Imprinting Disorders In Children Research Articles

Imprinting disorders in children conceived with assisted reproductive technology in Sweden

ObjectiveTo assess whether the use of assisted reproductive technology for conception is associated with imprinting disorders in children and the impact of parental factors related to infertility. DesignA nationwide register-based cohort study. SubjectsAll liveborn singletons in Sweden (N = 2 084 127) between 1997-2017 with follow-up to December 31, 2018. ExposureThe use of specific methods implemented in the assisted reproductive technology Main Outcome MeasuresThe International Classification of Diseases version 10 was used to identify three distinct imprinting disorder groups: Prader-Willi/Silver-Russell syndrome, Beckwith-Wiedemann syndrome, and central precocious puberty. The Cox model combined with inverse probability treatment weights were used to estimate weighted hazard ratio (wHR) with 95% confidence interval (CI), accounting for multiple confounders. ResultsA total of 1044 children were diagnosed with the disorders of interest, and 52 of them were conceived with assisted reproductive technology. The overall risk of being diagnosed with any of the studied imprinting disorders was elevated in children conceived with ART compared to all other children (HR 1.84, 95% CI: 1.38-2.45). After adjusting for parental background factors, the association was partially attenuated (wHR 1.50, 95% CI: 0.97-2.32), but remained also in the weighted comparison restricted to children of couples with known infertility (wHR 1.52, 95% CI: 1.05-2.21). For the specific diagnoses of Prader-Willi/Silver-Russell syndrome and Beckwith-Wiedemann syndrome, compared to children of couples with known infertility, children conceived with assisted reproductive technology showed a small excess risk, which could not be distinguished from the null (wHR 1.56 [95% CI: 0.93-2.62] and 1.80 [95% CI: 0.99-3.28], respectively). Further subgroup analysis showed that the combined use of intra-cytoplasmic sperm injection and cryopreserved embryos was associated with higher risk of both Prader-Willi/Silver-Russell syndrome (wHR 4.60, 95% CI: 1.72-12.28) and Beckwith-Wiedemann syndrome (wHR 6.69, 95% CI: 2.09-21.45). The number of central precocious puberty cases in children conceived with assisted reproductive technology was too small (N=3) to make any meaningful inference. ConclusionThe combined use of intra-cytoplasmic sperm injection and cryopreserved embryos was associated with small elevated risks of Prader-Willi/Silver-Russell syndrome and Beckwith-Wiedemann syndrome in children, independent of parental factors related to infertlity.

Genome-wide assessment of DNA methylation alterations induced by superovulation, sexual immaturity and in vitro follicle growth in mouse blastocysts

BackgroundIn their attempt to fulfill the wish of having children, women who suffer from fertility issues often undergo assisted reproductive technologies such as ovarian stimulation, which has been associated with adverse health outcomes and imprinting disorders in children. However, given the crucial role of exogenous hormone stimulation in improving human infertility treatments, a more comprehensive analysis of the potential impacts on DNA methylation in embryos following ovarian stimulation is needed. Here, we provide genome-wide DNA methylation profiles of blastocysts generated after superovulation of prepubertal or adult mice, compared with blastocysts derived from non-stimulated adult mice. Additionally, we assessed the impact of the in vitro growth and maturation of oocytes on methylation in blastocysts.ResultsNeither hormone stimulation nor sexual maturity had an impact on the low global methylation levels characteristic of the blastocyst stage or was associated with extensive DNA methylation alterations. However, we found hormone- and age-associated changes at specific positions but dispersed throughout the genome. In particular, we detected anomalous methylation at a limited number of CpG islands. Additionally, superovulation in adult mice was associated with alterations at the Sgce and Zfp777 imprinted genes. On the other hand, in vitro culture of follicles from the early pre-antral stage was associated with globally reduced methylation and increased variability at imprinted loci in blastocysts.ConclusionsOur results indicate a minimal effect of ovarian stimulation of adult and prepubertal mice on the DNA methylation landscape attained at the blastocyst stage, but potentially greater impacts of in vitro growth and maturation of oocytes. These findings have potential significance for the improvement of assisted reproductive techniques, in particular for those related to treatments in prepubertal females, which could be crucial for improving human fertility preservation strategies.

ALTERED BLASTOCYST METHYLOME AND IMPRINTING DYSREGULATION ASSOCIATED WITH THE PROLONGED DISEASE STATE OF INFERTILITY

The increased incidence of rare imprinting disorders in children born following infertility treatments has led to questions regarding the origin of this observed epigenetic dysregulation. Epidemiological studies suggest that the underlying disease state and severity of infertility plays a significant role. Imprinting disorders frequently arise from DNA methylation errors at imprinting control regions (ICRs), leading to our investigation of the euploid blastocyst methylome in association with duration of infertility (time to pregnancy; TTP). Research study. Surplus cryopreserved euploid blastocysts of transferrable quality (grade ≥3BB; n=104) were donated with IRB approval and patient consent. Blastocysts were grouped based on TTP; months of reported primary infertility prior to oocyte retrieval that resulted in a live birth (Fertile Control: 0 months, donor oocyte/donor sperm; Infertile Short: 12-24 months; Infertile Intermediate: 36-48 months; Infertile Long: ≥60 months). Patient demographics and total gonadotropin doses were comparable between groups. Individual blastocyst DNA underwent whole genome bisulfite sequencing (Methyl-MaxiSeq; Zymo Research) with significant methylated CpGs determined by Student’s t-test adjusted using Benjamini-Hochberg FDR; q<0.05. Methylation validation of ICRs was performed by pyrosequencing (PyroMark Q24 Advanced; Qiagen) with significance determined by Student’s t-test and one-way ANOVA where appropriate; p<0.05. Quantitative RT-PCR was utilized on individual blastocysts for gene expression analysis with REST 2009 Software (Qiagen) and significance determined by a pairwise fixed reallocation randomization test; p<0.05. Prolonged TTP (Infertile Long ≥60 months) resulted in 6,609 significantly altered CpGs compared with blastocysts from Fertile Controls (0 months; q<0.05). Significant CpGs were situated at five ICRs, including KvDMR and MEST, and 36 imprinted genes, with NFAT signaling identified as the top canonical pathway (62/221 genes, q=1.28E-08). Overall, extended TTP ≥36 months (mean=65 months) exhibited significant hypomethylation compared to shorter TTP ≤24 months (mean=10 months) for KvDMR (39% Extended vs. 48% Shorter; p<0.05), MEST (40% Extended vs. 49% Shorter; p<0.05), and H19 (29% Extended vs. 41% Shorter; p<0.05) while SNRPN trended downward without significance. Significant decreases in expression were observed for maternally imprinted genes (KCNQ1OT1, MEST, COPG2, DNMT1; p<0.05), and significant increases in expression for paternally imprinted genes (H19, CDKN1C; p<0.05). This novel study is the first to report evidence that an extended duration of infertility correlates with altered methylation in euploid blastocysts, with a particular emphasis on genomic imprinting. Our results provide evidence to support an association between imprinting dysregulation and infertility as a prolonged disease.

Imprinting disorders in children born after ART: a Nordic study from the CoNARTaS group.

Is the risk of imprinting disorders increased in children conceived after ART? We found an adjusted odds ratio (AOR) of 2.84 [95% CI: 1.34-6.01] for Beckwith-Wiedemann syndrome in ART children, while the risk of Prader-Willi syndrome, Silver-Russell syndrome or Angelman syndrome was not increased in children conceived after ART. Earlier studies, most of them small, have suggested an association between ART and imprinting disorders. This was a binational register-based cohort study. All children conceived by ART in Denmark (n= 45 393, born between 1994 and 2014) and in Finland (n= 29 244, born between 1990 and 2014) were identified. The full background populations born during the same time periods in the two countries were included as controls. Odds ratios of imprinting disorders in ART children compared with naturally conceived (NC) children were calculated. The median follow-up time was 8years and 9months for ART children and 11years and 9months for NC children. From the national health registries in Denmark and Finland, we identified all children diagnosed with Prader-Willi syndrome (n= 143), Silver-Russell syndrome (n= 69), Beckwith-Wiedemann syndrome (n= 105) and Angelman syndrome (n= 72) born between 1994/1990 and 2014, respectively. We identified a total of 388 children diagnosed with imprinting disorders; 16 of these were conceived after ART. The overall AOR for the four imprinting disorders in ART children compared with NC children was 1.35 [95% CI: 0.80-2.29], but since eight ART children were diagnosed with Beckwith-Wiedemann syndrome, the AOR for this specific imprinting disorder was 2.84 [95% CI: 1.34-6.01]. The absolute risk of Beckwith-Wiedemann syndrome in children conceived after ART was still low: 10.7 out of 100 000 newborns. The risks of Prader-Willi syndrome, Silver-Russell syndrome and Angelman syndrome were not increased in children conceived after ART. Imprinting disorders are rare events and our results are based on few ART children with imprinting disorders. The aetiology is complex and only partly clarified, and the clinical diagnoses are challenged by a broad phenotypic spectrum. In the existing studies, results on the risk of imprinting disorders in children conceived after ART are ambiguous. This study adds that the risk of imprinting disorders in ART children is very small and perhaps restricted to Beckwith-Wiedemann syndrome. This work was supported by the Nordic Trial Alliance: a pilot project jointly funded by the Nordic Council of Ministers and NordForsk (grant number: 71450), the Nordic Federation of Obstetrics and Gynecology (grant numbers: NF13041, NF15058, NF16026 and NF17043) and the Interreg Öresund-Kattegat-Skagerak European Regional Development Fund (ReproUnion project). The authors have no conflicts of interest related to this work. N/A.

Assisted Reproductive Technology and Epigenetics.

Assisted reproductive technology (ART) is responsible for 1.7% of births in the United States annually. Despite a large number of studies promoting the efficacy and safety of these practices, there have been reports of imprinting disorders occurring at higher frequencies in children born through ART. Driven by findings in animal studies, it has been postulated that various ART procedures employed at critical points in embryonic development may predispose the genomic imprinting process to errors. Alterations in DNA methylation patterns at imprinting control centers have been reported by some studies to occur more frequently in children with imprinting disorders conceived by ART compared with spontaneous conception, though these findings are not consistently demonstrated and controversy has surrounded the strength of these associations. The rarity of imprinting disorders with a reliance of studies on disease registry cohorts, wide variations in ART protocols, and a lack of proper control groups limit the ability to substantiate associations between imprinting disorders and ART. Large, prospective cohort studies with a focus on molecular etiologies of these conditions are needed to discern whether a true association exists. Based on current evidence, the absolute risk of imprinting disorders after ART is low and screening for imprinting disorders in children conceived by ART is not warranted.

Imprinting alterations in sperm may not significantly influence ART outcomes and imprinting patterns in the cord blood of offspring.

An increase in imprinting disorders in children conceived though assisted reproductive technologies (ARTs) has been the subject of several reports. The transmission of imprinting errors from the sperm of infertile fathers is believed to be a possible reason for the increased occurrence of these disorders. However, whether the imprinting alterations in sperm affect ART outcomes and the imprinting of offspring is unclear. In the current study, we analyzed the methylation of H19, SNRPN and KCNQ1OT1 by pyrosequencing sperm samples from 97 infertile patients and 31 proven fertile males as well as cord blood samples from 13 infantswho were conceived by infertile parents through intracytoplasmic sperm injection (ICSI) and 30 healthy newborns who were conceived naturally. After four cases were excluded owing to the lack of a sequencing signal, the infertile patients were subgrouped into normal (69 cases) and abnormal (24 cases) imprinting groups according to the reference range set by the control group. Between the groups, there were no significant differences in ART outcomes. Significantly different levels of methylation were detected in H19, but none of the imprinted genes were determined to be outside of the methylation reference range set by the values derived from the naturally conceived controls. Three CpG loci were found to be significantly hypomethylated in the maternally imprinted gene KCNQ1OT1 in two patients from the abnormal imprinting group, none of which were caused by sperm imprinting errors. In addition, the paternal H19 gene exhibited discrepant methylation patterns between the sperm controls and the cord blood controls. Our data suggest that increased imprinting errors in the sperm of infertile patients do not have an obvious influence on ART outcomes or the imprinting of offspring.

Compromised oocyte quality and assisted reproduction contribute to sex-specific effects on offspring outcomes and epigenetic patterning.

Clinical studies have revealed an increased incidence of growth and genomic imprinting disorders in children conceived using assisted reproductive technologies (ARTs), and aberrant DNA methylation has been implicated. We propose that compromised oocyte quality associated with female infertility may make embryos more susceptible to the induction of epigenetic defects by ART. DNA methylation patterns in the preimplantation embryo are dependent on the oocyte-specific DNA methyltransferase 1o (DNMT1o), levels of which are decreased in mature oocytes of aging females. Here, we assessed the effects of maternal deficiency in DNMT1o (Dnmt1Δ1o/+) in combination with superovulation and embryo transfer on offspring DNA methylation and development. We demonstrated a significant increase in the rates of morphological abnormalities in offspring collected from Dnmt1Δ1o/+ females only when combined with ART. Together, maternal oocyte DNMT1o deficiency and ART resulted in an accentuation of placental imprinting defects and the induction of genome-wide DNA methylation alterations, which were exacerbated in the placenta compared to the embryo. Significant sex-specific trends were also apparent, with a preponderance of DNA hypomethylation in females. Among genic regions affected, a significant enrichment for neurodevelopmental pathways was observed. Taken together, our results demonstrate that oocyte DNMT1o-deficiency exacerbates genome-wide DNA methylation abnormalities induced by ART in a sex-specific manner and plays a role in mediating poor embryonic outcome.

A systematic review and meta-analysis of DNA methylation levels and imprinting disorders in children conceived by IVF/ICSI compared with children conceived spontaneously.

Increasing numbers of children are being conceived by assisted reproductive technology (ART). A number of studies have highlighted an altered epigenetic status in gametes from infertile couples and the possibility of an increased risk of imprinting defects and somatic epigenetic changes in ART conceived children, but the results have been heterogeneous. We performed a systematic review of existing studies to compare the incidence of imprinting disorders and levels of DNA methylation in key imprinted genes in children conceived through in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) with those in children conceived spontaneously. A detailed search strategy was used to conduct electronic literature searches (spanning 1978 to 2013) on Medline, EMBASE, the Cochrane Library and Web of Science. Abstracts of relevant conference papers were identified. As randomized trials are not feasible in this context, we included observational (cohort and case-control) studies comparing outcomes in children conceived through ART with those conceived spontaneously, irrespective of the language of publication. The outcome measures were DNA methylation and the incidence of imprinting disorders. A total of 351 publications were identified by the initial search. Of these, 26 were excluded as duplicates and 241 were excluded after reviewing the abstracts, then of those remaining 66 were excluded after review of the full text. A total of 18 papers were included in the review. Apart from one case-control study, all were cohort studies. There was a degree of clinical heterogeneity in terms of the study population, type of infertility treatment, and samples obtained from exposed and unexposed children. DNA methylation levels were either presented as categorical data (hypo-, hyper- or normally methylated DNA) or continuous data (i.e. percentage of methylated DNA). The combined odds ratio (95% confidence intervals) of any imprinting disorder in children conceived through ART was 3.67 (1.39, 9.74) in comparison with spontaneously conceived children. Meta-analysis of data from relevant studies revealed that the weighted mean difference (95% confidence intervals) in methylation percent between IVF/ICSI versus spontaneously conceived children were as follows: H19: -0.46(-1.41, 0.49), PEG1-MEST: 0.47 (-2.07, 3.01), GRB10: -0.05 (-0.43, 0.33), IGF2: -0.15 (-1.09, 0.79), SNRPN: -0.55 (-1.55, 0.46), KvDMR/KCNQ10T1: -0.16 (-0.34, 0.02) and PEG3: -0.24 (-1.72, 1.24). There was an increase in imprinting disorders in children conceived though IVF and ICSI but insufficient evidence for an association between ART and methylation in other imprinted genes. Heterogeneity in the types of fertility treatment, the imprinted regions studied, the tissues used and the methods of measurement, reduce our ability to assess the full effect of ART on DNA methylation and imprinting. More controlled studies, using standardized methodologies, in larger, better clinically defined populations are needed.

Frequency of Prader–Willi syndrome in births conceived via assisted reproductive technology

PurposePrader-Willi syndrome (PWS) is an imprinting disorder characterized by typical facial, physical and cognitive/behavioral features, resulting from lack of paternally-expressed genes on chromosome 15q11.2-q13. Studies have suggested an increased risk of other imprinting disorders in children conceived by assisted reproductive techniques (ART). This study was designed to determine the association between ART and PWS.MethodsData on individuals with PWS were collected from three distinct sources and the proportion of ART-births analyzed.ResultsThe proportion of ART-births in the Prader-Willi Syndrome Association [PWSA (USA)], Rare Diseases Clinical Research Network (RDCRN), and University of California, Irvine Medical Center (UCIMC) populations was 1.0% (18/1,736), 1.0% (1/98), and 2.0% (1/50), respectively (overall 1.1%; population frequency for the U.S was 1.0%). Interestingly, 2.4% (45/1,898) of participants were co-twins (eleven born after ART procedures); U.S. twin frequency is 1.6% (p=0.007). The proportion of individuals with maternal disomy 15/imprinting defects born after ART was higher than in the total sample, 55.6% (10/18) and 34.5% (431/1,250), respectively.ConclusionThis study found no association between ART and PWS. There was an increased frequency of twinning. The number of individuals with maternal disomy 15/imprinting defect was nearly double in the ART group compared to the total PWS participants.

Role of ART in Imprinting Disorders

Assisted reproductive technologies (ART) offer revolutionary infertility treatments for millions of childless couples around the world. Currently, ART accounts for 1 to 3% of annual births in industrialized countries and continues to expand rapidly. Except for an increased incidence of premature births, these technologies are considered safe. However, new evidence published during the past decade has suggested an increased incidence of imprinting disorders in children conceived by ART. Specifically, an increased risk was reported for Beckwith-Wiedemann syndrome (BWS), Angelman syndrome (AS), Silver-Russell syndrome, and retinoblastoma. In contrast, some studies have found no association between ART and BWS, AS, Prader-Willi syndrome, transient neonatal diabetes mellitus, and retinoblastoma. The variability in ART protocols and the rarity of imprinting disorders complicate determining the causative relationship between ART and an increased incidence of imprinting disorders. Nevertheless, compelling experimental data from animal studies also suggest a link between increased imprinting disorders and ART. Further comprehensive, appropriately powered studies are needed to better address the magnitude of the risk for ART-associated imprinting disorders. Large longitudinal studies are particularly critical to evaluate long-term effects of ART not only during the perinatal period but also into adulthood. An important consideration is to determine if the implicated association between ART and imprinting disorders is actually related to the procedures or to infertility itself.

Russell–Silver syndrome due to paternal H19/IGF2 hypomethylation in a patient conceived using intracytoplasmic sperm injection

Epigenetic alterations at several maternal loci have been associated with imprinting disorders in children conceived using assisted reproductive technologies. To date, epimutations at paternal loci have been observed in the spermatozoa of infertile men, but there is little evidence of paternal epimutations in babies conceived using assisted reproductive treatment. This is a report of a female infant with classic Russell-Silver Syndrome (RSS) who was conceived using intracytoplasmic injection of spermatozoa obtained from testicular aspiration. Methylation studies revealed hypomethylation of the paternally derived H19/IGF2 locus. As far as is known, this is the second assisted reproduction treatment-conceived patient with classic RSS and this epigenotype. This case provides further evidence that epimutations affecting paternal alleles might be associated with assisted reproductive treatment.

Widespread genomic DNA methylation changes are not apparent at the blastocyst stage in ART versus normally conceived mice

OBJECTIVE: Existing data indicate that assisted reproductive technologies (ART) may result in alterations in genomic methylation at specific loci, as evidenced by animal models and an increased incidence of imprinting disorders in children conceived via ART. We have previously presented preliminary evidence demonstrating that ART conditions may also result in global alterations of genomic methylation in murine blastocysts. We now present microarray data to further test this hypothesis.

Abnormal methylation at the KvDMR1 imprinting control region in clinically normal children conceived by assisted reproductive technologies

Genomic imprinting alterations have been shown to be associated with assisted reproductive technologies (ARTs) in animals. At present, data obtained in humans are inconclusive; however, some epidemiological studies have demonstrated an increased incidence of imprinting disorders in children conceived by ARTs. In the present study, we focused on the effect of ARTs [IVF and intracytoplasmic sperm injection (ICSI)] on the epigenetic reprogramming of the maternally methylated imprinting control region KvDMR1 in clinically normal children. Qualitative and quantitative methylation at KvDMR1 were assessed by the methylation-specific PCR approach and by the methylation-sensitive enzymatic digestion associated with real-time PCR method, respectively. DNA was obtained from peripheral blood of 12/18 and umbilical cord blood and placenta of 6/18 children conceived by IVF or ICSI. The methylation patterns observed in this group were compared with the patterns observed in 30 clinically normal naturally conceived children (negative controls) and in 3 naturally conceived Beckwith-Wiedemann syndrome patients (positive controls). Hypomethylation at KvDMR1 was observed in 3/18 clinically normal children conceived by ARTs (2 conceived by IVF and 1 by ICSI). A discordant methylation pattern was observed in the three corresponding dizygotic twins. Our findings corroborate the hypothesis of vulnerability of maternal imprinting to ARTs. Furthermore, the discordant methylation at KvDMR1 observed between dizygotic twins could be consequent to one of the following possibilities: (i) a differential vulnerability of maternal imprints among different embryos; or (ii) epimutations that occurred during gametogenesis resulting in the production of oocytes without the correct primary imprint at KvDMR1.

Imprinting disorders and assisted reproductive technology

To review currently available literature on the association between imprinting disorders (Beckwith-Wiedemann syndrome [BWS], Angelman syndrome [AS] and retinoblastoma) and assisted reproductive technology (ART) in humans. Publications related to imprinting/epigenetic disorders including BWS, AS, and retinoblastoma with ART, as well as articles publishing outcome of ART, including IVF and ICSI from July 1978 to February 2008, were identified using PubMed, Medline, and EMBASE. Considerable evidence in animal studies has demonstrated alteration in gene imprinting of embryos cultured in vitro. Publications from Europe, the United States, and Australia have suggested an association between ART and BWS. Importantly, more than 90% of children with BWS that were born after ART had imprinting defects, compared with 40%-50% of children with BWS and conceived without ART. Moreover, there have been other reports suggesting an association between AS and ART. The majority of children with AS born after ART had an imprinting defect as the underlying etiology, specifically loss of methylation of the maternal allele. There was a single report suggesting an increased incidence of retinoblastoma in children conceived with ART. Because the absolute incidence of imprinting disorders is small (<1:12,000 births), routine screening for imprinting disorders in children conceived by ART is not recommended. Additional large cohort studies of children born after ART are needed to determine whether there is a genuine association between ART and imprinting disorders.

Malignant Conditions in Children Born After Assisted Reproductive Technology

This article reviews the risks of childhood malignancies and imprinting disorders in children born after assisted reproductive technology (ART). It is recognized that there is a theoretical potential of developing an excess of malignancies in children born after ART. With the advancement and introduction of newer techniques in ART there is an increase in the micromanipulation of gametes and embryos in vitro and extended exposure to the in vitro environment. These include the use of gonadotropins for superovulation, intracytoplasmic sperm injection, blastocyst culture, assisted hatching, and preimplantation genetic diagnosis. Although these approaches aim to enhance pregnancy rates and its outcome, the risk of associated long-term health hazards cannot be disregarded. More recently there is some evidence suggesting a link between ART and epigenetic alterations leading to DNA modifications and imprinting disorders. Two of these genetic imprinting disorders that are known to cause birth defects and childhood malignancies, Beckwith-Wiedmann syndrome and Angelman syndrome have been associated with ART. Systemic reviews of the literature identified published studies, but were unable to identify the precise risks of imprinting disorders and childhood cancers in children conceived with ART. Overall, most studies have not shown any increase in the incidence of childhood cancers after ART. With more women resorting to ART, careful counseling should be offered to all couples especially those requiring intracytoplasmic sperm injection for abnormal sperm parameters. Obstetricians & Gynecologists, Family Physicians. After completion of this article, the reader should be able to distinguish for patients the lack of irrefutable evidence for an increased risk of childhood malignancies in children conceived using assisted reproductive technology (ART), explain potential mechanisms of injury to the gametes and/or embryo during ART which might predispose to childhood illness, and appraise future articles on this topic for credibility both to likelihood of true relationship to possible childhood cancers as well as biologic basis for potential relationship.

A survey of assisted reproductive technology births and imprinting disorders

Genomic imprinting is an epigenetic process in which allele-specific gene expression is dependent on the parental inheritance. Although only a minority of human genes are imprinted, those that have been identified to date have been preferentially implicated in prenatal growth and neurodevelopment. Mutations or epimutations in imprinted genes or imprinting control centres are associated with imprinting disorders such as Angelman syndrome (AS) and Beckwith-Wiedemann syndrome (BWS). Recently, an increased frequency of assisted reproductive technology (ART) conceptions has been reported in children with BWS and AS. However, the risk of imprinting disorders in ART children is unknown. We undertook a survey of 2492 children born after ART in the Republic of Ireland and Central England with the aim of detecting cases (both clinically diagnosed and previously unrecognized) of BWS and AS in this cohort. The response rate to an initial questionnaire was 61%, corresponding to data for 1524 children. After evaluation of the questionnaire, 70 children were invited for a detailed clinical assessment, and 47 accepted (response rate of 67%). In this entire cohort, we detected one case of BWS and no cases of AS. We did not find evidence that there exists a significant group of ART children with unrecognized milder forms of AS or BWS. Although previous studies have suggested an increased relative risk of BWS and AS after ART, our findings suggest that the absolute risk of imprinting disorders in children conceived by ART is small (<1%). Precise risk estimates of risk are difficult to define because of the rarity of the conditions and incomplete response rates to the questionnaire and clinical examination invitations. Hence further investigations are indicated to (i) refine the absolute and relative risks of imprinting disorders after ART and (ii) ensure that changes in ART protocols are not associated with increased frequencies of epigenetic changes and imprinting disorders in children born after ART.