Novel fetal and maternal sonographic findings in confirmed cases of Beckwith-Wiedemann syndrome

Third-trimester fetal pancreas imaging in uncomplicated pregnancies and association with pregnancy outcomes

OBJECTIVE

To examine third-trimester sonographic imaging of the fetal pancreas in uncomplicated pregnancies and its association with pregnancy outcomes.

METHODS

This was a prospective cohort study including 274 pregnant women. Uncomplicated pregnancies in the third trimester (28-40 weeks) were included in the study. Maternal chronic disease, pregnancy-related disorders such as hypertension, diabetes, cholestasis, smoking, and fetal abnormalities were determined as exclusion criteria. Sonographic fetal pancreatic measurement and echogenicity were evaluated in all participants. For intra-observer reliability, each participant's fetal pancreatic circumference was measured two times. The echogenicity of the pancreas was compared with the liver and ribs and classified as grade 1, 2, and 3. The pregnancy outcomes of all participants were obtained from the hospital digital registration system.

RESULTS

The average fetal pancreatic circumference in the third trimester was 70.7 ± 0.6 mm (median, 70 [44-100.7]), with high intra-observer agreement (ICC 0.996 [0.995; 0.997]). A significant positive correlation was found between pancreatic circumference, body mass index (BMI), gestational age, and birth weight. Pancreatic measurements were significantly higher in composite adverse outcomes cases that included at least one of respiratory distress syndrome, hyperbilirubinemia, neonatal pneumonia, infection, and sepsis (p < 0.001). No relationship was found between pancreatic echogenicity and perinatal outcomes.

CONCLUSION

Fetal pancreas size was positively correlated with gestational age, BMI, and birth weight, and increased fetal pancreas size was associated with composite adverse neonatal outcomes.

Human Reproduction and Disturbed Genomic Imprinting

Genomic imprinting is a specific mode of gene regulation which particularly accounts for the factors involved in development. Its disturbance affects the fetus, the course of pregnancy and even the health of the mother. In children, aberrant imprinting signatures are associated with imprinting disorders (ImpDis). These alterations also affect the function of the placenta, which has consequences for the course of the pregnancy. The molecular causes of ImpDis comprise changes at the DNA level and methylation disturbances (imprinting defects/ImpDefs), and there is an increasing number of reports of both pathogenic fetal and maternal DNA variants causing ImpDefs. These ImpDefs can be inherited, but prediction of the pregnancy complications caused is difficult, as they can cause miscarriages, aneuploidies, health issues for the mother and ImpDis in the child. Due to the complexity of imprinting regulation, each pregnancy or patient with suspected altered genomic imprinting requires a specific workup to identify the precise molecular cause and also careful clinical documentation. This review will cover the current knowledge on the molecular causes of aberrant imprinting signatures and illustrate the need to identify this basis as the prerequisite for personalized genetic and reproductive counselling of families.

Imprinting disorders

Imprinting disorders (ImpDis) are congenital conditions that are characterized by disturbances of genomic imprinting. The most common individual ImpDis are Prader-Willi syndrome, Angelman syndrome and Beckwith-Wiedemann syndrome. Individual ImpDis have similar clinical features, such as growth disturbances and developmental delay, but the disorders are heterogeneous and the key clinical manifestations are often non-specific, rendering diagnosis difficult. Four types of genomic and imprinting defect (ImpDef) affecting differentially methylated regions (DMRs) can cause ImpDis. These defects affect the monoallelic and parent-of-origin-specific expression of imprinted genes. The regulation within DMRs as well as their functional consequences are mainly unknown, but functional cross-talk between imprinted genes and functional pathways has been identified, giving insight into the pathophysiology of ImpDefs. Treatment of ImpDis is symptomatic. Targeted therapies are lacking owing to the rarity of these disorders; however, personalized treatments are in development. Understanding the underlying mechanisms of ImpDis, and improving diagnosis and treatment of these disorders, requires a multidisciplinary approach with input from patient representatives.

Fetal Micro and Macroglossia: Defining Normal Fetal Tongue Size

OBJECTIVES

Abnormal fetal tongue size is a phenotypic feature of various syndromes including Beckwith-Wiedemann, Pierre-Robin, oromandibular limb hypoplasia, chromosomal aberrations, etc. Current data regarding normal fetal tongue size are limited. Hence, micro/macroglossia are subjectively determined. The aim of the study was to construct a contemporary fetal tongue nomogram and to assess its clinical contribution.

METHODS

A prospective cross-sectional study was performed in well dated, low risk, singleton pregnancies. Fetal tongues were measured by 5 trained sonographers. Highest quality images were selected. Intra- and interobserver variability was assessed. Tongue length, width, area, and circumference 1st to 99th centiles were calculated for each gestational week. Based on the normal tongue size charts, we created a Tongue Centile Calculator.

RESULTS

Over 18 months, 664 tongue measurements were performed. A cubic polynomial regression model best described the correlation between tongue size and gestational age. The correlation coefficient (r² ) was 0.934, 0.932, 0.925, and 0.953 for tongue length, width, area, and circumference, respectively (P < .001). Intra- and interobserver variability had high interclass correlation coefficients (>0.9). Using the new charts, we were able to identify 2 cases of macroglossia, subsequently diagnosed with Beckwith-Wiedemann, and 4 cases of microglossia, 3 associated with Pierre-Robin sequence, and 1 associated with persistent buccopharyngeal membrane.

CONCLUSIONS

We present novel fetal tongue size charts from 13 to 40 weeks of gestation. Clinical application of these nomograms may be beneficial in the prenatal diagnosis of syndromes or malformations associated with abnormal fetal tongue size.

Maternal Effect Mutations: A Novel Cause for Human Reproductive Failure

Genetic alterations significantly contribute to the aetiology of reproductive failure and comprise monogenic, chromosomal and epigenetic disturbances. The implementation of next-generation sequencing (NGS) based approaches in research and diagnostics allows the comprehensive analysis of these genetic causes, and the increasing detection rates of genetic mutations causing reproductive complications confirm the potential of the new techniques. Whereas mutations affecting the fetal genome are well known to affect pregnancies and their outcome, the contribution of alterations of the maternal genome was widely unclear. With the recent mainly NGS-based identification of maternal effect variants, a new cause of human reproductive failure has been identified. Maternal effect mutations affect the expression of subcortical maternal complex (SCMC) proteins from the maternal genome, and thereby disturb oocyte maturation and progression of the early embryo. They cause a broad range of reproductive failures and pregnancy complications, including infertility, miscarriages, hydatidiform moles, aneuploidies and imprinting disturbances in the fetus. The identification of women carrying these molecular alterations in SCMC encoding genes is therefore essential for a personalised reproductive and genetic counselling. The diagnostic application of new NGS-based assays allows the comprehensive analysis of these factors, and helps to further decipher these functional links between the factors and their disturbances. A close interdisciplinary collaboration between different disciplines is definitely required to further decipher the complex regulation of early embryo development, and to translate the basic research results into clinical practice.

Prenatal molecular testing and diagnosis of Beckwith-Wiedemann syndrome

OBJECTIVE

The objective of this study was to describe molecular findings and phenotypic features among individuals referred for prenatal Beckwith-Wiedemann syndrome (BWS) testing.

METHODS

Molecular diagnostic testing was performed using a sensitive quantitative real-time PCR-based assay capable of detecting mosaic methylation to the level of 3% at IC1 and IC2. Sanger sequencing of CDKN1C was performed in cases with normal methylation.

RESULTS

Of the 94 patients tested, a molecular diagnosis was identified for 25.5% of cases; 70.9% of diagnosed cases had loss of methylation at IC2, 4.2% had gain of methylation at IC1, 12.5% had paternal uniparental isodisomy, and 12.5% had CDKN1C loss-of-function variants. Methylation level changes in prenatal cases were significantly greater than changes identified in cases tested after birth. Cases with a prenatal molecular diagnosis had a significantly greater number of BWS-associated phenotypic features. The presence of either macroglossia or placentomegaly was most predictive of a BWS diagnosis.

CONCLUSION

Our results support the consensus statement advocating BWS molecular testing for all patients with one or more BWS-associated prenatal features and suggest that low-level mosaic methylation changes may be uncommon among prenatal BWS diagnoses.

Insights into the role of placenta thickness as a predictive marker of perinatal outcome

The placenta is a transitory organ indispensable for normal fetal maturation and growth. Recognition of abnormal placental variants is important in clinical practice, and a broader understanding of the significance of placental variants would help clinicians better manage affected pregnancies. Increased thickness of the placenta is reported to be a nonspecific finding but it is associated with many maternal and fetal abnormalities, including preeclampsia and abnormal fetal growth. In this review, we address the questions regarding the characteristics of placenta thickness and the relationship between thickened placenta and poor pregnancy outcomes.

New genetic and clinical evidence associated with fetal Beckwith-Wiedemann syndrome

Early detection of Beckwith-Wiedemann syndrome (BWS) is very important since it is very useful regarding counseling of parents concerning the risk of developing embryonic tumors, selection of the mode of delivery due to potential adrenal cysts that might bleed during labor, prevention of neonatal hypoglycemia and even options of pregnancy termination in non-viable fetuses. This report describes the prenatal classic sonographic triad of fetal BWS (omphalocele, macrosomia, macroglossia) and other supporting findings (hepatomegaly, adrenal enlargement) as well as additional postnatal evidence. Also, it demonstrates new molecular genetic evidence potentially associated with the disease (the presence of a novel heterozygous c.358G>T variant of the CDKN1C gene). Importantly, we provide new evidence indicating that elevated levels of the four serum biomarkers (alpha-fetoprotein, beta-human gonadotropin, unconjugated estriol, and inhibin-A) in late first or early second trimester might be strongly suggestive of BWS which may facilitate early detection especially in cases of no obvious anomaly. In conclusion, this study emphasizes on early detection of BWS as early as at 14 weeks of gestation, based on the abnormal rise of the four serum biomarkers together with omphalocele. To the best of our knowledge, this is the earliest prenatal detection of BWS ever reported. Finally, we provide new molecular genetic evidence that is, potentially associated with BWS.

Prenatal correction of IGF2 to rescue the growth phenotypes in mouse models of Beckwith-Wiedemann and Silver-Russell syndromes

Beckwith-Wiedemann syndrome (BWS) and Silver-Russell syndrome (SRS) are imprinting disorders manifesting as aberrant fetal growth and severe postnatal-growth-related complications. Based on the insulator model, one-third of BWS cases and two-thirds of SRS cases are consistent with misexpression of insulin-like growth factor 2 (IGF2), an important facilitator of fetal growth. We propose that the IGF2-dependent BWS and SRS cases can be identified by prenatal diagnosis and can be prevented by prenatal intervention targeting IGF2. We test this hypothesis using our mouse models of IGF2-dependent BWS and SRS. We find that genetically normalizing IGF2 levels in a double rescue experiment corrects the fetal overgrowth phenotype in the BWS model and the growth retardation in the SRS model. In addition, we pharmacologically rescue the BWS growth phenotype by reducing IGF2 signaling during late gestation. This animal study encourages clinical investigations to target IGF2 for prenatal diagnosis and prenatal prevention in human BWS and SRS.

Liao et al. use mouse models to test a prenatal approach for correcting growth anomalies in two imprinting diseases, BWS and SRS. They find that cases where the fetal growth factor IGF2 is misregulated can be diagnosed, and growth can be corrected by prenatally adjusting IGF2 or its signaling output.

Familial Beckwith-Wiedemann syndrome: Prenatal manifestation and a possible expansion of the phenotype

We describe a case of Beckwith-Wiedemann syndrome (BWS) demonstrating pre- and post-natal intra-familial variability. Our first encounter with the family occurred in the 1990s following the birth of 3 affected offspring. The first two pregnancies presented with exomphalos and elevated second trimester maternal serum alpha-fetoprotein (msAFP, 3.43 and 4.01 MOM, respectively) as well as elevated maternal human chorionic gonadotrophin (mhCG, 4.33 and 8.8 MOM, respectively). The diagnosis of BWS was confirmed postnatally in both cases. The third ongoing pregnancy presented only with elevated mhCG (7.09 MOM) and no malformation. Nonetheless BWS was suspected. The diagnosis was confirmed postnatally with clinical manifestations including macroglossia and cleft palate. Two affected female siblings were also diagnosed with Mullerian agenesis in adulthood. Suspecting a common genetic etiology, sequencing of the CDKN1C gene revealed a maternally inherited, likely pathogenic variant (NM_000076.2: c.367_385del; p.(Ala123Serfs*143)) causative of BWS. Chromosomal microarray and whole exome sequencing did not reveal any other pathogenic variant that would explain the Mullerian agenesis. One of the affected females underwent successful preimplantation genetic testing (PGT) with a surrogate and gave birth to a healthy female. To the best of our knowledge, this is the first report of Mullerian agenesis as a possible rare expansion of the BWS phenotype. In addition, this case highlights the potential role of abnormal second trimester biochemical markers (msAFP, mHCG) as possible indicators of BWS, especially in familial cases.

Prenatal Detection of Uniparental Disomies (UPD): Intended and Incidental Finding in the Era of Next Generation Genomics

Prenatal detection of uniparental disomy (UPD) is a methodological challenge, and a positive testing result requires comprehensive considerations on the clinical consequences as well as ethical issues. Whereas prenatal testing for UPD in families which are prone to UPD formation (e.g., in case of chromosomal variants, imprinting disorders) is often embedded in genetic counselling, the incidental identification of UPD is often more difficult to manage. With the increasing application of high-resolution test systems enabling the identification of UPD, an increase in pregnancies with incidental detection of UPD can be expected. This paper will cover the current knowledge on uniparental disomies, their clinical consequences with focus on prenatal testing, genetic aspects and predispositions, genetic counselling, as well as methods (conventional tests and high-throughput assays).

Prenatal features in Beckwith-Wiedemann syndrome and indications for prenatal testing

BACKGROUND

Most cases of Beckwith-Wiedemann spectrum (BWSp) are diagnosed after birth and few studies evaluated the prenatal phenotype; here, we investigate these aspects in a large series of patients with BWSp.

METHODS

Eighty-nine patients with BWSp recruited through the BWSp Internal Registry of the Pediatric Genetics Unit of the Regina Margherita Children's Hospital of Torino and through the Italian Association of Patients with BWSp. Data collection was conducted through administration of a personalised questionnaire, interview to patients' parents, review of the clinical records, including prenatal ultrasound (US) and biochemical screening tests, physical examination and review of clinical and molecular data of the patients.

RESULTS

Seventeen patients (19.1%) were conceived through assisted reproductive techniques (ART). Twinning occurred in nine pregnancies (three from ART). Pregnancy biochemical screening tests showed increased alpha-fetoprotein (1.52±0.79 multiples of median (MoM), p=0.001), uEstriol (1.37±0.38 MoM, p<0.001) and total human chorionic gonadotrophin (2.14±2.12 MoM, p=0.008) at 15-18 weeks (n=28). Morphology US scan revealed abdominal and head circumferences higher than normal (1.42±1.10 SD scores, p<0.001 and 0.54±0.88, p<0.001, respectively) with normal femur lengths. Sixty-four cases (71.9%%) had a various combination of US findings, including macrosomia (n=32), omphalocele (n=15), enlargement of abdominal organs (n=6), macroglossia (n=11), adrenal cysts/masses (n=2), nephroureteral anomalies (n=11), polyhydramnios (n=28), placental enlargement (n=2) or mesenchymal dysplasia (n=4).

CONCLUSION

We propose a clinical scoring system for prenatal molecular investigations defining major, minor and supportive criteria among the several features often observed prenatally in BWSp.

Preclinical and Clinical Epigenetic-Based Reconsideration of Beckwith-Wiedemann Syndrome

Epigenetics has achieved a profound impact in the biomedical field, providing new experimental opportunities and innovative therapeutic strategies to face a plethora of diseases. In the rare diseases scenario, Beckwith-Wiedemann syndrome (BWS) is a pediatric pathological condition characterized by a complex molecular basis, showing alterations in the expression of different growth-regulating genes. The molecular origin of BWS is associated with impairments in the genomic imprinting of two domains at the 11p15.5 chromosomal region. The first domain contains three different regions: insulin growth like factor gene (IGF2), H19, and abnormally methylated DMR1 region. The second domain consists of cell proliferation and regulating-genes such as CDKN1C gene encoding for cyclin kinase inhibitor its role is to block cell proliferation. Although most cases are sporadic, about 5-10% of BWS patients have inheritance characteristics. In the 11p15.5 region, some of the patients have maternal chromosomal rearrangements while others have Uniparental Paternal Disomy UPD(11)pat. Defects in DNA methylation cause alteration of genes and the genomic structure equilibrium leading uncontrolled cell proliferation, which is a typical tumorigenesis event. Indeed, in BWS patients an increased childhood tumor predisposition is observed. Here, we summarize the latest knowledge on BWS and focus on the impact of epigenetic alterations to an increased cancer risk development and to metabolic disorders. Moreover, we highlight the correlation between assisted reproductive technologies and this rare disease. We also discuss intriguing aspects of BWS in twinning. Epigenetic therapies in clinical trials have already demonstrated effectiveness in oncological and non-oncological diseases. In this review, we propose a potential "epigenetic-based" approaches may unveil new therapeutic options for BWS patients. Although the complexity of the syndrome is high, patients can be able to lead a normal life but tumor predispositions might impair life expectancy. In this sense epigenetic therapies should have a supporting role in order to guarantee a good prognosis.

Disturbed genomic imprinting and its relevance for human reproduction: causes and clinical consequences

BACKGROUND

Human reproductive issues affecting fetal and maternal health are caused by numerous exogenous and endogenous factors, of which the latter undoubtedly include genetic changes. Pathogenic variants in either maternal or offspring DNA are associated with effects on the offspring including clinical disorders and nonviable outcomes. Conversely, both fetal and maternal factors can affect maternal health during pregnancy. Recently, it has become evident that mammalian reproduction is influenced by genomic imprinting, an epigenetic phenomenon that regulates the expression of genes according to their parent from whom they are inherited. About 1% of human genes are normally expressed from only the maternally or paternally inherited gene copy. Since numerous imprinted genes are involved in (embryonic) growth and development, disturbance of their balanced expression can adversely affect these processes.

OBJECTIVE AND RATIONALE

This review summarises current our understanding of genomic imprinting in relation to human ontogenesis and pregnancy and its relevance for reproductive medicine.

SEARCH METHODS

Literature databases (Pubmed, Medline) were thoroughly searched for the role of imprinting in human reproductive failure. In particular, the terms ‘multilocus imprinting disturbances, SCMC, NLRP/NALP, imprinting and reproduction’ were used in various combinations.

OUTCOMES

A range of molecular changes to specific groups of imprinted genes are associated with imprinting disorders, i.e. syndromes with recognisable clinical features including distinctive prenatal features. Whereas the majority of affected individuals exhibit alterations at single imprinted loci, some have multi-locus imprinting disturbances (MLID) with less predictable clinical features. Imprinting disturbances are also seen in some nonviable pregnancy outcomes, such as (recurrent) hydatidiform moles, which can therefore be regarded as a severe form of imprinting disorders. There is growing evidence that MLID can be caused by variants in the maternal genome altering the imprinting status of the oocyte and the embryo, i.e. maternal effect mutations. Pregnancies of women carrying maternal affect mutations can have different courses, ranging from miscarriages to birth of children with clinical features of various imprinting disorders.

WIDER IMPLICATIONS

Increasing understanding of imprinting disturbances and their clinical consequences have significant impacts on diagnostics, counselling and management in the context of human reproduction. Defining criteria for identifying pregnancies complicated by imprinting disorders facilitates early diagnosis and personalised management of both the mother and offspring. Identifying the molecular lesions underlying imprinting disturbances (e.g. maternal effect mutations) allows targeted counselling of the family and focused medical care in further pregnancies.

Overgrowth syndromes - clinical and molecular aspects and tumour risk

Overgrowth syndromes are a heterogeneous group of rare disorders characterized by generalized or segmental excessive growth commonly associated with additional features, such as visceromegaly, macrocephaly and a large range of various symptoms. These syndromes are caused by either genetic or epigenetic anomalies affecting factors involved in cell proliferation and/or the regulation of epigenetic markers. Some of these conditions are associated with neurological anomalies, such as cognitive impairment or autism. Overgrowth syndromes are frequently associated with an increased risk of cancer (embryonic tumours during infancy or carcinomas during adulthood), but with a highly variable prevalence. Given this risk, syndrome-specific tumour screening protocols have recently been established for some of these conditions. Certain specific clinical traits make it possible to discriminate between different syndromes and orient molecular explorations to determine which molecular tests to conduct, despite the syndromes having overlapping clinical features. Recent advances in molecular techniques using next-generation sequencing approaches have increased the number of patients with an identified molecular defect (especially patients with segmental overgrowth). This Review discusses the clinical and molecular diagnosis, tumour risk and recommendations for tumour screening for the most prevalent generalized and segmental overgrowth syndromes.

Prenatal imaging throughout gestation in Beckwith-Wiedemann syndrome

PURPOSE

Prenatal occurrence and timing of appearance of associated features in Beckwith-Wiedemann syndrome (BWS) are unknown. We reviewed our BWS patients with serial fetal imaging and correlated these with postnatal findings.

METHODS

All BWS patients with fetal ultrasound (US) or magnetic resonance imaging (MRI) from 2000 to 2016 were reviewed to determine the presence of polyhydramnios, placentamegaly, macrosomia, macroglossia, retrognathia, omphalocele, visceromegaly, and hemihypertrophy. These observations were correlated with postnatal findings. Data were analyzed by Mann-Whitney U test.

RESULTS

Nine BWS patients underwent 42 fetal imaging studies with median of five (range of two to six) studies per patient between 13 and 35 weeks gestation. All prenatal findings were confirmed postnatally with complete concordance. All patients with omphalocele were detected early in gestation but other postnatal findings less predictably so. All omphaloceles were small, and were found significantly earlier in gestation than macrosomia (P = 0.004) and macroglossia (P = 0.012). Visceromegaly and retrognathia were less frequent, with no significant differences in median gestational age from omphalocele when prenatally identified.

CONCLUSIONS

In BWS, omphalocele is the most common prenatal finding and routinely observed in early gestation with 100% accuracy. Associated findings of macrosomia, macroglossia, visceromegaly, and retrognathia, when present, are detected later in gestation. Imaging in later gestation may reveal additional abnormalities that support a BWS diagnosis.

Diagnosis and Management of Beckwith-Wiedemann Syndrome

Beckwith-Wiedemann syndrome (BWS) is a human genomic imprinting disorder that presents with a wide spectrum of clinical features including overgrowth, abdominal wall defects, macroglossia, neonatal hypoglycemia, and predisposition to embryonal tumors. It is associated with genetic and epigenetic changes on the chromosome 11p15 region, which includes two imprinting control regions. Here we review strategies for diagnosing and managing BWS and delineate commonly used genetic tests to establish a molecular diagnosis of BWS. Recommended first-line testing assesses DNA methylation and copy number variation of the BWS region. Tissue mosaicism can occur in patients with BWS, posing a challenge for genetic testing, and a negative test result does not exclude a diagnosis of BWS. Further testing should analyze additional tissue samples or employ techniques with higher diagnostic yield. Identifying the BWS molecular subtype is valuable for coordinating patient care because of the (epi)genotype-phenotype correlations, including different risks and types of embryonal tumors.

Beckwith Wiedemann syndrome: A population-based study on prevalence, prenatal diagnosis, associated anomalies and survival in Europe

Beckwith Wiedemann syndrome is a complex developmental disorder characterized by somatic overgrowth, macroglossia, abdominal wall defects, neonatal hypoglycemia, and predisposition to embryonal tumors. We present epidemiological and clinical aspects of patients with Beckwith Wiedemann syndrome diagnosed prenatally or in the early years of life, using data from EUROCAT (European Surveillance of Congenital Anomalies) registries. The study population consisted of 371 cases identified between January 1990 and December 2015 in 34 registries from 16 European countries. There were 15 (4.0%) terminations of pregnancy after prenatal detection of severe anomaly/anomalies, 10 fetal deaths (2.7%), and 346 (93.3%) live-births. Twelve (3.6%) of the 330 live-births with available information on survival died in the first week of life, of those eleven (91.6%) were preterm. First-year survival rate was 90.9%. Prematurity was present in 40.6% of males and 33.9% of females. Macrosomia was found in 49.2% and 43.3% of preterm males and females, respectively. Of term newborns, 41.1% of males and 24% of females were macrosomic. Out of 353 cases with known time of diagnosis, 39.9% were suspected prenatally, 36.3% at birth, 7.6% were diagnosed in the first week of life, and 16.2% in the first year of life. The mean gestational age at prenatal diagnosis by obstetric ultrasound was 19.8 ± 6.2 (11-39) gestational weeks. The mean prenatal diagnosis of cases where parents opted for termination of pregnancy was 15.3 ± 2.4 (11-22) gestational weeks, and the mean gestational age at termination was 19.3 ± 4.1 (13-26) gestational weeks. The prenatal detection rate was 64.1% (141/220) with no significant change over time. There were 12.7% of familial cases. The study confirmed the association of assisted reproductive technologies with Beckwith Wiedemann syndrome, as 7.2% (13/181) of patients were conceived by one of the methods of assisted reproductive technologies, which was three times higher compared to the general population of the countries included in the study. Twin pregnancies of undetermined zygosity were recorded in 5.7% (21/365) cases, and were on average three to four times more common than in European countries that participated in the study. The estimated mean prevalence of classical Beckwith Wiedemann syndrome in Europe was 3.8 per 100,000 births or 1:26,000 births.

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.

NLRP genes and their role in preeclampsia and multi-locus imprinting disorders

Preeclampsia (PE) affects 2-5% of all pregnancies. It is a multifactorial disease, but it has been estimated that 35% of the variance in liability of PE are attributable to maternal genetic effects and 20% to fetal genetic effects. PE has also been reported in women delivering children with Beckwith-Wiedemann syndrome (BWS, OMIM 130650), a disorder associated with aberrant methylation at genomically imprinted loci. Among others, members of the NLRP gene family are involved in the etiology of imprinting defects. Thus, a functional link between PE, NLRP gene mutations and aberrant imprinting can be assumed. Therefore we analyzed a cohort of 47 PE patients for NLRP gene mutations by next generation sequencing. In 25 fetuses where DNA was available we determined the methylation status at the imprinted locus. With the exception of one woman heterozygous for a missense variant in the NLRP7 gene (NM_001127255.1(NLRP7):c.542G>C) we could not identify further carriers, in the fetal DNA normal methylation patterns were observed. Thus, our negative screening results in a well-defined cohort indicate that NLRP mutations are not a relevant cause of PE, though strong evidence for a functional link between NLRP mutations, PE and aberrant methylation exist.

The Normal Fetal Pancreas

OBJECTIVES

The aim of the study was to assess the sonographic feasibility of measuring the fetal pancreas and its normal development throughout pregnancy.

METHODS

We conducted a cross-sectional prospective study between 19 and 36 weeks' gestation. The study included singleton pregnancies with normal pregnancy follow-up. The pancreas circumference was measured. The first 90 cases were tested to assess feasibility.

RESULTS

Two hundred ninety-seven fetuses of nondiabetic mothers were recruited during a 3-year period. The overall satisfactory visualization rate was 61.6%. The intraobserver and interobserver variability had high interclass correlation coefficients of of 0.964 and 0.967, respectively. A cubic polynomial regression described best the correlation of pancreas circumference with gestational age (r = 0.744; P < .001) and significant correlations also with abdominal circumference and estimated fetal weight (Pearson r = 0.829 and 0.812, respectively; P < .001). Modeled pancreas circumference percentiles for each week of gestation were calculated. During the study period, we detected 2 cases with overgrowth syndrome and 1 case with an annular pancreas.

CONCLUSIONS

In this study, we assessed the feasibility of sonography for measuring the fetal pancreas and established a normal reference range for the fetal pancreas circumference throughout pregnancy. This database can be helpful when investigating fetomaternal disorders that can involve its normal development.

Prenatal molecular testing for Beckwith-Wiedemann and Silver-Russell syndromes: a challenge for molecular analysis and genetic counseling

Beckwith-Wiedemann and Silver-Russell syndromes (BWS/SRS) are two imprinting disorders (IDs) associated with disturbances of the 11p15.5 chromosomal region. In BWS, epimutations and genomic alterations within 11p15.5 are observed in >70% of patients, whereas in SRS they are observed in about 60% of the cases. In addition, 10% of the SRS patients carry a maternal uniparental disomy of chromosome 7 11p15.5. There is an increasing demand for prenatal testing of these disorders owing to family history, indicative prenatal ultrasound findings or aberrations involving chromosomes 7 and 11. The complex molecular findings underlying these disorders are a challenge not only for laboratories offering these tests but also for geneticists counseling affected families. The scope of counseling must consider the range of detectable disturbances and their origin, the lack of precise quantitative knowledge concerning the inheritance and recurrence risks for the epigenetic abnormalities, which are hallmarks of these developmental disorders. In this paper, experts in the field of BWS and SRS, including members of the European network of congenital IDs (EUCID.net; www.imprinting-disorders.eu), put together their experience and work in the field of 11p15.5-associated IDs with a focus on prenatal testing. Altogether, prenatal tests of 160 fetuses (122 referred for BWS, 38 for SRS testing) from 5 centers were analyzed and reviewed. We summarize the current knowledge on BWS and SRS with respect to diagnostic testing, the consequences for prenatal genetic testing and counseling and our cumulative experience in dealing with these disorders.

Fetal growth patterns in Beckwith-Wiedemann syndrome

We provide data on fetal growth pattern on the molecular subtypes of Beckwith-Wiedemann syndrome (BWS): IC1 gain of methylation (IC1-GoM), IC2 loss of methylation (IC2-LoM), 11p15.5 paternal uniparental disomy (UPD), and CDKN1C mutation. In this observational study, gestational ages and neonatal growth parameters of 247 BWS patients were compared by calculating gestational age-corrected standard deviation scores (SDS) and proportionality indexes to search for differences among IC1-GoM (n = 21), UPD (n = 87), IC2-LoM (n = 147), and CDKN1C mutation (n = 11) patients. In IC1-GoM subgroup, weight and length are higher than in other subgroups. Body proportionality indexes display the following pattern: highest in IC1-GoM patients, lowest in IC2-LoM/CDKN1C patients, intermediate in UPD ones. Prematurity was significantly more prevalent in the CDKN1C (64%) and IC2-LoM subgroups (37%). Fetal growth patterns are different in the four molecular subtypes of BWS and remarkably consistent with altered gene expression primed by the respective molecular mechanisms. IC1-GoM cases show extreme macrosomia and severe disproportion between weight and length excess. In IC2-LoM/CDKN1C patients, macrosomia is less common and associated with more proportionate weight/length ratios with excess of preterm birth. UPD patients show growth patterns closer to those of IC2-LoM, but manifest a body mass disproportion rather similar to that seen in IC1-GoM cases.

Diagnosis and Management of Hereditary Adrenal Cancer

Benign adrenocortical tumours (ACT) are relatively frequent lesions; on the contrary, adrenocortical carcinoma (ACC) is a rare and aggressive malignancy with unfavourable prognosis. Recent advances in the molecular understanding of adrenal cancer offer promise for better therapies in the future. Many of these advances stem from the molecular elucidation of genetic conditions predisposing to the development of ACC. Six main clinical syndromes have been described to be associated with hereditary adrenal cancer. In these conditions, genetic counselling plays an important role for the early detection and follow-up of the patients and the affected family members.

Recommendations of the Scientific Committee of the Italian Beckwith-Wiedemann Syndrome Association on the diagnosis, management and follow-up of the syndrome

Beckwith-Wiedemann syndrome (BWS) is the most common (epi)genetic overgrowth-cancer predisposition disorder. Given the absence of consensual recommendations or international guidelines, the Scientific Committee of the Italian BWS Association (www.aibws.org) proposed these recommendations for the diagnosis, molecular testing, clinical management, follow-up and tumor surveillance of patients with BWS. The recommendations are intended to allow a timely and appropriate diagnosis of the disorder, to assist patients and their families, to provide clinicians and caregivers optimal strategies for an adequate and satisfactory care, aiming also at standardizing clinical practice as a national uniform approach. They also highlight the direction of future research studies in this setting. With recent advances in understanding the disease (epi)genetic mechanisms and in describing large cohorts of BWS patients, the natural history of the disease will be dissected. In the era of personalized medicine, the emergence of specific (epi)genotype-phenotype correlations in BWS will likely lead to differentiated follow-up approaches for the molecular subgroups, to the development of novel tools to evaluate the likelihood of cancer development and to the refinement and optimization of current tumor screening strategies.

CONCLUSIONS

In this article, we provide the first comprehensive recommendations on the complex management of patients with Beckwith-Wiedemann syndrome.