediction of the status of the corresponding oocyte. Part I: clinical results

BACKGROUND

Several randomized controlled trials have not shown a benefit from preimplantation genetic screening (PGS) biopsy of cleavage-stage embryos and assessment of up to 10 chromosomes for aneuploidy. Therefore, a proof-of-principle study was planned to determine the reliability of alternative form of PGS, i.e. PGS by polar body (PB) biopsy, with whole genome amplification and microarray-based comparative genomic hybridization (array CGH) analysis.

METHODS

In two centres, all mature metaphase II oocytes from patients who consented to the study were fertilized by ICSI. The first and second PBs (PB1and PB2) were biopsied and analysed separately for chromosome copy number by array CGH. If either or both of the PBs were found to be aneuploid, the corresponding zygote was then also processed by array CGH for concordance analysis.

RESULTS

Both PBs were biopsied from a total of 226 zygotes from 42 cycles (average 5.5 per cycle; range 1-15) in 41 couples with an average maternal age of 40.0 years. Of these, the ploidy status of the zygote could be predicted in 195 (86%): 55 were euploid (28%) and 140 were aneuploid (72%). With only one exception, there was at least one predicted aneuploid zygote in each cycle and in 19 out of 42 cycles (45%), all zygotes were predicted to be aneuploid. Fresh embryos were transferred in the remaining 23 cycles (55%), and one frozen transfer was done. Eight patients had a clinical pregnancy of which seven were evolutive (ongoing pregnancy rates: 17% per cycle and 30% per transfer). The ploidy status of 156 zygotes was successfully analysed by array CGH: 38 (24%) were euploid and 118 (76%) were aneuploid. In 138 cases complete information was available on both PBs and the corresponding zygotes. In 130 (94%), the ploidy status of the zygote was concordant with the ploidy status of the PBs and in 8 (6%), the results were discordant.

CONCLUSIONS

This proof-of-principle study indicates that the ploidy of the zygote can be predicted with acceptable accuracy by array CGH analysis of both PBs.

Polar body array CGH for prediction of the status of the corresponding oocyte. Part II: technical aspects

BACKGROUND

The purpose of this study was to assess the technical aspects related to polar body (PB) biopsy, which might have an influence on the results of the microarray comparative genomic hybridization analysis. Furthermore, a comparison was made between two biopsy methods (mechanical and laser).

METHODS

Biopsy of the first and second PB (PB1 and PB2) was performed by mechanical- or laser-assisted biopsy in two different IVF centres. PBs were separately amplified by whole genome amplification.

RESULTS

The method of biopsy, mechanical or laser had no influence on the proportion of successfully biopsied oocytes. Especially, for the PB2, the timing of biopsy after ICSI was directly correlated to amplification efficiency.

CONCLUSIONS

Special care has to be taken with respect to the timing of biopsy of the PB2. Mechanical- and laser-assisted biopsy give the same performance in terms of diagnostic efficiency.

MLL2 mutation spectrum in 45 patients with Kabuki syndrome

Kabuki Syndrome (KS) is a rare syndrome characterized by intellectual disability and multiple congenital abnormalities, in particular a distinct dysmorphic facial appearance. KS is caused by mutations in the MLL2 gene, encoding an H3K4 histone methyl transferase which acts as an epigenetic transcriptional activator during growth and development. Direct sequencing of all 54 exons of the MLL2 gene in 45 clinically well-defined KS patients identified 34 (75.6%) different mutations. One mutation has been described previously, all others are novel. Clinically, all KS patients were sporadic, and mutations were de novo for all 27 families for which both parents were available. We detected nonsense (n=11), frameshift (n=17), splice site (n=4) and missense (n=2) mutations, predicting a high frequency of absent or non-functional MLL2 protein. Interestingly, both missense mutations located in the C-terminal conserved functional domains of the protein. Phenotypically our study indicated a statistically significant difference in the presence of a distinct facial appearance (p=0.0143) and growth retardation (p=0.0040) when comparing KS patients with an MLL2 mutation compared to patients without a mutation. Our data double the number of MLL2 mutations in KS reported so far and widen the spectrum of MLL2 mutations and disease mechanisms in KS.

What next for preimplantation genetic screening? A polar body approach!

Screening of human preimplantation embryos for numerical chromosome abnormalities has been conducted mostly at the preimplantation stage using fluorescence in situ hybridization. However, it is clear that preimplantation genetic screening (PGS) as it is currently practiced does not improve live birth rates. Therefore the ESHRE PGS Task Force has decided to start a proof of principle study with the aim of determining whether biopsy of the first and second polar body followed by subsequent analysis of the complete chromosome complement of these polar bodies using an array based technique enables a timely identification of the chromosomal status of an oocyte. If the principle of this approach can be proven, it is obvious that a multicentre randomized controlled trial should then be started to determine the clinical value of this technique. In this way the ESHRE PGS Task Force hopes to redirect preimplantation screening from the blind alley to the main road of assisted reproduction.

Validation of preimplantation genetic diagnosis by PCR analysis: genotype comparison of the blastomere and corresponding embryo, implications for clinical practice

The aim of this study was to validate the overall preimplantation genetic diagnosis (PGD)-PCR procedure and to determine the diagnostic value. Genotyped embryos not selected for embryo transfer (ET) and unsuitable for cryopreservation after PGD were used for confirmatory analysis. The PGD genotyped blastomeres and corresponding embryos were compared, and morphology was scored on Day 4 post fertilization. To establish the validity of the PGD-PCR procedure and the diagnostic value, misdiagnosis rate, false-negative rate and negative predictive value were calculated. Moreover, comparison on the validity was made for the biopsy of one or two blastomeres. For the total embryo group (n = 422), a misdiagnosis rate of 7.1% and a false-negative rate of 3.1% were found. The negative predictive value was 96.1%. Poor morphology Day 4 embryos (Class 1) were over-represented in the embryo group in which the blastomere genotype was not confirmed by the whole embryo genotype. The misdiagnosis rate of Class 1 embryos was 12.5% and the false-negative rate 17.1%. Exclusion of these embryos resulted in a misdiagnosis rate of 6.1%, a false-negative rate of 0.5% and a negative predictive value of 99.3%. The two blastomere biopsies revealed a significant higher positive predictive value, lowering the misdiagnosis rate, whereas the negative predictive value remained the same. In conclusion, the PGD-PCR procedure is a valid diagnostic method to select unaffected embryos for ET. The misdiagnosis and false-negative rates decrease by rejecting Class 1 embryos for ET. The biopsy of a second blastomere improves the positive predictive value, lowering the misdiagnosis rate.

mtDNA point mutations are present at various levels of heteroplasmy in human oocytes

Little is known about the load of mutations and polymorphisms in the mitochondrial DNA (mtDNA) of human oocytes and the possible effect these mutations may have during life. To investigate this, we optimised at the single cell level the recently developed method to screen the entire mtDNA for mainly heteroplasmic mutations by denaturing high performance liquid chromatography analysis. This method is sensitive (approximately 1% heteroplasmy detectable), specific and rapid. The entire mtDNA of 26 oocytes of 13 women was screened by this method. Ten different heteroplasmic mutations, of which only one was located in the D-loop and two were observed twice, were detected in seven oocytes with mutation loads ranging from <5% to 50%. From eight women >1 oocyte was received and in four of them heteroplasmic differences between oocytes of the same woman were observed. In one of these four, two homoplasmic D-loop variants were also detected. Additionally, four oocytes of a single woman were sequenced using the MitoChip (which lacks the D-loop region), but all sequences were identical. It is concluded that heteroplasmic mtDNA mutations are common in oocytes and that, depending on the position and mutation load, they might increase the risk of developing OXPHOS disease early or later in life.

The interface between assisted reproductive technologies and genetics: technical, social, ethical and legal issues

The interface between assisted reproductive technologies (ART) and genetics comprises several sensitive and important issues that affect infertile couples, families with severe genetic diseases, potential children, professionals in ART and genetics, health care, researchers and the society in general. Genetic causes have a considerable involvement in infertility. Genetic conditions may also be transmitted to the offspring and hence create transgenerational infertility or other serious health problems. Several studies also suggest a slightly elevated risk of birth defects in children born following ART. Preimplantation genetic diagnosis (PGD) has become widely practiced throughout the world for various medical indications, but its limits are being debated. The attitudes towards ART and PGD vary substantially within Europe. The purpose of the present paper was to outline a framework for development of guidelines to be issued jointly by European Society of Human Genetics and European Society of Human Reproduction and Embryology for the interface between genetics and ART. Technical, social, ethical and legal issues of ART and genetics will be reviewed.

ESHRE PGD Consortium data collection V: Cycles from January to December 2002 with pregnancy follow-up to October 2003

The fifth report of the ESHRE PGD Consortium is presented (data collection V). For the first time, the cycle data were collected for one calendar year (2002) in the following October, so that data collection was complete for pregnancies and babies. The data were collected using a Filemaker Pro database and divided into referrals, cycles, pregnancies and babies. There are currently 66 active centres registered with the consortium; however, the data presented here were obtained from 43 centres and included 1603 referrals, 2219 cycles, 485 pregnancies and 382 babies born. The cycle data were divided into preimplantation genetic diagnosis (PGD) for inherited disorders (including chromosome abnormalities, sexing for X-linked disease and monogenic disorders), aneuploidy screening (PGS) and the use of PGD for social sexing. Data collection V is compared with the previous cumulative data collection (I-IV), which comprised 4058 PGD/PGS cycles that reached oocyte retrieval.

ESHRE PGD Consortium data collection IV: May–December 2001

The ESHRE PGD Consortium was formed in 1997 to survey the practice of preimplantation genetic diagnosis (PGD). Since then, three reports have been published giving an overview on PGD from an ever-increasing number of centres and reporting on an increasing number of PGD cycles and pregnancies and babies born after PGD. After these initial influential publications, important shortcomings were identified primarily on the method of data collection, i.e. with Excel spreadsheets, and in the timing of the collection (cycles were collected in a different time frame from pregnancies and babies, making the follow-up of cycles very difficult). This is why the Steering Committee has made a major investment in developing and implementing a new database in FileMaker Pro 6. It was also decided that cycles would be collected from one calendar year, as well as the pregnancies and babies ensuing from that particular calendar year. This gave us the opportunity to take a closer look at the data collected earlier, and to attempt to improve their quality. This is a report on the corrected data from the first three data collections (I-III) as well as the result of the last data collection (IV) that was completely carried out using the new database.

DHPLC analysis of potassium ion channel genes in congenital long QT syndrome

Congenital long QT syndrome (LQTS) is electrocardiographically characterized by a prolonged QT interval and polymorphic ventricular arrhythmias (torsade de pointes). As a result of these arrhythmias, patients suffer from recurrent syncopes, seizures, or sudden death as the most dramatic event. Mutations in five genes, encoding cardiac ion channels, have been identified in LQTS. Two potassium-channel genes, KCNQ1 (LQT1) and KCNH2 (LQT2 or HERG), are frequently involved in LQTS. Potassium-channel defects account for approximately 50-60% of LQTS. As patients benefit from preventive medication, early detection of a genetic defect is desired to identify the family members at risk. Speed and sensitivity of mutation detection was improved by applying the denaturing high performance liquid chromatography (DHPLC) technique for analysis of the entire KCNQ1 and KCNH2 genes and the protein encoding part of the KCNE1 and KCNE2 genes. By using this methodology, seven missense mutations in the KCNQ1 gene and nine mutations (four missense, two nonsense, one insertion, and two deletions) in the KCNH2 gene have been identified in a total number of 32 index patients diagnosed with LQTS syndrome. We conclude that this method is suitable for rapid identification of LQT gene defects due to the combination of automation, high throughput, sensitivity, and short time of analysis.

ESHRE preimplantation genetic diagnosis (PGD) consortium: data collection II (May 2000)

In 1997, the ESHRE PGD Consortium was formed as part of the ESHRE Special Interest Group on Reproductive Genetics, in order to undertake a long-term study of the efficacy and clinical outcome of preimplantation genetic diagnosis (PGD). In December 1999, the first PGD Consortium report was published discussing referrals of 323 couples, 392 PGD cycles and 82 pregnancies and 79 children born. In the second round of data collection, contributing centres were asked to send in data from their PGD activities before January 1997, as well as from 1st October 1998 until 1st May 2000, in order to have as complete as possible an overview of PGD practices in these centres. A further 563 referrals were sent in as well as 926 PGD cycles, and data on 89 pregnancies (including seven pregnancies ongoing from the previous group) and 83 children were collected. This has led to a considerable amount of cumulative data being acquired: over a period of 7 years (the oldest PGD cycle reported dates from 1994), referral data on 886 couples, cycle data on 1318 PGD cycles and data on 163 pregnancies and 162 babies were collected. In all, these data are encouraging: they show first, that the practice of PGD is becoming more and more established, and an increasing number of different applications is emerging; and second, that collecting these data is worthwhile, as they will be a valuable source of information for all those involved, e.g. in counselling patients and interacting with governmental bodies.

ESHRE Preimplantation Genetic Diagnosis (PGD) Consortium: preliminary assessment of data from January 1997 to September 1998. ESHRE PGD Consortium Steering Committee

The first clinical application of preimplantation genetic diagnosis (PGD) was reported almost a decade ago. Since then, the range of genetic defects that can be detected at single cell level has increased dramatically. At the 13th Annual Meeting of ESHRE in Edinburgh in 1997, a PGD Consortium was formed to undertake the first systematic and long-term study of the efficacy and clinical outcome of PGD. We report here the first data collection covering the period of January 1997 to September 1998. Referral data on 323 couples have been collected for a variety of monogenic and chromosomal disorders, providing information about which patients, at risk for which genetic diseases, are interested in PGD. Data were collected on 392 PGD cycles, resulting in 302 embryo transfers and 66 clinical pregnancies. Because of the importance of follow-up of the children born after PGD, participating centres were asked to contribute data on the pregnancies achieved and the children born after PGD since the start of their PGD programme. Data on 82 pregnancies and 110 fetal sacs were collected, and information was available on 79 children. Finally, biopsy, fluorescence in-situ hybridization and polymerase chain reaction protocols were collected, clearly showing that no consensus exists on technical aspects such as which culture medium to use, and emphasizing the role the PGD Consortium could play in setting up guidelines for good laboratory practice. In conclusion, it is clear that the effort of gathering data on PGD cycles is worthwhile and will be continued in the future, preferably using electronic data collection.

A retrospective follow-up study on intracytoplasmic sperm injection

PURPOSE

Genetic aspects of male subfertility and the novelty of intracytoplasmic sperm injection (ICSI) as a new technique can influence the development of zygotes and children born after ICSI. Therefore, we evaluated the outcome of ICSI compared to in vitro fertilization (IVF).

METHODS

Data from medical records of 233 total pregnancies and the follow-up of 132 children born after IVF and 120 after ICSI were retrospectively analyzed.

RESULTS

No differences were found between ICSI and IVF for early embryonic development and obstetric outcome. In both groups the rate of women undergoing prenatal chromosomal diagnosis was low, 30.0%. The congenital malformation rate was 3.0% after IVF and 1.7% after ICSI, which was not significantly different. Follow-up on development of children born after IVF and ICSI also showed no significant differences.

CONCLUSIONS

Our results indicate that at this moment ICSI is a safe procedure. However, a consistent prospective follow-up is still mandatory to exclude possible risks.

Uniparental maternal disomy 6 in a renal transplant patient

HLA analysis of the family of a renal transplant patient revealed an extremely rare condition. On repeated typings the only demonstrable HLA antigens shown in the propositus were from the maternal haplotype, HLA-A11,-B46,-CW1,-DR14,-DQ1. No paternal antigens could be demonstrated either by serologic or by DNA-typing methods. A paternity investigation was carried out to exclude the possibility of the legal father not being the biological father. The results of this investigation showed a paternity index I = > 20000 and a fatherhood probability W = > 99.995%. Karyotyping of the patient showed two normal chromosomes 6 and no other chromosomal abnormalities. Maternal isodisomy was demonstrated from the analysis of polymorphic DNA markers, involving the short as well as the long arm of chromosome 6. These data are consistent with this patient having the first uniparental maternal disomy 6 reported (inheritance of two identical chromosome 6 haplotypes from the mother and none from the father).

Fluorescence in situ hybridization on paraffin-embedded abortion material as a means of retrospective chromosome analysis

A fluorescence in situ hybridization (FISH) procedure was used to detect chromosome abnormalities in archival abortion material. Nuclei were isolated from 50-microns-thick tissue blocks from 18 selected and karyotyped abortions. Five probes for repetitive centromeric sequences of chromosomes 1, 16, 18, X and Y were used. For each chromosome, at least 200 nuclei were scored blindly, i.e. without knowledge of the karyotype. The FISH results obtained were compatible with the cytogenetic data in 14 cases. There were four discrepancies. Two of these were observed for cases karyotyped as trisomy 16. Furthermore, FISH results showed trisomy 18 in two cases having normal chromosomes 18 and 18q+, respectively. The latter case was not discrepant if the structural rearrangement involved chromosome 18 material. The remaining discrepancies could be explained by chromosomal mosaicism. Admixture of normal maternal cells was also noted. It is concluded that FISH can be used to study retrospectively the presence of chromosome abnormalities in abortion material. However, the quality obtained after the use of fresh material is superior.

Heterogeneity in bladder cancer as detected by conventional chromosome analysis and interphase cytogenetics

Thirty transitional cell carcinomas (TCCs) of the bladder were examined by classical chromosome counting to establish range, modal number, and percentage of metaphases with 2n, 3n, 4n, and > or = 5n chromosomes. In addition, fluorescence in situ hybridization (FISH) was applied to interphase nuclei to detect the percentage of tumor cells showing polyploidization and chromosome imbalance. In FISH, centromere-specific DNA probes for chromosomes 1, 7, 9, and 11 were used. The tumors were analyzed flow cytometrically to determine the DNA index (DI). Fourteen of 21 cases (67%) having a DI = 1 showed, after classical chromosome counting, in addition to a diploid model number, some cells with a 3n and 4n chromosome count. With FISH, eight cases (38%) showed a low percentage of cells with multiple signals for each of the probes, thus indicating polyploidization. In 13 (62%) cases, an imbalance between different chromosomes was detected. In nine tumors having a DI of 1.6 to 1.9, classical chromosome counting showed low percentages of > or = 5n cells in four cases, in addition to a triploid modal number. With FISH in six cases, a low percentage of cells showed five or more signals for each of the chromosomes, indicating polyploidization. In all cases, a chromosome imbalance was detected. With classical chromosome counting not all tumors can be analyzed. With FISH, small percentages of polyploid cells are not recognized. Both methods complement each other in that chromosome counting allows readier detection of heterogeneity in DNA-diploid tumors after polyploidization, whereas FISH allows efficient recognition of the chromosomes involved in the process of imbalance.

Severe mental retardation in a patient with tricho-rhino-phalangeal syndrome type I and 8q deletion

We report a 19-year-old boy with an interstitial deletion of the long arm of chromosome 8 (46, XY, del(8)(pter----q23.3: :q24.13----qter)). He shows the typical clinical symptoms of tricho-rhino-phalangeal syndrome (TRPI) and severe mental retardation, however without multiple exostoses. This is the second report of a combination of abnormalities and interstitial deletion of 8q.

Chromosomal analysis of bladder cancer. III. Nonrandom alterations

Chromosome analysis using G- and C-banding was performed on 13 primary transitional cell carcinomas of the bladder. The chromosome preparations were obtained by a direct method. In eight tumors with a (near) diploid modal chromosome number, the most frequently observed chromosome aberrations were: (partial) monosomy 9 in four cases, deletion of 10q in two cases, and partial trisomy 1 in two cases. In five tumors with a modal chromosome number in the triploid or tetraploid range the chromosomes #1, #3, #7, #9, #11, and #17 were numerically and or structurally abnormal in at least four cases. In three out of ten males, the Y chromosome was missing. These findings suggest that the loss of chromosome #9, and possibly also loss of 10q is a primary event in the karyotypic evolution of transitional cell carcinoma of the bladder.

Chromosomal analysis of bladder cancer. II. A practical method

Twenty-seven successive bladder cancer tissue specimens, varying from noninfiltrating to deeply infiltrating ones, were chromosomally analyzed using a new direct method. Recognizable metaphases were obtained from 25 specimens (93%). In nearly all cases, suitable C-banding and in nine cases G-banding was achieved. Essential steps in this method are colcemid application in two steps, interrupted by washing with Hanks' balanced sodium solution and two separated hypotonic treatments. This method is easy to use and not time consuming.

Chromosomal analysis of bladder cancer: technical aspects

Of 77 patients with bladder carcinoma, 99 tissue specimens--including tissues of patients with recurrent tumors taken after radiotherapy or cytostatics--were subjected to chromosomal analysis. In 42 specimens, recognizable metaphases could be obtained after conventional Giemsa staining and in a smaller number after C- and/or G-banding. All except one had abnormalities of the chromosomes. Short-term cultures for 24-48 hr in RPMI 1640 plus 15% fetal calf serum plus penicillin-streptomycin gave better results than a direct technique (30 min in 0.075 M KCl + 0.1 microgram colcemid/ml at 37 degrees C, followed by fixation). In low stage/grade tumors the number of recognizable metaphases obtained after short-term cultures is lower than in higher stage/grade tissue specimens.