New developments in Silver-Russell syndrome and implications for clinical practice

Approach to the Patient With Suspected Silver-Russell Syndrome

Silver-Russell syndrome (SRS) is a clinical diagnosis requiring the fulfillment of ≥ 4/6 Netchine-Harbison Clinical Scoring System (NH-CSS) criteria. A score of ≥ 4/6 NH-CSS (or ≥ 3/6 with strong clinical suspicion) warrants (epi)genetic confirmation, identifiable in ∼60% patients. The approach to the investigation and diagnosis of SRS is detailed in the only international consensus guidance, published in 2016. In the intervening years, the clinical, biochemical, and (epi)genetic characteristics of SRS have rapidly expanded, largely attributable to advancing molecular genetic techniques and a greater awareness of related disorders. The most common etiologies of SRS remain loss of methylation of chromosome 11p15 (11p15LOM) and maternal uniparental disomy of chromosome 7 (upd(7)mat). Rarer causes of SRS include monogenic pathogenic variants in imprinted (CDKN1C and IGF2) and non-imprinted (PLAG1 and HMGA2) genes. Although the age-specific NH-CSS can identify more common molecular causes of SRS, its use in identifying monogenic causes is unclear. Preliminary data suggest that NH-CSS is poor at identifying many of these cases. Additionally, there has been increased recognition of conditions with phenotypes overlapping with SRS that may fulfill NH-CSS criteria but have distinct genetic etiologies and disease trajectories. This group of conditions is frequently overlooked and under-investigated, leading to no or delayed diagnosis. Like SRS, these conditions are multisystemic disorders requiring multidisciplinary care and tailored management strategies. Early identification is crucial to improve outcomes and reduce the major burden of the diagnostic odyssey for patients and families. This article aims to enable clinicians to identify key features of rarer causes of SRS and conditions with overlapping phenotypes, show a logical approach to the molecular investigation, and highlight the differences in clinical management strategies.

EpiTyping: analysis of epigenetic aberrations in parental imprinting and X-chromosome inactivation using RNA-seq

Human pluripotent stem cells (hPSCs) hold a central role in studying human development, in disease modeling and in regenerative medicine. These cells not only acquire genetic modifications when kept in culture, but they may also harbor epigenetic aberrations, mainly involving parental imprinting and X-chromosome inactivation. Here we present a detailed bioinformatic protocol for detecting such aberrations using RNA sequencing data. We provide a pipeline designed to process and analyze RNA sequencing data for the identification of abnormal biallelic expression of imprinted genes, and thus detect loss of imprinting. Furthermore, we show how to differentiate among X-chromosome inactivation, full activation and aberrant erosion of X chromosome in female hPSCs. In addition to providing bioinformatic tools, we discuss the impact of such epigenetic variations in hPSCs on their utility for various purposes. This pipeline can be used by any user with basic understanding of the Linux command line. It is available on GitHub as a software container ( https://github.com/Gal-Keshet/EpiTyping ) and produces reliable results in 1-4 d.

Cryopreservation of Ovarian and Testicular Tissue and the Influence on Epigenetic Pattern

Ovarian tissue cryopreservation (OTC) or testicular tissue cryopreservation (TTC) are effective and often the only options for fertility preservation in female or male patients due to oncological, medical, or social aspects. While TTC and resumption of spermatogenesis, either in vivo or in vitro, has still be considered an experimental approach in humans, OTC and autotransplantation has been applied increasingly to preserve fertility, with more than 200 live births worldwide. However, the cryopreservation of reproductive cells followed by the resumption of gametogenesis, either in vivo or in vitro, may interfere with sensitive and highly regulated cellular processes. In particular, the epigenetic profile, which includes not just reversible modifications of the DNA itself but also post-translational histone modifications, small non-coding RNAs, gene expression and availability, and storage of related proteins or transcripts, have to be considered in this context. Due to complex reprogramming and maintenance mechanisms of the epigenome in germ cells, growing embryos, and offspring, OTC and TTC are carried out at very critical moments early in the life cycle. Given this background, the safety of OTC and TTC, taking into account the epigenetic profile, has to be clarified. Cryopreservation of mature germ cells (including metaphase II oocytes and mature spermatozoa collected via ejaculation or more invasively after testicular biopsy) or embryos has been used successfully for many years in medically assisted reproduction (MAR). However, tissue freezing followed by in vitro or in vivo gametogenesis has become more attractive in the past, while few human studies have analysed the epigenetic effects, with most data deriving from animal studies. In this review, we highlight the potential influence of the cryopreservation of immature germ cells and subsequent in vivo or in vitro growth and differentiation on the epigenetic profile (including DNA methylation, post-translational histone modifications, and the abundance and availability of relevant transcripts and proteins) in humans and animals.

Congenital absence of the bilateral long heads of the biceps brachii tendons in a patient with Silver-Russell syndrome

Agenesis of the long head of biceps tendon (LHBT) is a congenital anomaly not commonly reported in the literature, and bilateral absence of the LHBT is even more rare. Most cases of LHBT agenesis are found incidentally at arthroscopy or are diagnosed by magnetic resonance imaging after a history of insidious shoulder pain or anterior shoulder instability. We present the magnetic resonance imaging findings of bilateral congenital absence of the LHBT in a 37-year-old male with Silver-Russell syndrome who presented with progressive, bilateral anterior shoulder pain after failing conservative treatment strategies. This case report describes bilateral agenesis of the LHBT in association with a congenital growth disorder that has not been described previously in the literature. We provide a description of key MR imaging findings to assist in making the diagnosis, along with a discussion of potential differential diagnoses, and a review of the current literature on this topic.

Prenatal Silver-Russell Syndrome in a Chinese Family Identified by Non-Invasive Prenatal Testing

Russell-Silver syndrome (SRS) is a rare condition characterized by poor growth before and after birth along with multiple physical and psychosocial characteristics such as short stature, characteristic facial features, body asymmetry, feeding difficulties, and learning disabilities. In this study, we report a family with 2 recurrent SRS pregnancies due to a derivative chromosome 15 that is the result of a maternally derived t(11;15) translocation, detected by non-invasive prenatal testing (NIPT). The 2 SRS fetuses were diagnosed by chromosomal microarray analysis, but a balanced, reciprocal translocation of the mother was disclosed by the combination of routine karyotyping and FISH. This study demonstrates that NIPT has the ability to identify submicroscopic copy number variations (CNVs) in fetuses, which in some cases may result from a parent being a balanced rearrangement carrier. Because of the differences in resolution and the various benefits and limitations of each genetic technique, great care must be taken when deciding on which test(s) to employ in family studies.

The Methylation Status in the Chromosome 11p15.5 Region and Metabolic Disorders in Children with Syndromic and Nonsyndromic Intrauterine Growth Restriction

Loss of methylation (LoM) of the imprinting control region 1 (ICR1) in the chromosome 11p15.5 domain is detected in patients with Silver-Russell syndrome (SRS), characterized by asymmetric pre- and postnatal growth restriction, and typical craniofacial features. The patients with intrauterine growth restriction (IUGR) possess a high risk for adult metabolic problems. This study is aimed to investigate the methylation levels of the chromosome 11p15.5 region and metabolic problems in children with syndromic and nonsyndromic IUGR. Methylation analysis was performed for chromosome 11p15.5 in 49 patients (33 with suspected SRS and 16 nonsyndromic IUGR) with Netchine-Harbison clinical scoring (NHCS); uniparental disomy for chromosomes 6, 7, 14, and 20 was evaluated for those who were negative. LoM of ICR1 was detected in 14 of 33 suspected SRS patients with 3 or more criteria of NHCS, 5 had borderline LoM. Maternal uniparental disomy of the chromosomes 7 and 14 was found in 2 patients. The overall detection rate of SRS was 45.5%. While clinical findings were similar in patients with LoM and borderline LoM of ICR1, typical craniofacial findings were significantly less in the patients with normal methylation. Methylation patterns were not found to be impaired in the nonsyndromic IUGR group. Metabolic complications were evaluated in a total of 63 patients including 33 SRS-suspicious, 16 nonsyndromic IUGR, and 14 patients with 3M or SHORT syndrome. Increased rates of hypercalciuria, insulin resistance, and dyslipidemia were detected in patients with both syndromic and nonsyndromic IUGR. We would like to emphasize that detecting typical facial findings is effective in the diagnosis of SRS and paying attention to metabolic problems in the follow-up of patients with IUGR is recommended.

Silver-Russell syndrome: clinical, neurodevelopmental and communication characteristics: clinical case studies

Silver Russell Syndrome (SRS) is a genetically heterogeneous condition with a clinical phenotype that includes intrauterine and postnatal growth restriction, craniofacial alterations, body asymmetries, low body mass index, and feeding difficulties. Alterations in motor development, global coordination, and speech are expected. The current study aims to present the syndrome, neurodevelopment, and communication characteristics of three male children diagnosed with the syndrome, aged 16, 18, and 44 months, respectively. Ethical principles were followed. An analysis of the medical records, aiming to collect information of the anamnesis, conducted with the guardians, and of the assessment carried out with the children was performed. The assessment was performed by applying the following instruments: Communicative Behavior Observation (CBO), Development Screening Test Denver-II (TSDD-II), and the Early Language Milestone Scale (ELMS). The survey of characteristics confirmed the SRS hypothesis; it was verified a delay in communicative behavior for all participants in CBO; in TSDD-II there was a delay in gross motor, fine motor-adaptive, language, and social personal skills. Scores below expectations were found for receptive auditory and expressive auditory functions, with receptive abilities more developed than expressive abilities, in ELM. The SRS deserves to be recognized by the scientific community, since the phenotypic characteristics and the data from the previous life allow the hypothesis of the syndrome to be raised, aiming at an early correct diagnosis and therapeutic planning that minimizes the harmful effects of this condition.

Acquired uniparental disomy of chromosome 7 in a patient with MIRAGE syndrome that veiled a pathogenic SAMD9 variant

Gain-of-function variants in SAMD9, which resides on chromosome 7, cause MIRAGE syndrome that is associated with congenital adrenal insufficiency and gonadal dysgenesis. We previously reported a Japanese patient with MIRAGE syndrome carrying a de novo heterozygous SAMD9 variant (p.Ala1479Ser). In this study, we confirmed the pathogenicity of Ala1479Ser-SAMD9 in vitro. Genetic study results revealed an atypically low variant allele frequency (26%) and we suspected of genomic rearrangement(s) involving chromosome 7. Single nucleotide polymorphism (SNP) array and short tandem repeat analysis showed presence of mosaic maternal isodisomic uniparental disomy 7 (UPD7). Deep sequencing using DNA samples obtained at 0, 6, 10, and 25 mo of age revealed that the percentage of cells with UPD7 increased constantly from 6% to 82% over 25 mo, and this increase coincided with a decrease in the percentage of cells with p.Ala1479Ser from 94% to nearly undetectable levels. We further screened for low-allele-frequency and rare SAMD9 variants in eight patients with Silver-Russel syndrome and maternal UPD7; however, none of the patients harbored such a variant. In conclusion, our case demonstrates that genetic findings can vary considerably in patients with MIRAGE syndrome and that a comprehensive diagnostic approach, including SNP array and deep sequencing, is important in such cases.

Developmental origins of metabolic diseases

Almost 2 billion adults in the world are overweight, and more than half of them are classified as obese, while nearly one-third of children globally experience poor growth and development. Given the vast amount of knowledge that has been gleaned from decades of research on growth and development, a number of questions remain as to why the world is now in the midst of a global epidemic of obesity accompanied by the "double burden of malnutrition," where overweight coexists with underweight and micronutrient deficiencies. This challenge to the human condition can be attributed to nutritional and environmental exposures during pregnancy that may program a fetus to have a higher risk of chronic diseases in adulthood. To explore this concept, frequently called the developmental origins of health and disease (DOHaD), this review considers a host of factors and physiological mechanisms that drive a fetus or child toward a higher risk of obesity, fatty liver disease, hypertension, and/or type 2 diabetes (T2D). To that end, this review explores the epidemiology of DOHaD with discussions focused on adaptations to human energetics, placental development, dysmetabolism, and key environmental exposures that act to promote chronic diseases in adulthood. These areas are complementary and additive in understanding how providing the best conditions for optimal growth can create the best possible conditions for lifelong health. Moreover, understanding both physiological as well as epigenetic and molecular mechanisms for DOHaD is vital to most fully address the global issues of obesity and other chronic diseases.

Chronic Hypercapnic Respiratory Failure in an Adult Patient with Silver-Russell Syndrome

A 31-year-old woman who was clinically diagnosed with Silver-Russell syndrome (SRS) in childhood was admitted with complaints of dyspnea. She had hypercapnic respiratory failure accompanied by nocturnal hypoventilation. Computed tomography revealed systemic muscle atrophy and superior mesenteric artery syndrome; however, the bilateral lung fields were normal. She was treated with nocturnal noninvasive positive pressure ventilation and showed improvement of respiratory failure. In this case, loss of methylation on chromosome 11p15 and maternal uniparental disomy of chromosome 7, which are the common causes of SRS, were not detected. This is a rare case of adult SRS manifesting as chronic hypercapnic respiratory failure.

Isolated Hypomethylation of IGF2 Associated with Severe Hypoglycemia Responsive to Growth Hormone Treatment

Hypomethylation of H19 and IGF2 can cause Silver-Russell syndrome (SRS), a clinically and genetically heterogeneous condition characterized by intrauterine growth restriction, poor postnatal growth, relative macrocephaly, craniofacial abnormalities, body asymmetry, hypoglycemia and feeding difficulties. Isolated hypomethylation of IGF2 has been reported in single cases of SRS as well. Here, we report on a 19-month-old patient who presented with two episodes of hypoglycemic seizures. No intrauterine growth restriction was observed, the patient did not present with SRS-typical facial features, and postnatal growth in the first months of life was along the lower normal percentiles. Exome sequencing did not reveal any likely pathogenic variants explaining the phenotype; however, hypomethylation studies revealed isolated hypomethylation of IGF2, while the methylation of H19 appeared normal. Hypoglycemia responded well to growth hormone therapy, and the boy showed good catch-up growth. Our case demonstrates that SRS and isolated IGF2 hypomethylation should be considered early in the diagnosis of recurrent hypoglycemia in childhood, especially in combination with small gestational age and poor growth.

A pilot study of expanded newborn screening for 573 genes related to severe inherited disorders in China: results from 1,127 newborns

Background

Newborn screening (NBS) in China is mainly aimed at detecting biochemical levels of metabolites in the blood, which may generate false-positive/negative results. Current biochemical NBS includes tandem mass spectrometry (MS/MS) screening for metabolites as well as phenylalanine (Phe), thyroid-stimulating hormone (TSH), 17-α-hydroxyprogesterone (17-OHP), and glucose-6-phosphate dehydrogenase (G6PD) test. This study intended to explore whether next-generation sequencing (NGS) for dried blood spots combining with biochemical screening could improve the current screening efficiency and to investigate the carrier frequencies of mutations in causative genes related to amino acid metabolism, organic acid metabolism, and fatty acid oxidation in this cohort.

Methods

We designed a panel of 573 genes related to severe inherited disorders and performed NGS in 1,127 individuals who had undergone biochemical NBS. The NGS screening results of neonates were used to compare with the biochemical results.

Results

NGS screening results revealed that all the four newborns with abnormal G6PD values carried hemizygous G6PD mutations, which were consistent with the decreased G6PD enzymatic activity. The NGS results revealed an individual with compound heterozygous mutations of SLC22A5, who was biochemically negative in 2016. The MS/MS screening results in 2019 showed free carnitine deficiency, which was consistent with the genetic findings. The top five genes with the highest carrier frequencies of mutations in these newborns were PAH (1:56, 1.79%), ETFDH (1:81, 1.23%), MMACHC (1:87, 1.15%), SLC25A13 (1:102, 0.98%), and GCDH (1:125, 0.80%).

Conclusions

Our study highlighted that combining NGS screening with biochemical screening could improve the current NBS efficiency. This is the first study to investigate carrier frequencies of mutations in 77 genes causing inherited metabolic diseases (IMDs) in China.

Successful generation of epigenetic disease model mice by targeted demethylation of the epigenome

BACKGROUND

Epigenetic modifications, including DNA methylation, play an important role in gene silencing and genome stability. Consequently, epigenetic dysregulation can cause several diseases, such as cancer, obesity, diabetes, autism, and imprinting disorders.

RESULTS

We validate three methods for the generation of epigenome-edited mice using the dCas9-SunTag and single-chain variable fragment-TET1 catalytic domain. We generate model mice for Silver-Russell syndrome (SRS), an imprinting disorder, by target-specific DNA demethylation in the H19 differentially methylated region. Like SRS patients, these mice show H19 upregulation and Igf2 downregulation, leading to severe intrauterine and postnatal growth retardation.

CONCLUSION

This is the first report of an imprinting disease model animal generated by targeted demethylation of specific loci of the epigenome in fertilized eggs. Epigenome-edited animals are also useful for exploring the causative epimutations in epigenetic diseases.

A spontaneous pregnancy and successful delivery in a Chinese female with Silver-Russell syndrome accompanied by gestational diabetes mellitus

Silver-Russell syndrome (SRS) is a heterogeneous disorder characterized by severe intrauterine and postnatal growth retardation and typical dysmorphic features including body asymmetry, relative macrocephaly, protruding forehead, and feeding difficulties. Previous descriptions of SRS focus on the management of specific issues in children. Herein, we present clinical and metabolic characteristics of an adult woman with SRS accompanied by gestational diabetes mellitus (GDM). Given the rare circumstances presented in our case, the emerging questions concerning the management of metabolic issues and fertility potential in adult SRS patient deserve more attention. Further, long-term follow up is essential to gain future insights into the natural history and optimal management in adulthood.

Nonclassical GH Insensitivity: Characterization of Mild Abnormalities of GH Action

GH insensitivity (GHI) presents in childhood with growth failure and in its severe form is associated with extreme short stature and dysmorphic and metabolic abnormalities. In recent years, the clinical, biochemical, and genetic characteristics of GHI and other overlapping short stature syndromes have rapidly expanded. This can be attributed to advancing genetic techniques and a greater awareness of this group of disorders. We review this important spectrum of defects, which present with phenotypes at the milder end of the GHI continuum. We discuss their clinical, biochemical, and genetic characteristics. The objective of this review is to clarify the definition, identification, and investigation of this clinically relevant group of growth defects. We also review the therapeutic challenges of mild GHI.

Alteration in methylation level at differential methylated regions of MEST and DLK1 in fetus of preeclampsia

OBJECTIVES

Offspring born to preeclamptic women are at high risk for metabolic diseases in later life, but the mechanisms are not known. The purposes of the current investigation were to clarify the changes in DNA methylation at MEST and DLK1 DMRs in fetus of preeclampsia and to explore the possible mechanisms behind the high risk of adult diseases in the offspring of preeclampsia.

METHODS

Fetal lymphocytes were isolated from umbilical cord blood of 78 women with preeclampsia and 95 women with normal pregnancy. Genomic DNA was extracted and then DNA methylation levels of MEST and DLK1 DMRs were determined by MassARRAY quantitative methylation analysis.

RESULTS

The methylation levels were detected in 20 CpG sites of MEST DMR and 16 sites of DLK1 DMR. Methylation changes were significantly different at CPG1, 3, 4, 7.8, 15, 18.19, and 20 of MEST between preeclampsia and normal pregnancy (P = 0.014, 0.001, <0.001, <0.001, = 0.001,  = 0.005, and = 0.003, respectively). Significant differences were also observed at CPG 3 and 9 of DLK1 (P = 0.002 and 0.027, respectively). However, overall methylation at these DMRs were not affected.

CONCLUSION

We conclude methylation changes at some CpG sites of MEST and DLK DMRs in preeclamptic group. This may be among the mechanisms behind the high risk of adult diseases in the later life of offspring born to preeclamptic pregnancies.

ABBREVIATIONS

DMR: Differentially Methylated Region; MEST: Mesoderm Specific Transcript.

Mosaic UPD(7q)mat in a patient with silver Russell syndrome

BACKGROUND

Silver-Russell syndrome (SRS) is one of the imprinting disorders characterized by prenatal and postnatal growth restriction, relative macrocephaly, body asymmetry and characteristic facial features. ~ 10% of SRS cases are known to be associated with maternal uniparental disomy of chromosome 7 (UPD(7)mat). Mosaic maternal segmental UPD of 7q (UPD(7q)mat) is very rare, had only been described in one case before.

CASE PRESENTATION

We reported a second case of mosaic segmental UPD involving 7q. The patient presented with dysmorphic features including thin and short stature, triangular face, moderate protruding forehead, relative macrocephaly, fifth toe clinodactyly and irregular teeth, meeting the clinical diagnosed criteria of SRS. This case indicated that ~ 80% of mosaic UPD(7q)mat lead to the manifestation of main phenotypes of Silver-Russell syndrome.

CONCLUSIONS

Our case support the notion that there are genes control postnatal growth on long arm of chromosome 7 and indicate that ~ 80% of UPD(7q)mat mosaicism level was contributed to the SRS phenotype.

[Rare diseases with clinical relevance-the Silver-Russell syndrome]

The Silver-Russell syndrome (SRS) is a rare imprinting disease associated with pre- and postnatal growth retardation, craniofacial features, and asymmetry. Genitourinary abnormalities are seen in up to 20% of affected individuals. Apart from structural renal anomalies, cryptorchidism and hypospadias occur frequently in boys, while girls often have anomalies similar to those in Mayer-Rokitansky-Küster-Hauser syndrome with congenital hypoplasia or aplasia of the uterus and upper part of the vagina. Frequently hypospadias repair and orchiopexy are difficult because of lack of buccal mucosa due to facial dysmorphism and intraabdominal position of the testicles, respectively. Anesthetic problems with SRS children can be profound and mostly concern a difficult airway due to facial dysmorphism. Especially the young, very thin SRS patients are prone to hypoglycemia and hypothermia and require close perioperative monitoring. Children with SRS and their families face challenges from birth to adulthood. In case of urogenital abnormalities, they should receive multidisciplinary care by pediatric urologists/surgeons and pediatric anesthesiologists in a center of expertise in rare diseases.