Phenotype of genetically confirmed Silver-Russell syndrome beyond childhood

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.

Case report: atypical Silver-Russell syndrome patient with hand dystonia: the valuable support of the consensus statement to the wide syndromic spectrum

The amount of Insulin Growth Factor 2 (IGF2) controls the rate of embryonal and postnatal growth. The IGF2 and adjacent H19 are the imprinted genes of the telomeric cluster in the 11p15 chromosomal region regulated by differentially methylated regions (DMRs) or imprinting centers (ICs): H19/IGF2:IG-DMR (IC1). Dysregulation due to IC1 Loss-of-Methylation (LoM) or Gain-of-Methyaltion (GoM) causes Silver-Russell syndrome (SRS) or Beckwith-Wiedemann syndrome (BWS) disorders associated with growth retardation or overgrowth, respectively. Specific features define each of the two syndromes, but isolated asymmetry is a common cardinal feature, which is considered sufficient for a diagnosis in the BWS spectrum. Here, we report the case of a girl with right body asymmetry, which suggested BWS spectrum. Later, BWS/SRS molecular analysis identified IC1_LoM revealing the discrepant diagnosis of SRS. A clinical re-evaluation identified a relative macrocephaly and previously unidentified growth rate at lower limits of normal at birth, feeding difficulties, and asymmetry. Interestingly, and never previously described in IC1_LoM SRS patients, since the age of 16, she has developed hand-writer's cramps, depression, and bipolar disorder. Trio-WES identified a VPS16 heterozygous variant [NM_022575.4:c.2185C>G:p.Leu729Val] inherited from her healthy mother. VPS16 is involved in the endolysosomal system, and its dysregulation is linked to autosomal dominant dystonia with incomplete penetrance and variable expressivity. IGF2 involvement in the lysosomal pathway led us to speculate that the neurological phenotype of the proband might be triggered by the concurrent IGF2 deficit and VPS16 alteration.

Fetal manipulation of maternal metabolism is a critical function of the imprinted Igf2 gene

Maternal-offspring interactions in mammals involve both cooperation and conflict. The fetus has evolved ways to manipulate maternal physiology to enhance placental nutrient transfer, but the mechanisms involved remain unclear. The imprinted Igf2 gene is highly expressed in murine placental endocrine cells. Here, we show that Igf2 deletion in these cells impairs placental endocrine signaling to the mother, without affecting placental morphology. Igf2 controls placental hormone production, including prolactins, and is crucial to establish pregnancy-related insulin resistance and to partition nutrients to the fetus. Consequently, fetuses lacking placental endocrine Igf2 are growth restricted and hypoglycemic. Mechanistically, Igf2 controls protein synthesis and cellular energy homeostasis, actions dependent on the placental endocrine cell type. Igf2 loss also has additional long-lasting effects on offspring metabolism in adulthood. Our study provides compelling evidence for an intrinsic fetal manipulation system operating in placenta that modifies maternal metabolism and fetal resource allocation, with long-term consequences for offspring metabolic health.

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.

Dyke-Davidoff-Masson Syndrome: A Case Report

Dyke-Davidoff-Masson syndrome (DDMS) is a rare neurological entity that is predominantly seen in childhood. Here, we present the case of a 13-year-old girl who was brought to the pediatric ward for general examination with a previous history of seizures, speech difficulty, facial deviation, and progressive left-sided hemiparesis that started at the age of two, followed by delayed developmental milestones. Computed tomography (CT) and magnetic resonance imaging (MRI) of the brain showed right cerebral hemiatrophy, ventriculomegaly, hyperpneumatization of the sinus, the decreased caliber of cortical veins, and skull thickening on the right were all characteristic findings of DDMS. Based on the history, clinical presentation, and imaging findings from CT and MRI, DDMS was confirmed. Identifying DDMS in a clinical setting can be challenging because of low awareness of the condition and varied clinical presentations. Although CT and MRI imaging are the gold standards in diagnosing DDMS, the early manifestations of the disease cannot be well-appreciated on a CT and would likely require an MRI. Since there is no standardized protocol for managing DDMS, the treatment is primarily symptomatic. Early identification and diagnosis of the syndrome are essential to aid the child's mental and physical development through a multidisciplinary approach. There is also a need to improve awareness of DDMS so that the condition can be considered a potential differential diagnosis amongst other similar conditions and does not get misdiagnosed. The lack of a proper protocol for the management of DDMS prompts more research for a better understanding and early identification of the condition.

Facilitating the transition from paediatric to adult care in endocrinology: a focus on growth disorders

PURPOSE OF REVIEW

Many childhood-onset growth disorders (COGDs) require continued care into adulthood, and the time of transition between paediatric and adult providers carries a high risk for interruptions in medical care and consequent worsening of disease management.

RECENT FINDINGS

Research into best practices for healthcare transition (HCT) describes three distinct stages. Stage 1, transition planning and preparation, begins in the paediatric setting during early adolescence and ensures that the patient has adequate medical knowledge, self-management skills, and readiness for transition. Stage 2, transfer to adult care, occurs with variable timing depending on transition readiness and is best facilitated by warm hand-offs and, when possible, joint visits with the paediatric and adult provider(s) and/or involvement of a care coordinator. Stage 3, intake and integration into adult care, entails retaining the patient in the adult setting, ideally through the involvement of a multidisciplinary approach.

SUMMARY

This review covers general principles for ensuring smooth transition of adolescents and young adults (AYA) with COGD, disease-specific medical considerations for paediatric and adult endocrinologists during the transition process, and general and disease-specific resources to assess transition readiness and facilitate transition.

Executive functioning in adolescents and adults with Silver-Russell syndrome

Silver-Russell syndrome (SRS) is a rare imprinting disorder characterized by prenatal and postnatal growth retardation. The two principal causes of SRS are loss of methylation on chromosome 11p15 (11p15 LOM) and maternal uniparental disomy of chromosome 7 (UPD(7)mat). Knowledge of the neuropsychological profile of SRS remains sparse and incomplete even if several difficulties related to attention and learning have been reported both in the literature and by patients with SRS. These difficulties could be the result of troubles in different cognitive domains, but also of executive dysfunction. Nevertheless, executive functioning has never been investigated, even though executive functions play an essential role in psychological development, and are extensively involved in daily life. The present study explored the executive functioning of individuals with SRS due to UPD(7)mat or 11p15 LOM. A battery of executive tasks assessing cognitive flexibility, inhibitory control, and working memory, together with a task assessing sustained attention, was administered to 19 individuals with SRS (13-39 years) and 19 healthy controls. The Behavior Rating Inventory of Executive Function was also completed by the participants' families. The results showed that participants with SRS had similar performance (z-scores) to our controls, in a context of normal intellectual efficiency. Group comparisons with Bayesian statistics showed a single difference between the 11p15 LOM and control groups: the completion time for part A of the Trail Making Test appeared to be longer in the 11p15 LOM group than in the control group. However, at the clinical level, several participants with SRS had clinically significant scores on various measures of EFs. Thus, the cognitive phenotype of SRS did not appear to be characterized by executive dysfunction, but individuals with SRS could be at high risk of developing executive dysfunction or attention-deficit/hyperactivity disorder. These results provide new insights into the neuropsychological profile of individuals with SRS.

Height and body mass index in molecularly confirmed Silver-Russell syndrome and the long-term effects of growth hormone treatment

OBJECTIVE

Silver-Russell syndrome (SRS) causes short stature. Growth hormone (GH) treatment aims to increase adult height. However, data are limited on the long-term outcomes of GH in patients with molecularly confirmed SRS. This study evaluated height, body mass index (BMI) and GH treatment in molecularly confirmed SRS.

DESIGN

An observational study with retrospective data collection.

PATIENTS

Individuals with molecularly confirmed SRS aged ≥13 years.

MEASUREMENTS

Data were collected on height, height gain (change in height standard deviation score [SDS] from childhood to final or near-final height), BMI and gain in BMI (from childhood to adulthood) and previous GH treatment.

RESULTS

Seventy-one individuals (40 female) were included. The median age was 22.0 years (range 13.2-69.7). The molecular diagnoses: H19/IGF2:IG-DMR LOM in 80.3% (57/71); upd(7)mat in 16.9% (12/71) and IGF2 mutation in 2.8% (2/71). GH treatment occurred in 77.5% (55/71). Total height gain was greater in GH-treated individuals (median 1.53 SDS vs. 0.53 SDS, p = .007), who were shorter at treatment initiation (-3.46 SDS vs. -2.91 SDS, p = .04) but reached comparable heights to GH-untreated individuals (-2.22 SDS vs. -2.74 SDS, p = .7). In GH-treated individuals, BMI SDS was lower at the most recent assessment (median -1.10 vs. 1.66, p = .002) with lower BMI gain (2.01 vs. 3.58, p = .006) despite similar early BMI SDS to GH-untreated individuals (median -2.65 vs. -2.78, p = .3).

CONCLUSIONS

These results support the use of GH in SRS for increasing height SDS. GH treatment was associated with lower adult BMI which may reflect improved metabolic health even following discontinuation of therapy.

IGF2: Development, Genetic and Epigenetic Abnormalities

In the 30 years since the first report of parental imprinting in insulin-like growth factor 2 (Igf2) knockout mouse models, we have learnt much about the structure of this protein, its role and regulation. Indeed, many animal and human studies involving innovative techniques have shed light on the complex regulation of IGF2 expression. The physiological roles of IGF-II have also been documented, revealing pleiotropic tissue-specific and developmental-stage-dependent action. Furthermore, in recent years, animal studies have highlighted important interspecies differences in IGF-II function, gene expression and regulation. The identification of human disorders due to impaired IGF2 gene expression has also helped to elucidate the major role of IGF-II in growth and in tumor proliferation. The Silver-Russell and Beckwith-Wiedemann syndromes are the most representative imprinted disorders, as they constitute both phenotypic and molecular mirrors of IGF2-linked abnormalities. The characterization of patients with either epigenetic or genetic defects altering IGF2 expression has confirmed the central role of IGF-II in human growth regulation, particularly before birth, and its effects on broader body functions, such as metabolism or tumor susceptibility. Given the long-term health impact of these rare disorders, it is important to understand the consequences of IGF2 defects in these patients.

Ongoing Challenges in the Diagnosis of 11p15.5-Associated Imprinting Disorders

The overgrowth disorder Beckwith-Wiedemann syndrome and the growth restriction disorder Silver-Russell syndrome have been described as 'mirror' syndromes, in both their clinical features and molecular causes. Clinically, their nonspecific features, focused around continuous variables of atypical growth, make it hard to set diagnostic thresholds that are pragmatic without potentially excluding some cases. Molecularly, both are imprinting disorders, classically associated with 'opposite' genetic and epigenetic changes to genes on chromosome 11p15, but both are associated with somatic mosaicism as well as an increasing range of alternative (epi)genetic changes to other genes, which make molecular diagnosis an increasingly complex process. In this Current Opinion, we explore how the understanding of Beckwith-Wiedemann syndrome and Silver-Russell syndrome has evolved in recent years, stretching the canonical 'mirror' designations in different ways for the two disorders and how this is changing clinical and molecular diagnosis. We suggest some possible directions of travel toward more timely and stratified diagnosis, so that patients can access the early interventions that are so critical for good outcome.

Quality of life and mental health of adolescents and adults with Silver-Russell syndrome

Silver-Russell syndrome (SRS) is a rare imprinting disorder characterized by prenatal and postnatal growth retardation. Despite normal intellectual functioning, psychosocial and behavioral difficulties have been observed in this syndrome. However, few studies have dealt with these aspects, even though this could enhance the current understanding of the SRS and, more importantly, improve the management of potential psychosocial problems. Given the sparse literature, this cross-sectional study aimed to establish the psychosocial and behavioral profile of individuals with SRS. To this end, we assessed the quality of life (World Health Organization Quality of Life Questionnaire-Short Form), self-esteem (Coopersmith's Self-Esteem Inventory), anxiety (Spielberger's State-Trait Anxiety Inventory), and behavioral and emotional problems (Child Behavior Checklist and Adult Behavior Checklist) in a sample of 19 adults and adolescents with SRS and 18 without SRS (controls). We also analyzed clinical features, molecular genetic diagnosis, and past or current treatments of participants with SRS. Based on prior studies, we expected to observe psychological and behavioral difficulties in our clinical population. We also expected these difficulties, shared by both adolescents and adults with SRS, to be associated with factors such as height, genetics, or treatment. Overall, our results showed that participants with SRS had similar performances to those of controls, despite high interindividual variability among the adults with SRS. For example, while adults with SRS had a similar mean total self-esteem score to control participants, 45% of the adults with SRS still had very low self-esteem. In addition, adolescents and adults with SRS did not necessarily have the same difficulties. Social and behavioral problems appeared to be more common in adolescents with upd(7)mat while in adults, difficulties were not associated with either height, weight, NH-CSS score, or GH treatment but did appear to be associated with GnRHa treatment. Indeed, low self-esteem was associated with GnRHa treatment. Overall, this study shows that early intervention and multidisciplinary care right up to adulthood, including psychological support, are needed for this population, regardless of the molecular abnormality responsible for SRS, to cope with potential psychosocial problems.

Experiences of adolescents living with Silver-Russell syndrome

OBJECTIVE

The psychosocial impact of growing up with Silver-Russell syndrome (SRS), characterised by growth failure and short stature in adulthood, has been explored in adults; however, there are no accounts of contemporary lived experience in adolescents. Such data could inform current healthcare guidance and transition to adult services. We aimed to explore the lived experience of adolescents with SRS.

DESIGN/SETTING/PATIENTS

In-depth, semi-structured interviews were conducted between January 2015 and October 2016 with a sample of eight adolescents aged 13-18 (five girls) with genetically confirmed SRS from the UK. Qualitative interviews were transcribed and coded to identify similarities and differences using thematic analysis; codes were then grouped to form overarching themes.

RESULTS

We identified four themes from the interview data: (1) the psychosocial challenges of feeling and looking different; (2) pain, disability and fatigue; (3) anticipated stigma; and (4) building resilience and acceptance. Despite adolescents accepting SRS in their lives, they described ongoing psychosocial challenges and anticipated greater problems to come, such as stigma from prospective employers.

CONCLUSIONS

Adolescents with SRS may experience psychosocial difficulties from as young as 10 years old related to feeling and looking different; pain, disability and fatigue; anticipated stigma; and future challenges around employment. We discuss these findings in relation to recommendations for the care of adolescents with SRS to prepare them for adult life.

Segmental maternal uniparental disomy of chromosome 7q in a patient with congenital chloride diarrhea

Background

The main symptoms of congenital chloride diarrhea (CCD) main symptoms are watery diarrhea, hypochloremia, and hypokalemic metabolic alkalosis. Silver–Russell syndrome (SRS) is a heterogeneous imprinting disorder characterized by severe intrauterine retardation, poor postnatal growth, and facial dysmorphism.

Methods

Parent‐offspring trio whole‐exome sequencing was used to identify the causal variants. Sequencing reads were mapped to the reference of human genome version hg19. Sanger sequencing was performed as a confirmatory experiment.

Results

The proband was a patient with SRS caused by maternal uniparental disomy 7. The CCD of the proband was caused by homozygous variant c.1515–1 (IVS13) G>A; both mutated alleles were inherited from her mother.

Conclusion

We report the first clinical case of CCD and SRS occurring together. Patients with milder phenotypes may be difficult to diagnose in early stage, but close monitoring of potential complications is important for identification.

Growth Restriction and Genomic Imprinting-Overlapping Phenotypes Support the Concept of an Imprinting Network

Intrauterine and postnatal growth disturbances are major clinical features of imprinting disorders, a molecularly defined group of congenital syndromes caused by molecular alterations affecting parentally imprinted genes. These genes are expressed monoallelically and in a parent-of-origin manner, and they have an impact on human growth and development. In fact, several genes with an exclusive expression from the paternal allele have been shown to promote foetal growth, whereas maternally expressed genes suppress it. The evolution of this correlation might be explained by the different interests of the maternal and paternal genomes, aiming for the conservation of maternal resources for multiple offspring versus extracting maximal maternal resources. Since not all imprinted genes in higher mammals show the same imprinting pattern in different species, the findings from animal models are not always transferable to human. Therefore, human imprinting disorders might serve as models to understand the complex regulation and interaction of imprinted loci. This knowledge is a prerequisite for the development of precise diagnostic tools and therapeutic strategies for patients affected by imprinting disorders. In this review we will specifically overview the current knowledge on imprinting disorders associated with growth retardation, and its increasing relevance in a personalised medicine direction and the need for a multidisciplinary therapeutic approach.

Need for a precise molecular diagnosis in Beckwith-Wiedemann and Silver-Russell syndrome: what has to be considered and why it is important

Abstract

Molecular diagnostic testing of the 11p15.5-associated imprinting disorders Silver-Russell and Beckwith-Wiedemann syndrome (SRS, BWS) is challenging due to the broad spectrum of molecular defects and their mosaic occurrence. Additionally, the decision on the molecular testing algorithm is hindered by their clinical heterogeneity. However, the precise identification of the type of defect is often a prerequisite for the clinical management and genetic counselling. Four major molecular alterations (epimutations, uniparental disomies, copy number variants, single nucleotide variants) have been identified, but their frequencies vary between SRS and BWS. Due to their molecular aetiology, epimutations in both disorders as well as upd(11)pat in BWS are particular prone to mosaicism which might additionally complicate the interpretation of testing results. We report on our experience of molecular analysis in a total cohort of 1448 patients referred for diagnostic testing of BWS and SRS, comprising a dataset from 737 new patients and from 711 cases from a recent study. Though the majority of positively tested patients showed the expected molecular results, we identified a considerable number of clinically unexpected molecular alterations as well as not yet reported changes and discrepant mosaic distributions. Additionally, the rate of multilocus imprinting disturbances among the patients with epimutations and uniparental diploidies could be further specified. Altogether, these cases show that comprehensive testing strategies have to be applied in diagnostic testing of SRS and BWS. The precise molecular diagnosis is required as the basis for a targeted management (e.g. ECG (electrocardiogram) and tumour surveillance in BWS, growth treatment in SRS). The molecular diagnosis furthermore provides the basis for genetic counselling. However, it has to be considered that recurrence risk calculation is determined by the phenotypic consequences of each molecular alteration and mechanism by which the alteration arose.

Key messages

The detection rates for the typical molecular defects of Beckwith-Wiedemann syndrome or Silver-Russell syndrome (BWS, SRS) are lower in routine cohorts than in clinically well-characterised ones.

A broad spectrum of (unexpected) molecular alterations in both disorders can be identified.

Multilocus imprinting disturbances (MLID) are less frequent in SRS than expected.

The frequency of MLID and uniparental diploidy in BWS is confirmed.

Mosaicism is a diagnostic challenge in BWS and SRS.

The precise determination of the molecular defects affecting is the basis for a targeted clinical management and genetic counselling.