Another case of imprinting defect in a girl with Angelman syndrome who was conceived by intracytoplasmic semen injection

A systematic review of genome-wide analyses of methylation changes associated with assisted reproductive technologies in various tissues

IMPORTANCE

Because analytic technologies improve, increasing amounts of data on methylation differences between assisted reproductive technology (ART) and unassisted conceptions are available. However, various studies use different tissue types and different populations in their analyses, making data comparison and integration difficult.

OBJECTIVE

To compare and integrate data on genome-wide analyses of methylation differences due to ART, allowing exposure of overarching themes.

EVIDENCE REVIEW

All studies undertaking genome-wide analysis of human methylation differences due to ART or infertility in any tissue type across the lifespan were assessed for inclusion.

FINDINGS

Seventeen studies were identified that met the inclusion criteria. One study assessed trophectoderm biopsies, 2 first-trimester placenta, 1 first-trimester fetal tissue, 2 term placenta, 7 cord blood, 3 newborn dried blood spots, 1 childhood buccal smears, 1 childhood peripheral blood, and 2 adult peripheral blood. Eleven studies compared tissues from in vitro fertilization (IVF) conceptions with those of unassisted conceptions, 4 compared intracytoplasmic sperm injection with unassisted conceptions, 4 compared non-IVF fertility treatment (NIFT) with unassisted conceptions, 4 compared NIFT with IVF, and 5 compared an infertile population (conceiving via various methods) with an unassisted presumably fertile population. In studies assessing placental tissue, 1 gene with potential methylation changes due to IVF when compared with unassisted conceptions was identified by 2 studies. In blood, 11 potential genes with methylation changes due to IVF compared with unassisted conceptions were identified by 2 studies, 1 of which was identified by 3 studies. Three potentially affected genes were identified by 2 studies involving blood between intracytoplasmic sperm injection and unassisted populations. There were no overlapping genes identified in any tissue type between NIFT and unassisted populations, between NIFT and IVF, or the infertility combined population when compared with the unassisted fertile population.

CONCLUSIONS

Comparing studies is challenging due to differing variables between analyses. However, even in similar tissue types and populations, overlapping methylation changes are limited, suggesting that differences due to ART are minimal.

RELEVANCE

Information from this systematic review is significant for providers and patients who provide and use ART to understand methylation risks that may be associated with the technology.

Infertility and treatments used have minimal effects on first-trimester placental DNA methylation and gene expression

OBJECTIVE

To determine whether deoxyribonucleic acid (DNA) methylation alterations exist in the first-trimester human placenta between conceptions using fertility treatments and those that do not and, if so, whether they are the result of underlying infertility or fertility treatments. We also assessed whether significant alterations led to changes in gene expression.

DESIGN

We compared DNA methylation of the first-trimester placenta from singleton pregnancies that resulted in live births from unassisted, in vitro fertilization (IVF), and non-IVF fertility treatment (NIFT) conceptions using the Infinium MethylationEPIC BeadChip array. Significant CpG sites were compared with corresponding ribonucleic acid sequencing analysis in similar cohorts to determine whether methylation alterations lead to differences in gene expression.

SETTING

Academic medical center.

PATIENT(S)

A total of 138 singleton pregnancies undergoing chorionic villus sampling resulting in a live birth were recruited for methylation analysis (56 unassisted, 38 NIFT, and 44 IVF conceptions). Ribonucleic acid-sequencing data consisted of 141 subjects (74 unassisted, 33 NIFT, and 34 IVF conceptions) of which 116 overlapped with the methylation cohort.

INTERVENTION(S)

In vitro fertilization-conceived pregnancy or pregnancy conceived via NIFT, such as ovulation induction and intrauterine insemination.

MAIN OUTCOME MEASURE(S)

Significant methylation changes at CpG sites after adjustment for multiple comparisons. The secondary outcome was gene expression changes of significant CpG sites.

RESULT(S)

Of the 741,145 probes analyzed in the placenta, few were significant at Bonferroni <0.05: 185 CpG sites (0.025%) significant in pregnancies conceived with the fertility treatments (NIFT + IVF) vs. unassisted conceptions; 28 in NIFT vs. unassisted; 195 in IVF vs. unassisted; and only 13 (0.0018%) in IVF vs. NIFT conceptions. Of all significant CpG sites combined, 10% (35) were located in genes with suggestive gene expression changes, but none were significant after adjustment for multiple comparisons (ribonucleic acid sequencing false discovery rate <0.05). None of the 13 differentially methylated probes in the IVF vs. NIFT placenta were located in genes with suggestive IVF vs. NIFT gene expression differences.

CONCLUSION(S)

Underlying infertility is the most significant contributor to the minimal differences in first-trimester placental methylation, and not the specific fertility treatment used, such as IVF.

Risk of genetic and epigenetic alteration in children conceived following ART: Is it time to return to nature whenever possible?

Assisted reproductive technology may influence epigenetic signature as the procedures coincide with the extensive epigenetic modification occurring from fertilization to embryo implantation. However, it is still unclear to what extent ART alters the embryo epigenome. In vivo fertilization occurs in the fallopian tube, where a specific and natural environment enables the embryo's healthy development. During this dynamic period, major waves of epigenetic reprogramming, crucial for the normal fate of the embryo, take place. Over the past decade, concerns relating to the raised incidence of epigenetic anomalies and imprinting following ART have been raised by several authors. Epigenetic reprogramming is particularly susceptible to environmental conditions during the periconceptional period; therefore, unphysiological conditions, including ovarian stimulation, in vitro fertilization, embryo culture, cryopreservation of gametes and embryos, parental lifestyle, and underlying infertility, have the potential to contribute to epigenetic dysregulation independently or collectively. This review critically appraises the evidence relating to the association between ART and genetic and epigenetic modifications that may be transmitted to the offspring.

Blastocyst culture of non-top-quality cleavage embryos may increase the risk of anembryonic pregnancy following in vitro fertilization: a retrospective cohort study

Background

Anembryonic pregnancy (AP) is the most severe dysmorphogenesis of human embryo development and a frequent presentation of early pregnancy loss (EPL). Studies have analyzed the association between assisted reproductive technologies (ART) and EPL. However, the specific relationship between ART and AP has not been fully elucidated. Several studies suggested that non-genomic anomalies might be related to AP and ART might increase the risk of epigenetic changes, thus possibly detecting some associations between ART and AP. Our study aims to find out any possible risk factors of AP in ART treatments, and translate the results into clinical practice.

Methods

A retrospective cohort study was conducted in Nanfang Hospital. Data from 1,765 singleton pregnancies following fresh or frozen-thawed embryo transfer from January 2014 to December 2017 were collated with the inclusion of EPLs and normal live births (NLB). Participants were divided into three groups: NLB (full-term birth with normal body weight infants), EPL (spontaneous pregnancy loss prior to 13 weeks gestation) with embryos (EE), and APs (embryonic pole was invisible in two consecutive ultrasound examinations). The basic characteristics of the patients and the association between ART-related variables and AP were analyzed using one-way analysis of variance (ANOVA) and multivariable logistic regression model, respectively. Products of conception (POC) from AP and EE patients received karyotype analysis using multiplex ligation-dependent probe amplification (MLPA).

Results

Blastocyst culture of non-top-quality cleavage stage embryos almost doubled the percentage of AP in EPL (45.9% vs. 24.4%, P=0.037), and the normal euploid rate was significantly higher in the AP group (50.5% vs. 32.3%, P=0.003). Using multivariable logistic regression model, we found that blastocyst transfer and advanced maternal age might be risk factors for AP (OR >1, P<0.05). Deceased β-HCG level might indicate its occurrence (OR <1, P<0.001) while CoQ10 supplementation might be a protective factor (OR <1, P<0.001).

Conclusions

The occurrence of AP may be due to epigenetic abnormalities associated with advanced maternal age and extended in vitro embryo culture, while CoQ10 supplementation may be a potential method in preventing AP. Future multi-center prospective cohort studies should be conducted to verify these results.

From first report to clinical trials: a bibliometric overview and visualization of the development of Angelman syndrome research

Angelman syndrome is a rare neurodevelopmental disorder caused by mutations affecting the chromosomal 15q11-13 region, either by contiguous gene deletions, imprinting defects, uniparental disomy, or mutations in the UBE3A gene itself. Phenotypic abnormalities are driven primarily, but not exclusively (especially in 15q11-13 deletion cases) by loss of expression of the maternally inherited UBE3A gene expression. The disorder was first described in 1965 by the English pediatrician Harry Angelman. Since that first description of three children with Angelman syndrome, there has been extensive research into the genetic, molecular and phenotypic aspects of the disorder. In the last decade, this has resulted in over 100 publications per year. Collectively, this research has led the field to a pivotal point in which restoring UBE3A function by genetic therapies is currently explored in several clinical trials. In this study, we employed a bibliometric approach to review and visualize the development of Angelman syndrome research over the last 50 years. We look into different parameters shaping the progress of the Angelman syndrome research field, including source of funding, publishing journals and international collaborations between research groups. Using a network approach, we map the focus of the research field and how that shifted over time. This overview helps understand the shift of research focus in the field and can provide a comprehensive handbook of Angelman syndrome research development.

Is there any effect on imprinted genes H19, PEG3, and SNRPN during AOA?

Assisted oocyte activation (AOA) has been proposed as an effective technique to overcome the problem of impaired fertilization after intracytoplasmic sperm injection (ICSI) but the safety of AOA remains a concern. We aimed to investigate if AOA induces imprinting effects on embryos. We used 13 cleavage embryos, nine blastocysts, and eight placentas from 15 patients. The subjects were divided into six groups by tissue type and with or without AOA. The methylation levels of imprinted genes (H19, paternally expressed gene [PEG3] and small nuclear ribonucleoprotein polypeptide N [SNRPN]) were tested by pyrosequencing. We observed different methylation levels among cleavage embryos. The variability was much more remarkable between cleavage embryos than blastocysts and placenta tissues. The methylation levels were especially higher in SNRPN and lower in the H19 gene in AOA embryos than those without AOA. No significant difference was found either among blastocysts or among placenta tissues regardless of AOA. The methylation levels of the three genes in blastocysts were very similar to those in the placenta. Compared to conventional ICSI, AOA changed imprinting methylation rates at H19 and SNRPN in cleavage embryos but not in the blastocyst stage and placenta. We recommend that blastocyst transfer should be considered for patients undergoing AOA during in vitro fertilization.

Oxygen concentration affects de novo DNA methylation and transcription in in vitro cultured oocytes

BACKGROUND

Reproductive biology methods rely on in vitro follicle cultures from mature follicles obtained by hormonal stimulation for generating metaphase II oocytes to be fertilised and developed into a healthy embryo. Such techniques are used routinely in both rodent and human species. DNA methylation is a dynamic process that plays a role in epigenetic regulation of gametogenesis and development. In mammalian oocytes, DNA methylation establishment regulates gene expression in the embryos. This regulation is particularly important for a class of genes, imprinted genes, whose expression patterns are crucial for the next generation. The aim of this work was to establish an in vitro culture system for immature mouse oocytes that will allow manipulation of specific factors for a deeper analysis of regulatory mechanisms for establishing transcription regulation-associated methylation patterns.

RESULTS

An in vitro culture system was developed from immature mouse oocytes that were grown to germinal vesicles (GV) under two different conditions: normoxia (20% oxygen, 20% O₂) and hypoxia (5% oxygen, 5% O₂). The cultured oocytes were sorted based on their sizes. Reduced representative bisulphite sequencing (RRBS) and RNA-seq libraries were generated from cultured and compared to in vivo-grown oocytes. In the in vitro cultured oocytes, global and CpG-island (CGI) methylation increased gradually along with oocyte growth, and methylation of the imprinted genes was similar to in vivo-grown oocytes. Transcriptomes of the oocytes grown in normoxia revealed chromatin reorganisation and enriched expression of female reproductive genes, whereas in the 5% O₂ condition, transcripts were biased towards cellular stress responses. To further confirm the results, we developed a functional assay based on our model for characterising oocyte methylation using drugs that reduce methylation and transcription. When histone methylation and transcription processes were reduced, DNA methylation at CGIs from gene bodies of grown oocytes presented a lower methylation profile.

CONCLUSIONS

Our observations reveal changes in DNA methylation and transcripts between oocytes cultured in vitro with different oxygen concentrations and in vivo-grown murine oocytes. Oocytes grown under 20% O₂ had a higher correlation with in vivo oocytes for DNA methylation and transcription demonstrating that higher oxygen concentration is beneficial for the oocyte maturation in ex vivo culture condition. Our results shed light on epigenetic mechanisms for the development of oocytes from an immature to GV oocyte in an in vitro culture model.

Risk of cancer in children and young adults conceived by assisted reproductive technology

STUDY QUESTION

Do children conceived by ART have an increased risk of cancer?

SUMMARY ANSWER

Overall, ART-conceived children do not appear to have an increased risk of cancer.

WHAT IS KNOWN ALREADY

Despite the increasing use of ART, i.e. IVF or ICSI worldwide, information about possible long-term health risks for children conceived by these techniques is scarce.

STUDY DESIGN, SIZE, DURATION

A nationwide historical cohort study with prospective follow-up (median 21 years), including all live-born offspring from women treated with subfertility treatments between 1980 and 2001.

PARTICIPANTS/MATERIALS, SETTING, METHODS

All offspring of a nationwide cohort of subfertile women (OMEGA study) treated in one of the 12 Dutch IVF clinics or two fertility clinics. Of 47 690 live-born children, 24 269 were ART-conceived, 13 761 naturally conceived and 9660 were conceived naturally or through fertility drugs, but not by ART. Information on the conception method of each child and potential confounders were collected through the mothers’ questionnaires and medical records. Cancer incidence was ascertained through linkage with The Netherlands Cancer Registry from 1 January 1989 until 1 November 2016. Cancer risk in ART-conceived children was compared with risks in naturally conceived children from subfertile women (hazard ratios [HRs]) and with the general population (standardized incidence ratios [SIRs]).

MAIN RESULTS AND THE ROLE OF CHANCE

The median follow-up was 21 years (interquartile range (IQR): 17–25) and was shorter in ART-conceived children (20 years, IQR: 17–23) compared with naturally conceived children (24 years, IQR: 20–30). In total, 231 cancers were observed. Overall cancer risk was not increased in ART-conceived children, neither compared with naturally conceived children from subfertile women (HR: 1.00, 95% CI 0.72–1.38) nor compared with the general population (SIR = 1.11, 95% CI: 0.90–1.36). From 18 years of age onwards, the HR of cancer in ART-conceived versus naturally conceived individuals was 1.25 (95% CI: 0.73–2.13). Slightly but non-significantly increased risks were observed in children conceived by ICSI or cryopreservation (HR = 1.52, 95% CI: 0.81–2.85; 1.80, 95% CI: 0.65–4.95, respectively). Risks of lymphoblastic leukemia (HR = 2.44, 95% CI: 0.81–7.37) and melanoma (HR = 1.86, 95% CI: 0.66–5.27) were non-significantly increased for ART-conceived compared with naturally conceived children.

LIMITATIONS, REASONS FOR CAUTION

Despite the large size and long follow-up of the cohort, the number of cancers was rather small for subgroup analyses as cancer in children and young adults is rare.

WIDER IMPLICATIONS OF THE FINDINGS

Overall, ART-conceived children do not appear to have an increased cancer risk after a median follow-up of 21 years. This large study provides important results, enabling physicians to better inform couples considering ART about the long-term safety of ART for their children. However, larger studies with prolonged follow-up are needed to investigate cancer risk in adults and in children conceived by ICSI and/or from cryopreserved embryos.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by The Dutch Cancer Society (NKI 2006-3631) which funded the OMEGA-women’s cohort and Children Cancer Free (KIKA;147) which funded the OMEGA-offspring cohort. We declare no competing interests.

Perturbations in imprinted methylation from assisted reproductive technologies but not advanced maternal age in mouse preimplantation embryos

Background

Over the last several decades, the average age of first-time mothers has risen steadily. With increasing maternal age comes a decrease in fertility, which in turn has led to an increase in the use of assisted reproductive technologies by these women. Assisted reproductive technologies (ARTs), including superovulation and embryo culture, have been shown separately to alter imprinted DNA methylation maintenance in blastocysts. However, there has been little investigation on the effects of advanced maternal age, with or without ARTs, on genomic imprinting. We hypothesized that ARTs and advanced maternal age, separately and together, alter imprinted methylation in mouse preimplantation embryos. For this study, we examined imprinted methylation at three genes, Snrpn, Kcnq1ot1, and H19, which in humans are linked to ART-associated methylation errors that lead to imprinting disorders.

Results

Our data showed that imprinted methylation acquisition in oocytes was unaffected by increasing maternal age. Furthermore, imprinted methylation was normally acquired when advanced maternal age was combined with superovulation. Analysis of blastocyst-stage embryos revealed that imprinted methylation maintenance was also not affected by increasing maternal age. In a comparison of ARTs, we observed that the frequency of blastocysts with imprinted methylation loss was similar between the superovulation only and the embryo culture only groups, while the combination of superovulation and embryo culture resulted in a higher frequency of mouse blastocysts with maternal imprinted methylation perturbations than superovulation alone. Finally, the combination of increasing maternal age with ARTs had no additional effect on the frequency of imprinted methylation errors.

Conclusion

Collectively, increasing maternal age with or without superovulation had no effect of imprinted methylation acquisition at Snrpn, Kcnq1ot1, and H19 in oocytes. Furthermore, during preimplantation development, while ARTs generated perturbations in imprinted methylation maintenance in blastocysts, advanced maternal age did not increase the burden of imprinted methylation errors at Snrpn, Kcnq1ot1, and H19 when combined with ARTs. These results provide cautious optimism that advanced maternal age is not a contributing factor to imprinted methylation errors in embryos produced in the clinic. Furthermore, our data on the effects of ARTs strengthen the need to advance clinical methods to reduce imprinted methylation errors in in vitro-produced embryos.

Impact of assisted reproduction, infertility, sex and paternal factors on the placental DNA methylome

Children conceived using Assisted Reproductive Technologies (ART) have a higher incidence of growth and birth defects, attributable in part to epigenetic perturbations. Both ART and germline defects associated with parental infertility could interfere with epigenetic reprogramming events in germ cells or early embryos. Mouse models indicate that the placenta is more susceptible to the induction of epigenetic abnormalities than the embryo, and thus the placental methylome may provide a sensitive indicator of 'at risk' conceptuses. Our goal was to use genome-wide profiling to examine the extent of epigenetic abnormalities in matched placentas from an ART/infertility group and control singleton pregnancies (n = 44/group) from a human prospective longitudinal birth cohort, the Design, Develop, Discover (3D) Study. Principal component analysis revealed a group of ART outliers. The ART outlier group was enriched for females and a subset of placentas showing loss of methylation of several imprinted genes including GNAS, SGCE, KCNQT1OT1 and BLCAP/NNAT. Within the ART group, placentas from pregnancies conceived with in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) showed distinct epigenetic profiles as compared to those conceived with less invasive procedures (ovulation induction, intrauterine insemination). Male factor infertility and paternal age further differentiated the IVF/ICSI group, suggesting an interaction of infertility and techniques in perturbing the placental epigenome. Together, the results suggest that the human placenta is sensitive to the induction of epigenetic defects by ART and/or infertility, and we stress the importance of considering both sex and paternal factors and that some but not all ART conceptuses will be susceptible.

Epigenetics, Assisted Reproduction, and Intracytoplasmic Sperm Injection: A Review of the Current Data

Since the birth of the first in vitro fertilisation baby in 1978, >5 million babies have been born worldwide using assisted reproductive technologies (ART). ART were initially considered safe, but, in recent years, concerns regarding the association between these procedures and the increasing incidence of imprinting diseases have developed. There are numerous steps involved in ART and there are many variables that must be considered; even parental infertility may play an important role in offspring epigenetic modifications. This review presents available data from the literature regarding the incidence of these epigenetic modifications after ART, with a primary focus on oocyte insemination methodology. The authors conclude that ART, especially intracytoplasmic sperm injection, may induce epigenetic changes that can be transmitted to the offspring, but additional data are necessary to evaluate the factors involved and to determine the safety of each ART step.

Ambient air pollution, H19/DMR methylation in cord blood and newborn size: A pilot study in Zhengzhou City, China

Prenatal exposure to air pollutants is believed to be associated with adverse birth outcomes. However, the potential mechanisms, especially the epigenetic modified effects, still remain unclear. This study was designed to explore the association of air pollution, H19/DMR methylation levels, and birth weight and length. A total of 527 mother-infant pairs were recruited from Houzhai Center Hospital, Zhengzhou. Air pollution data during the study period was collected. The methylation at H19 promoter region and H19 DMR in maternal and cord bloods were determined using real-time PCR analysis. Ridge regression was used to analyze the association of air pollutants exposure during gestation with H19/DMR methylation and birth weight and length respectively. Results showed that prenatal exposure to NO₂ was associated with higher H19 methylation in cord blood. Whereas SO₂ and PM₁₀ exposure were associated with lower H19 and H19 DMR methylation respectively. After stratification by pregnancy trimesters, the association of H19 methylation in cord blood with PM₁₀ exposure also was found. Furthermore, prenatal exposures to air pollutants also were associated with birth weight and length. Specifically, with the increase of maternal SO₂ exposure during the entire pregnancy, birth weight and length significantly decreased. While birth weight and birth length were significantly increased with NO₂ exposure. The stratified analysis also found the associations between PM₁₀ exposure and birth sizes in different trimesters. In conclusion, the gene methylation level in cord blood might be associated with prenatal environmental exposures. Birth weight and length were associated with both prenatal environmental exposures and genetic factors.

The status of global DNA methylation in the spermatozoa of smokers and non-smokers

RESEARCH QUESTION

Does regular smoking affect semen quality and the levels of DNA methylation in mature human spermatozoa?

DESIGN

Spermatozoa from 109 men were evaluated (55 smokers and 54 non-smokers). DNA was extracted from purified spermatozoa, and DNA methylation was quantified by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Global DNA methylation of non-smokers is significantly lower (P < 0.001) than that of smokers (4.85 ± 2.72 and 7.08 ± 1.77 ng/μl, respectively). Moreover, the mean global DNA methylation levels were significantly correlated (r = 0.22;P = 0.02) with non-condensed chromatin in the spermatozoa. Levels of non-condensed chromatin were significantly higher (P < 0.001) in smokers (29.75 ± 9.38%) compared with non-smokers (20.96 ± 11.31%). Furthermore, global sperm DNA methylation was negatively correlated with high significance (P < 0.010) with sperm: count (r = -0.27), motility (r = -0.30) and vitality (r = -0.26).

CONCLUSION

Smoking interferes with DNA methylation. Also, DNA methylation is significantly correlated with sperm parameters and sperm non-condensed chromatin. These data emphasize another detrimental effect of smoking on male fertility. DNA methylation may, therefore, be considered as a fertility marker in men.

Aberrant DNA Methylation of IGF2-H19 Locus in Human Fetus and in Spermatozoa From Assisted Reproductive Technologies

Given the higher risk of developing imprinting disorders in assisted reproductive technology (ART)-conceived children, we hypothesized that ART may affect DNA methylation of the insulin-like growth factor 2 (IGF2), H19, small nuclear ribonucleoprotein polypeptide N (SNRPN) differentially methylated regions (DMRs) at the fetal stage, which in turn may be associated with sperm abnormalities. A total of 4 patient groups were recruited, namely, multifetal reduction following in vitro fertilization (IVF)/ intracytoplasmic sperm injection (ICSI; n = 56), multifetal reduction following controlled ovarian hyperstimulation (COH; n = 42), male patients with normal semen parameters denoted as normozoospermia group (NZ) for IVF (n = 36), and male patients presenting with asthenozoospermia (OAZ) for ICSI (n = 38). The expression levels and the DNA methylation status of IGF2-H19 and SNRPN DMRs in the fetuses and the semen samples were evaluated by real-time quantitative polymerase chain reaction and pyrosequencing. In our results, the expression levels of H19 were significantly higher, whereas the methylation rates were lower in IVF-conceived fetuses compared to the control group (P < .05). Furthermore, higher methylation rates of IGF2 DMR2 and SNRPN DMR were detected both in IVF- and ICSI-conceived fetuses (P < .05). The data further indicated that the patients who presented with the majority of the CpG sites in the H19 DMR region that were lower methylated were those in the OAZ group. The results demonstrated that the epigenetic dysregulations of IGF2-H19 and SNRPN DMRs that were caused by ART were noted in the fetuses. Moreover, the present study suggested that epigenetic perturbations of the H19 DMR might be a key biomarker for spermatogenesis defects in humans.

Do the children born after assisted reproductive technology have an increased risk of birth defects? A systematic review and meta-analysis

Background: Assisted reproductive technologies (ARTs) have made great progress. However, whether tube baby born after ART were at an increased risk of birth defects is not clear.Objective: To assess whether the ART increases the risk of birth defects in children born after ART.Search strategy: Medline, Google Scholar, and the Cochrane Library were searched.Selection criteria: Clinical trials that evaluate the risk of birth defect in children born after in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) and natural conceptions (NC) were included. The primary outcome was the prevalence of birth defects.Data collection and analysis: The relative risk was used as the summary measure with random effects model. We assessed heterogeneity between studies using the I² index.Main results: Totally 46 studies were included. The pooled relative risk (RR) estimated suggested there was an increased risk of birth defects in ART compared with the NC group (RR: 1.40; 95% CI 1.31-1.49). Twenty and fifteen studies were included to compare the risk of birth defects between NC and IVF/ICSI, respectively. The results indicated that both IVF and ICSI increase the risk of birth defects (IVF: RR 1.25; 95% CI 1.12-1.40; ICSI: RR 1.29; 95% CI 1.14-1.45). When subgroup according to plurality, 22 studies assessed the risk of birth defects after ART or NC in singletons and 15 studies evaluated the risk of birth defects in twins. The pooled RRs were 1.41 (95% CI 1.30-1.52) and 1.18 (95% CI 0.98-1.42), respectively.Conclusions: Children born after ART were at an increased risk of birth defects compared with NC. There was no difference in birth defects risk between ART twins and NC twins.

Overrepresentation of pregnancies conceived by artificial reproductive technology in prenatally identified fetuses with Beckwith-Wiedemann syndrome

OBJECTIVES

In vitro fertilization (IVF) has been linked to an increased risk for imprinting disorders in offspring. The data so far have predominantly been retrospective, comparing the rate of IVF conceptions in affected patients with controls. We describe a series of fetuses with omphalocele that were tested for Beckwith-Wiedemann syndrome (BWS) and subsequently ascertained as to whether pregnancies were conceived by assisted reproductive technologies (ART).

METHODS

Fetuses were tested for BWS by Southern blot, PCR based methods, and methylation analysis to identify the imprinting status at primarily the IC2 locus, KCNQ1OT1, as well as IC1, H19/IGF-2. Some fetuses were also tested for uniparental disomy of chromosome 11p.

RESULTS

We tested 301 fetuses with omphalocele for BWS. Forty samples were positive. Sixteen were from IVF pregnancies, for an overall rate of 40%. Such as high proportion of IVF pregnancies in a series of BWS-positive fetuses has not been described previously. Possible factors such as twinning and ascertainment bias are discussed.

CONCLUSION

We found about a 20-fold overrepresentation of IVF cases in fetuses with BWS/omphalocele when compared with the rate of ART pregnancies in the USA (p < .0001). Our series provides support for an association of IVF and BWS. Patients should be counseled about these risks and made aware of the availability of prenatal diagnosis for detection.

Association of assisted reproductive technology and multiple pregnancies with the risks of birth defects and stillbirth: A retrospective cohort study

Assisted reproductive technology (ART) has been widely used among women with infertility. However, the association of ART with birth defects and stillbirth remains controversial and has rarely been reported in China. A retrospective cohort study of 112,043 pregnant women and 114,522 newborns from 2006 to 2016 was performed. Compared to spontaneously conceived infants, ART-conceived infants had a higher likelihood of any birth defect, with an adjusted odds ratio (OR) of 2.10 (95% confidence interval, 1.63–2.69). ART-conceived infants also had a significantly increased risk for subcategories of cardiovascular, musculoskeletal, urogenital, gastrointestinal, and respiratory defects. Most (62.25%) of the effect of ART on birth defects was a direct effect, whereas 37.75% of the effect of ART on birth defects was due to multiple pregnancies (i.e., an indirect effect). Compared with naturally conceived singletons, the combined effect of ART and twins on the risk of birth defects was lower than that of the sum of the individual effects of ART and twins on the risk of birth defects, with an adjusted OR of 0.54 (0.32–0.92). These findings clearly show that ART is associated with an increased risk of birth defects in China and may provide guidance to couples and obstetricians in selecting numbers of pregnancies and in identifying organs at a high risk of birth defects.

Comprehensive meta-analysis reveals association between multiple imprinting disorders and conception by assisted reproductive technology

PURPOSE

To determine whether a history of conception by assisted reproductive technology (ART) is associated with occurrence of one or more imprinting disorders of either maternal or paternal origin.

METHODS

We implemented a systematic review of scholarly literature followed by comprehensive meta-analysis to quantitatively synthesize data from reports relating to use of ART to occurrence of any imprinting disorder of humans, including Beckwith-Wiedemann (BWS), Angelman (AS), Prader-Willi (PWS), and Silver-Russell (SRS) syndromes, as well as transient neonatal diabetes mellitus (TNDB) and sporadic retinoblasoma (RB).

RESULTS

The systematic review identified 13 reports presenting unique data from 23 studies that related conception following ART to occurrence of imprinting disorders. Multiple studies of four disorder were identified, for which meta-analysis yielded the following summary estimates of associations with a history of ART: AS, summary odds ratio (sOR) = 4.7 (95% confidence interval (CI) 2.6-8.5, 4 studies); BWS, sOR = 5.8 (95% CI 3.1-11.1, 8 studies); PWS, sOR = 2.2 (95% CI 1.6-3.0, 6 studies); SRS, sOR = 11.3 (95% CI 4.5-28.5, 3 studies). Only one study reported on each of TNDB and RB.

CONCLUSION

Published data reveal positive associations between history of ART conception and each of four imprinting disorders. Reasons for these associations warrant further investigation.

Expert consensus document: Clinical and molecular diagnosis, screening and management of Beckwith-Wiedemann syndrome: an international consensus statement

Beckwith-Wiedemann syndrome (BWS), a human genomic imprinting disorder, is characterized by phenotypic variability that might include overgrowth, macroglossia, abdominal wall defects, neonatal hypoglycaemia, lateralized overgrowth and predisposition to embryonal tumours. Delineation of the molecular defects within the imprinted 11p15.5 region can predict familial recurrence risks and the risk (and type) of embryonal tumour. Despite recent advances in knowledge, there is marked heterogeneity in clinical diagnostic criteria and care. As detailed in this Consensus Statement, an international consensus group agreed upon 72 recommendations for the clinical and molecular diagnosis and management of BWS, including comprehensive protocols for the molecular investigation, care and treatment of patients from the prenatal period to adulthood. The consensus recommendations apply to patients with Beckwith-Wiedemann spectrum (BWSp), covering classical BWS without a molecular diagnosis and BWS-related phenotypes with an 11p15.5 molecular anomaly. Although the consensus group recommends a tumour surveillance programme targeted by molecular subgroups, surveillance might differ according to the local health-care system (for example, in the United States), and the results of targeted and universal surveillance should be evaluated prospectively. International collaboration, including a prospective audit of the results of implementing these consensus recommendations, is required to expand the evidence base for the design of optimum care pathways.

Impairment of sperm DNA methylation in male infertility: a meta-analytic study

Considering the widespread use of assisted reproductive techniques (ART), DNA methylation of specific genes involved in spermatogenesis achieves increasingly clinical relevance, representing a possible explanation of increased incidence of syndromes related to genomic imprinting in medically assisted pregnancies. Several trials suggested a relationship between male sub-fertility and sperm DNA methylation, although its weight on seminal parameters alteration is still a matter of debate. To evaluate whether aberrant sperm DNA methylation of imprinted genes is associated with impaired sperm parameters. Meta-analysis of controlled clinical trials evaluating imprinted genes sperm DNA methylation comparing men with idiopathic infertility to fertile controls. Twenty-four studies were included, allowing a meta-analytic evaluation for H19, MEST, SNRPN, and LINE-1. When a high heterogeneity of the results was demonstrated, the random effect model was used. H19 methylation levels resulted significantly lower in 879 infertile compared with 562 fertile men (7.53%, 95% CI: 5.14-9.93%, p < 0.001), suggesting a 9.91-fold higher risk ratio to show aberrant sperm DNA methylation (95% CI: 5.55-17.70, p < 0.001, I²  = 19%) in infertile men. The mean MEST methylation level was significantly higher in 846 infertile compared with 353 fertile men (3.35%, 95% CI: 1.41-5.29%, p < 0.001), as well as for SNRPN comparing 301 infertile men with 124 controls (3.23%, 95% CI: 0.75-5.72%, p < 0.001). LINE-1 methylation levels did not differ between 291 infertile men and 198 controls (0.44%, 95% CI: -2.04-1.16%, p = 0.63). The meta-analytic approach demonstrated that male infertility is associated with altered sperm methylation at H19, MEST, and SNRPN. Although its role in infertility remains unclear, sperm DNA methylation could be associated with the epigenetic risk in ART. In this setting, before proposing this analysis in clinical practice, an accurate identification of the most representative genes and a cost-effectiveness evaluation should be assessed in ad hoc prospective studies.

Genetic and epigenetic risks of assisted reproduction

Assisted reproductive technology (ART) is used primarily for infertility treatments to achieve pregnancy and involves procedures such as in vitro fertilization (IVF), intracytoplasmic sperm injection (ICSI), and cryopreservation. Moreover, preimplantation genetic diagnosis (PGD) of ART is used in couples for genetic reasons. In ART treatments, gametes and zygotes are exposed to a series of non-physiological processes and culture media. Although the majority of children born with this treatment are healthy, some concerns remain regarding the safety of this technology. Animal studies and follow-up studies of ART-borne children suggested that ART was associated with an increased incidence of genetic, physical, or developmental abnormalities, although there are also observations that contradict these findings. As IVF, ICSI, frozen-thawed embryo transfer, and PGD manipulate gametes and embryo at a time that is important for reprogramming, they may affect epigenetic stability, leading to gamete/embryo origins of adult diseases. In fact, ART offspring have been reported to have an increased risk of gamete/embryo origins of adult diseases, such as early-onset diabetes, cardiovascular disease, and so on. In this review, we will discuss evidence related to genetic, especially epigenetic, risks of assisted reproduction.

Maintenance of Mest imprinted methylation in blastocyst-stage mouse embryos is less stable than other imprinted loci following superovulation or embryo culture

Assisted reproductive technologies are fertility treatments used by subfertile couples to conceive their biological child. Although generally considered safe, these pregnancies have been linked to genomic imprinting disorders, including Beckwith-Wiedemann and Silver-Russell Syndromes. Silver-Russell Syndrome is a growth disorder characterized by pre- and post-natal growth retardation. The Mest imprinted domain is one candidate region on chromosome 7 implicated in Silver-Russell Syndrome. We have previously shown that maintenance of imprinted methylation was disrupted by superovulation or embryo culture during pre-implantation mouse development. For superovulation, this disruption did not originate in oogenesis as a methylation acquisition defect. However, in comparison to other genes, Mest exhibits late methylation acquisition kinetics, possibly making Mest more vulnerable to perturbation by environmental insult. In this study, we present a comprehensive evaluation of the effects of superovulation and in vitro culture on genomic imprinting at the Mest gene. Superovulation resulted in disruption of imprinted methylation at the maternal Mest allele in blastocysts with an equal frequency of embryos having methylation errors following low or high hormone treatment. This disruption was not due to a failure of imprinted methylation acquisition at Mest in oocytes. For cultured embryos, both the Fast and Slow culture groups experienced a significant loss of maternal Mest methylation compared to in vivo-derived controls. This loss of methylation was independent of development rates in culture. These results indicate that Mest is more susceptible to imprinted methylation maintenance errors compared to other imprinted genes.

The epigenetic effects of assisted reproductive technologies: ethical considerations

The use of assisted reproductive technologies (ART) has increased significantly, allowing many coping with infertility to conceive. However, an emerging body of evidence suggests that ART could carry epigenetic risks for those conceived through the use of these technologies. In accordance with the Developmental Origins of Health and Disease hypothesis, ART could increase the risk of developing late-onset diseases through epigenetic mechanisms, as superovulation, fertilization methods and embryo culture could impair the embryo’s epigenetic reprogramming. Such epigenetic risks raise ethical issues for all stakeholders: prospective parents and children, health professionals and society. This paper focuses on ethical issues raised by the consideration of these risks when using ART. We apply two key ethical principles of North American bioethics (respect for autonomy and non-maleficence) and suggest that an ethical tension may emerge from conflicting duties to promote the reproductive autonomy of prospective parents on one hand, and to minimize risks to prospective children on the other. We argue that this tension is inherent to the entire enterprise of ART and thus cannot be addressed by individual clinicians in individual cases. We also consider the implications of the ‘non-identity problem’ in this context. We call for additional research that would allow a more robust evidence base for policy. We also call upon professional societies to provide clinicians with guidelines and educational resources to facilitate the communication of epigenetic risks associated with ART to patients, taking into consideration the challenges of communicating risk information whose validity is still uncertain.

Differential expression of parental alleles of BRCA1 in human preimplantation embryos

Gene expression from both parental genomes is required for completion of embryogenesis. Differential methylation of each parental genome has been observed in mouse and human preimplantation embryos. It is possible that these differences in methylation affect the level of gene transcripts from each parental genome in early developing embryos. The aim of this study was to investigate if there is a parent-specific pattern of BRCA1 expression in human embryos and to examine if this affects embryo development when the embryo carries a BRCA1 or BRCA2 pathogenic mutation. Differential parental expression of ACTB, SNRPN, H19 and BRCA1 was semi-quantitatively analysed by minisequencing in 95 human preimplantation embryos obtained from 15 couples undergoing preimplantation genetic diagnosis. BRCA1 was shown to be differentially expressed favouring the paternal transcript in early developing embryos. Methylation-specific PCR showed a variable methylation profile of BRCA1 promoter region at different stages of embryonic development. Embryos carrying paternally inherited BRCA1 or 2 pathogenic variants were shown to develop more slowly compared with the embryos with maternally inherited BRCA1 or 2 pathogenic mutations. This study suggests that differential demethylation of the parental genomes can influence the early development of preimplantation embryos. Expression of maternal and paternal genes is required for the completion of embryogenesis.

Clinical and molecular analyses of Beckwith-Wiedemann syndrome: Comparison between spontaneous conception and assisted reproduction techniques

Beckwith-Wiedemann syndrome (BWS) is an overgrowth syndrome characterized by an excessive prenatal and postnatal growth, macrosomia, macroglossia, and hemihyperplasia. The molecular basis of this syndrome is complex and heterogeneous, involving genes located at 11p15.5. BWS is correlated with assisted reproductive techniques. BWS in individuals born following assisted reproductive techniques has been found to occur four to nine times higher compared to children with to BWS born after spontaneous conception. Here, we report a series of 187 patients with to BWS born either after assisted reproductive techniques or conceived naturally. Eighty-eight percent of BWS patients born via assisted reproductive techniques had hypomethylation of KCNQ1OT1:TSS-DMR in comparison with 49% for patients with BWS conceived naturally. None of the patients with BWS born via assisted reproductive techniques had hypermethylation of H19/IGF2:IG-DMR, neither CDKN1 C mutations nor patUPD11. We did not find differences in the frequency of multi-locus imprinting disturbances between groups. Patients with BWS born via assisted reproductive techniques had an increased frequency of advanced bone age, congenital heart disease, and decreased frequency of earlobe anomalies but these differences may be explained by the different molecular background compared to those with BWS and spontaneous fertilization. We conclude there is a correlation of the molecular etiology of BWS with the type of conception. © 2016 Wiley Periodicals, Inc.

Epigenetics and Human Disease

Genetic causes for human disorders are being discovered at an unprecedented pace. A growing subclass of disease-causing mutations involves changes in the epigenome or in the abundance and activity of proteins that regulate chromatin structure. This article focuses on research that has uncovered human diseases that stem from such epigenetic deregulation. Disease may be caused by direct changes in epigenetic marks, such as DNA methylation, commonly found to affect imprinted gene regulation. Also described are disease-causing genetic mutations in epigenetic modifiers that either affect chromatin in trans or have a cis effect in altering chromatin configuration.

High Frequency of Imprinted Methylation Errors in Human Preimplantation Embryos

Assisted reproductive technologies (ARTs) represent the best chance for infertile couples to conceive, although increased risks for morbidities exist, including imprinting disorders. This increased risk could arise from ARTs disrupting genomic imprints during gametogenesis or preimplantation. The few studies examining ART effects on genomic imprinting primarily assessed poor quality human embryos. Here, we examined day 3 and blastocyst stage, good to high quality, donated human embryos for imprinted SNRPN, KCNQ1OT1 and H19 methylation. Seventy-six percent day 3 embryos and 50% blastocysts exhibited perturbed imprinted methylation, demonstrating that extended culture did not pose greater risk for imprinting errors than short culture. Comparison of embryos with normal and abnormal methylation didn’t reveal any confounding factors. Notably, two embryos from male factor infertility patients using donor sperm harboured aberrant methylation, suggesting errors in these embryos cannot be explained by infertility alone. Overall, these results indicate that ART human preimplantation embryos possess a high frequency of imprinted methylation errors.

Outlier DNA methylation levels as an indicator of environmental exposure and risk of undesirable birth outcome

We have identified a novel molecular phenotype that defines a subgroup of newborns who have highly disrupted epigenomes. We profiled DNA methylation in cord blood of 114 children selected from the lowest and highest quintiles of the birth weight distribution (irrespective of their mode of conception) at 96 CpG sites in genes we have found previously to be related to birth weight or growth and metabolism. We identified those individuals in each group who differed from the mean of the distribution by the greatest magnitude at each site and for the largest number of sites. Such 'outlier' individuals differ substantially from the rest of the group in having highly disrupted methylation levels at many CpG sites. We find that children from the lowest quintile of the birth weight distribution have a significantly greater number of disrupted CpGs than children from the highest quintile of the birth weight distribution. Among children from the lowest quintile of the birth weight distribution, 'outlier' individuals are significantly more common among children conceived in vitro than children conceived in vivo. These observations are novel and potentially important because they associate a molecular phenotype (multiple and large DNA methylation differences) in normal somatic tissues (cord blood) with both a prenatal exposure (conception in vitro) and a clinically important outcome (low birth weight). These observations suggest that some individuals are more susceptible to environmentally mediated epigenetic alterations than others.

Neural and behavioral epigenetics; what it is, and what is hype

The ability to examine epigenetic mechanisms in the brain has become readily available over the last 20 years. This has led to an explosion of research and interest in neural and behavioral epigenetics. Of particular interest to researchers, and indeed the lay public, is the possibility that epigenetic processes, such as changes in DNA-methylation and histone modification, may provide a biochemical record of environmental effects. This has led to some fascinating insights into how molecular changes in the brain can control behavior. However, some of this research has also attracted controversy and, as is dealt with here, some overblown claims. This latter problem is partly linked to the shifting sands of what is defined as 'epigenetics'. In this review, I provide an overview of what exactly epigenetics is, and what is hype, with the aim of opening up a debate as to how this exciting field moves forward.

Epigenetic alterations in sperm associated with male infertility

The most common form of male infertility is a low sperm count, known as oligozoospermia. Studies suggest that oligozoospermia is associated with epigenetic alterations. Epigenetic alterations in sperm, which may arise due to the exposure of gametes to environmental factors or those that pre-exist in the sperm of infertile individuals, may contribute to the increased incidence of normally rare imprinting disorders in babies conceived after assisted reproductive technology using the sperm of infertile men. Genomic imprinting is an important developmental process whereby the allelic activity of certain genes is regulated by DNA methylation established during gametogenesis. The aberrant expression of several imprinted genes has been linked to various diseases, malignant tumors, lifestyle and mental disorders in humans. Understanding how infertility and environmental factors such as reproductive toxicants, certain foods, and drug exposures during gametogenesis contribute to the origins of these disorders via defects in sperm is of paramount importance. In this review, we discuss the association of epigenetic alterations with abnormal spermatogenesis and the evidence that epigenetic processes, including those required for genomic imprinting, may be sensitive to environmental exposures during gametogenesis, fertilization and early embryonic development. In addition, we review imprinting diseases and their relationships with environmental factors. While the plasticity of epigenetic marks may make these more susceptible to modification by the environment, this also suggests that aberrant epigenetic marks may be reversible. A greater understanding of this process and the function of epidrugs may lead to the development of new treatment methods for many adult diseases in the future.

Sperm global DNA methylation level: association with semen parameters and genome integrity

Sperm DNA methylation abnormalities have been detected in oligozoospermic men. However, the association between sperm DNA methylation defects, sperm parameters and sperm DNA, and chromatin integrity remains poorly understood. This study was designed to clarify this issue. We recruited a cohort of 92 men (62 normozoospermic and 30 oligoasthenozoospermic) presenting for infertility evaluation during a 1-year period. Sperm global DNA methylation was evaluated by an ELISA-like method, DNA fragmentation was evaluated by flow cytometry-based terminal transferase dUTP nick end-labeling (TUNEL) assay (reported as DNA fragmentation index or DFI), and sperm denaturation was evaluated by aniline blue staining (reported as sperm denaturation index or SDI, a marker of chromatin compaction). We found a significant positive association between sperm global DNA methylation level and conventional sperm parameters (sperm concentration and motility), supported by the results of methylation analysis on H19-DMR. We also identified significant inverse relationships between sperm global DNA methylation, and, both DFI and SDI. However, sperm global DNA methylation level was not related to sperm vitality or morphology. Our findings suggest that global sperm DNA methylation levels are related to conventional sperm parameters, as well as, sperm chromatin and DNA integrity.

A physiological, rather than a superovulated, post-implantation environment can attenuate the compromising effect of assisted reproductive techniques on gene expression in developing mice embryos

Assisted reproductive techniques (ARTs) may perturb the pre-/peri-conception microenvironments, which subsequently threaten the health of offspring. This study aimed to investigate the effects of superovulation, vitrification, in vitro culture, and embryo transfer on the expression of epigenetic modulators, imprinted genes, and pluripotency markers in expanded blastocysts and Day-9.5 (D9.5) concepti. Results revealed that 53.4% (8/15) and 86.7% (13/15) of genes in the fetus and placenta, respectively, have similar patterns of transcription in all D9.5 concepti, despite the perturbed mRNA expression observed at the blastocyst stage for each embryo-production technique. These observations indicate a counterbalancing of the abnormal expression pattern analyzed at the blastocyst stage during post-implantation development, particularly when the uterus of a naturally synchronized foster mother is employed. Superovulation resulted in the most abnormal expression patterns compared to other treatment groups, although these same blastocysts were able to develop in a synchronized uterus. Thus, superovulation creates a hormonal environment that negatively affected gene expression and impairs fetal growth more adversely during post-implantation development than other ART protocols, such as in vitro culture, vitrification, or embryo transfer-although each did contribute negatively to the implantation and development process. Together, these results may have implications for treating infertility in humans.

The impact of assisted reproductive technologies on genomic imprinting and imprinting disorders

PURPOSE OF REVIEW

Genomic imprinting refers to preferential allele-specific gene expression. DNA methylation-based molecular mechanisms regulate establishment and maintenance of parental imprints during early embryo development and gametogenesis. Because of the coincident timing, a potential association between assisted reproductive technology (ART) procedures and imprinting defects has been investigated in various studies. In this review, we provide an overview of genomic imprinting and present a summary of the relevant clinical data.

RECENT FINDINGS

ART procedures affect DNA methylation pattern, parental imprinting status, and imprinted gene expression in the mouse embryo. In humans, several case series suggested an association between ART and imprinting disorders, with a three-fold to six-fold higher prevalence of ART use among children born with Beckwith-Wiedemann syndrome compared to the general population. However, more recent studies failed to support these findings and could not demonstrate an association between imprinting disorders and ARTs, independent of subfertility.

SUMMARY

ART procedures may affect methylation status of imprinted regions in the DNA, leading to imprinting disorders. Although the low prevalence of imprinting disorders makes it challenging to perform conclusive clinical trials, further studies in large registries are required to determine the real impact of ARTs on their occurrence.

Analysis of DNA Methylation Patterns in Single Blastocysts by Pyrosequencing®

Extensive epigenetic reprogramming occurs during mammalian gametogenesis and preimplantation development. DNA methylation patterns that are laid down during these stages are essential for subsequent normal foetal development. The requirement for more precise assessment of the epigenetic programming of in vitro-derived human preimplantation embryo has become of paramount importance following the identification of epigenetic diseases that are associated with assisted reproduction and/or infertility. Such techniques are also useful and applicable to experimental reproductive biology. In order to expand our knowledge of epigenetic marks, including DNA methylation, during mammalian reproduction and early development, it is necessary to test new and sufficiently sensitive protocols. There are, however, unique challenges to obtain DNA methylation data from the small cell numbers that are present in the preimplantation embryo. In this protocol, we describe the successful application of Pyrosequencing(®) to yield quantitative DNA methylation data over several CpG sites at differentially methylated regions (DMRs) at imprinted loci in single blastocysts, in this case, human blastocysts. Future developments of the protocol will allow DNA methylation analysis of a more extensive panel of genes for each embryo and at the same time, since the protocol allows for the extraction of mRNA from the embryo, the comparison between DNA methylation and gene expression.

Mowat-Wilson syndrome: deafness in the first Egyptian case who was conceived by intracytoplasmic sperm injection

Mowat-Wilson syndrome is a genetic disease caused by heterozygous mutations or deletions of the zinc finger E-box-binding homeobox 2 (ZEB2) gene. The syndrome is characterized by typical facial features, moderate-to-severe mental retardation, epilepsy and variable congenital malformations, including Hirschsprung disease, genital anomalies, congenital heart disease, agenesis of the corpus callosum, and eye defects. The prevalence of Mowat-Wilson syndrome is currently unknown, but it seems that Mowat-Wilson syndrome is underdiagnosed, particularly in patients without Hirschsprung disease. We report here the first Egyptian case of Mowat-Wilson syndrome who was conceived by intracytoplasmic sperm injection. The patient manifested bilateral sensorineural hearing loss--a new feature not previously reported in cases of Mowat-Wilson syndrome. This report describes the first Egyptian patient of Mowat-Wilson syndrome who was conceived after intracytoplasmic sperm injection, and provides a new evidence for the inclusion of deafness among the congenital defects of the syndrome.

Early developmental conditioning of later health and disease: physiology or pathophysiology?

Extensive experimental animal studies and epidemiological observations have shown that environmental influences during early development affect the risk of later pathophysiological processes associated with chronic, especially noncommunicable, disease (NCD). This field is recognized as the developmental origins of health and disease (DOHaD). We discuss the extent to which DOHaD represents the result of the physiological processes of developmental plasticity, which may have potential adverse consequences in terms of NCD risk later, or whether it is the manifestation of pathophysiological processes acting in early life but only becoming apparent as disease later. We argue that the evidence suggests the former, through the operation of conditioning processes induced across the normal range of developmental environments, and we summarize current knowledge of the physiological processes involved. The adaptive pathway to later risk accords with current concepts in evolutionary developmental biology, especially those concerning parental effects. Outside the normal range, effects on development can result in nonadaptive processes, and we review their underlying mechanisms and consequences. New concepts concerning the underlying epigenetic and other mechanisms involved in both disruptive and nondisruptive pathways to disease are reviewed, including the evidence for transgenerational passage of risk from both maternal and paternal lines. These concepts have wider implications for understanding the causes and possible prevention of NCDs such as type 2 diabetes and cardiovascular disease, for broader social policy and for the increasing attention paid in public health to the lifecourse approach to NCD prevention.

Imprinting methylation errors in ART

There has been an increase in incidence reports of rare imprinting disorders associated with assisted reproductive technology (ART). ART, including in vitro fertilization and intracytoplasmic sperm injections, is an important treatment for infertile people of reproductive age and increasingly produces children. The identification of epigenetic changes at imprinted loci in ART infants has led to the suggestion that ART techniques themselves may predispose embryos to acquire imprinting errors and diseases. In this review, we note that the particular steps of ART may be prone to induction of imprinting methylation errors during gametogenesis, fertilization and early embryonic development. In addition, we explain imprint-associated diseases and their causes. Moreover, from a Japanese nationwide epidemiological study of imprint-associated diseases, we determine their associations with ART. Epigenetic studies will be required to understand the pathogenesis, ART-related risk factor(s) and what precautions can be taken to prevent the occurrence of input methylation errors. We hope that the constitution of children born after each ART procedure will reveal the safest and most ethical approach to use, which will be invaluable for the future development of standard ART.

Assisted reproductive techniques

Assisted reproductive technologies (ART) encompass fertility treatments, which involve manipulations of both oocyte and sperm in vitro. This chapter provides a brief overview of ART, including indications for treatment, ovarian reserve testing, selection of controlled ovarian hyperstimulation (COH) protocols, laboratory techniques of ART including in vitro fertilization (IVF), and intracytoplasmic sperm injection (ICSI), embryo transfer techniques, and luteal phase support. This chapter also discusses potential complications of ART, namely ovarian hyperstimulation syndrome (OHSS) and multiple gestations, and the perinatal outcomes of ART.

Epigenetic regulation of the RHOX homeobox gene cluster and its association with human male infertility

The X-linked RHOX cluster encodes a set of homeobox genes that are selectively expressed in the reproductive tract. Members of the RHOX cluster regulate target genes important for spermatogenesis promote male fertility in mice. Studies show that demethylating agents strongly upregulate the expression of mouse Rhox genes, suggesting that they are regulated by DNA methylation. However, whether this extends to human RHOX genes, whether DNA methylation directly regulates RHOX gene transcription and how this relates to human male infertility are unknown. To address these issues, we first defined the promoter regions of human RHOX genes and performed gain- and loss-of-function experiments to determine whether human RHOX gene transcription is regulated by DNA methylation. Our results indicated that DNA methylation is necessary and sufficient to silence human RHOX gene expression. To determine whether RHOX cluster methylation associates with male infertility, we evaluated the methylation status of RHOX genes in sperm from a large cohort of infertility patients. Linear regression analysis revealed a strong association between RHOX gene cluster hypermethylation and three independent types of semen abnormalities. Hypermethylation was restricted specifically to the RHOX cluster; we did not observe it in genes immediately adjacent to it on the X chromosome. Our results strongly suggest that human RHOX homeobox genes are under an epigenetic control mechanism that is aberrantly regulated in infertility patients. We propose that hypermethylation of the RHOX gene cluster serves as a marker for idiopathic infertility and that it is a candidate to exert a causal role in male infertility.

Health outcomes of children born after IVF/ICSI: a review of current expert opinion and literature

The Sixth Evian Annual Reproduction (EVAR) Workshop Group Meeting was held to evaluate the impact of IVF/intracytoplasmic sperm injection on the health of assisted-conception children. Epidemiologists, reproductive endocrinologists, embryologists and geneticists presented data from published literature and ongoing research on the incidence of genetic and epigenetic abnormalities and congenital malformations in assisted-conception versus naturally conceived children to reach a consensus on the reasons for potential differences in outcomes between these two groups. IVF-conceived children have lower birthweights and higher peripheral fat, blood pressure and fasting glucose concentrations than controls. Growth, development and cognitive function in assisted-conception children are similar to controls. The absolute risk of imprinting disorders after assisted reproduction is less than 1%. A direct link between assisted reproduction and health-related outcomes in assisted-conception children could not be established. Women undergoing assisted reproduction are often older, increasing the chances of obtaining abnormal gametes that may cause deviations in outcomes between assisted-conception and naturally conceived children. However, after taking into account these factors, it is not clear to what extent poorer outcomes are due to the assisted reproduction procedures themselves. Large-scale, multicentre, prospective epidemiological studies are needed to investigate this further and to confirm long-term health consequences in assisted-conception children. Assisted reproduction treatment is a general term used to describe methods of achieving pregnancy by artificial means and includes IVF and sperm implantation. The effect of assisted reproduction treatment on the health of children born using these artificial methods is not fully understood. In April 2011, fertility research experts met to give presentations based on research in this area and to look carefully at the evidence for the effects of assisted reproduction treatment on children's health. The purpose of this review was to reach an agreement on whether there are differences in the health of assisted-conception children with naturally conceived children. The researchers discovered no increased risk in birth defects in assisted-conception children compared with naturally conceived children. They found that IVF-conceived children have lower birth weights and higher fat under the skin, higher blood pressure and higher fasting glucose concentrations than naturally conceived children; however, growth, development and cognitive function are similar between groups. A very low risk of disorders of genetic control was observed in assisted-conception children. Overall, there did not appear to be a direct link between assisted reproduction treatment and children's health. The researchers concluded that the cause of some differences in the health of children conceived using assisted reproduction treatment may be due to the age of the woman receiving treatment. Large-scale, research studies are needed to study the long-term health of children conceived using assisted reproduction treatment.

Stability of genomic imprinting and gestational-age dynamic methylation in complicated pregnancies conceived following assisted reproductive technologies

For the past three decades, assisted reproductive technologies (ART) have revolutionized infertility treatments. The use of ART is thought to be safe. However, early investigations suggested that children born as a result of ART had higher risk of diseases with epigenetic etiologies, including imprinting disorders caused by a lack of maternal methylation at imprinting control elements. In addition, large epidemiology studies have highlighted an increased risk of obstetric complications, including severe intrauterine growth restriction (IUGR) in babies conceived using ART. It is plausible that the increased frequency of IUGR may be due to abnormal imprinting because these transcripts are key for normal fetal growth and development. To address this, we have collected a large cohort of placenta and cord blood samples from ART conceptions and compared the imprinting status with appropriate non-ART population. Using a custom DNA methylation array that simultaneously quantifies 25 imprinted differentially methylated regions, we observed similar epigenetic profiles between groups. A multiplex Sequenom iPLEX allelic expression assay revealed monoallelic expression for 11 imprinted transcripts in our placenta cohort. We also observe appropriate gestational age-dependent methylation dynamics at retrotransposable elements and promoters associated with growth genes in ART placental biopsies. This study confirms that children conceived by ART do not show variability in imprinted regulation and that loss-of-imprinting is not commonly associated with nonsyndromic IUGR or prematurity.

Are imprinting disorders more prevalent after human in vitro fertilization or intracytoplasmic sperm injection?

OBJECTIVE

To review the literature and present original data to answer the question of whether in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) is associated with an increase in imprinted diseases in offspring. If the answer is positive, to investigate whether there is a causal relationship between IVF or ICSI and the imprinted diseases.

DESIGN

Review study.

RESULT(S)

Eight epidemiologic studies were suitable to calculate the weighted relative risk for the birth of a child with Beckwith-Wiedemann syndrome following IVF or ICSI compared with the risk in the normal population. This relative risk was 5.2 (95% CI 1.6-7.4). In one study the relative risk was corrected for parents' fertility problems and no significant association was found. Data on the Silver-Russell syndrome are too sparse to draw conclusions, but a positive association with IVF or ICSI treatment is probable. No significant associations were found between the incidences of the Angelman and Prader-Willi syndromes and IVF or ICSI treatments. Children with Prader-Willi syndrome or Angelman syndrome are more likely to be born to parents with fertility problems. All retinoblastomas in children born after IVF or ICSI could be explained by de novo mutations in the RB1 gene and were not associated with imprinted genes. Imprinted diseases result from methylation errors already present in sperms or oocytes. There is no proof of a causal relationship between imprinted diseases and IVF or ICSI treatments.

CONCLUSION(S)

Imprinting disorders are more prevalent after human IVF or ICSI. Future studies should correct for fertility problems in the affected and comparison groups. It is highly improbable that assisted reproduction technologies cause imprinted diseases in humans.