scholarly journals Blended Phenotype of Silver-Russell Syndrome and SPG50 Caused by Maternal Isodisomy of Chromosome 7

2020 ◽  
Vol 7 (1) ◽  
pp. e544
Author(s):  
Marvin Ziegler ◽  
Bianca E. Russell ◽  
Kathrin Eberhardt ◽  
Gregory Geisel ◽  
Angelica D'Amore ◽  
...  
Keyword(s):  
Short Stature ◽  
Neurodevelopmental Disorder ◽  
Brain Mri ◽  
Adaptor Protein ◽  
Chromosome 7 ◽  
Imprinting Disorders ◽  
Feeding Difficulties ◽  
Functional Studies ◽  
Uniparental Isodisomy ◽  
Silver Russell Syndrome

ObjectiveUniparental isodisomy can lead to blended phenotypes of imprinting disorders and autosomal recessive diseases. To determine whether a complex neurodevelopmental disorder was caused by uniparental isodisomy, a detailed clinical and molecular characterization was performed.MethodsA combination of clinical, molecular, and imaging data and functional studies in patient-derived fibroblasts.ResultsWe report a 4-year-old female with a blended, complex phenotype of Silver-Russell syndrome (SRS) and hereditary spastic paraplegia type 50 (SPG50) caused by total maternal isodisomy of chromosome 7 (UPiD(7)mat) and a loss-of-function variant in AP4M1 (NM_00472.3: c.59-1G>C, IVS1-1G>C). Functional studies in patient-derived fibroblasts confirmed the loss of adaptor protein complex 4 function. Distinctive facial features, intrauterine growth restriction, short stature, feeding difficulties, and severe gastroesophageal reflux were consistent with SRS. Features associated with SPG50 included early-onset epilepsy, episodes of stereotypical laughter, and thinning of the corpus callosum and ventriculomegaly on brain MRI. Symptoms shared by both syndromes such as developmental delay, short stature, and axial and appendicular hypotonia were also present. Notably, other common manifestations of SPG50 such as microcephaly or spasticity had not developed yet.ConclusionsThis case highlights that atypical clinical features in patients with well-described imprinting disorders should lead to investigations for recessive conditions caused by variants in genes that localize to the region of homozygosity.

scholarly journals Highly clustered de novo frameshift variants in the neuronal splicing factor NOVA2 result in a specific abnormal C terminal part and cause a severe form of intellectual disability with autistic features

2019 ◽  
Author(s):  
Francesca Mattioli ◽  
Gaelle Hayot ◽  
Nathalie Drouot ◽  
Bertrand Isidor ◽  
Jérémie Courraud ◽  
...  
Keyword(s):  
Intellectual Disability ◽  
Rna Binding ◽  
De Novo ◽  
Neurodevelopmental Disorder ◽  
Brain Mri ◽  
Severe Form ◽  
Neural Cells ◽  
Loss Of Function ◽  
Ataxic Gait ◽  
Feeding Difficulties

ABSTRACTThe Neuro-Oncological Ventral Antigen 2 NOVA2 protein is a major factor regulating neuron specific alternative splicing, previously associated with an acquired neurologic condition, the paraneoplastic opsoclonus-myoclonus ataxia (POMA). We report here six individuals with de novo frameshift variants in the NOVA2 gene affected with a severe neurodevelopmental disorder characterized by intellectual disability (ID), motor and speech delay, autistic features, hypotonia, feeding difficulties, spasticity or ataxic gait and abnormal brain MRI. The six variants lead to the same reading frame, adding a common 133 aa long proline rich C-terminus part instead of the last KH RNA binding domain. We detected forty-one genes differentially spliced after NOVA2 inactivation in human neural cells. The mutant NOVA2 protein shows decreased ability to bind a target RNA, to regulate specific splicing events and to rescue the phenotype of altered retinotectal axonal pathfinding induced by loss of NOVA2 ortholog in zebrafish. Our results suggest a partial loss-of-function mechanism rather than a full heterozygous loss of function, although a specific contribution of the novel C terminal extension cannot be excluded on the basis of the genetic findings.

scholarly journals Biallelic variants in the RNA exosome gene EXOSC5 are associated with developmental delays, short stature, cerebellar hypoplasia and motor weakness

2020 ◽  
Vol 29 (13) ◽  
pp. 2218-2239 ◽  
Author(s):  
Anne Slavotinek ◽  
Doriana Misceo ◽  
Stephanie Htun ◽  
Linda Mathisen ◽  
Eirik Frengen ◽  
...  
Keyword(s):  
Short Stature ◽  
Mammalian Cells ◽  
Developmental Delays ◽  
Brain Mri ◽  
Missense Variant ◽  
Cerebellar Hypoplasia ◽  
Loss Of Function ◽  
Feeding Difficulties ◽  
In Trans ◽  
Rna Exosome

Abstract The RNA exosome is an essential ribonuclease complex required for processing and/or degradation of both coding and non-coding RNAs. We identified five patients with biallelic variants in EXOSC5, which encodes a structural subunit of the RNA exosome. The clinical features of these patients include failure to thrive, short stature, feeding difficulties, developmental delays that affect motor skills, hypotonia and esotropia. Brain MRI revealed cerebellar hypoplasia and ventriculomegaly. While we ascertained five patients, three patients with distinct variants of EXOSC5 were studied in detail. The first patient had a deletion involving exons 5–6 of EXOSC5 and a missense variant, p.Thr114Ile, that were inherited in trans, the second patient was homozygous for p.Leu206His and the third patient had paternal isodisomy for chromosome 19 and was homozygous for p.Met148Thr. The additional two patients ascertained are siblings who had an early frameshift mutation in EXOSC5 and the p.Thr114Ile missense variant that were inherited in trans. We employed three complementary approaches to explore the requirement for EXOSC5 in brain development and assess consequences of pathogenic EXOSC5 variants. Loss of function for exosc5 in zebrafish results in shortened and curved tails/bodies, reduced eye/head size and edema. We modeled pathogenic EXOSC5 variants in both budding yeast and mammalian cells. Some of these variants cause defects in RNA exosome function as well as altered interactions with other RNA exosome subunits. These findings expand the number of genes encoding RNA exosome subunits linked to human disease while also suggesting that disease mechanism varies depending on the specific pathogenic variant.

scholarly journals A New Case of de novo Variant c.892C>T (p.Arg298Trp) in NACC1: A First Case Report From China

2021 ◽  
Vol 9 ◽  
Author(s):  
Baiyu Lyu ◽  
Yan Dong ◽  
Juan Kang
Keyword(s):  
Intellectual Disability ◽  
Congenital Cataract ◽  
De Novo ◽  
Neurodevelopmental Disorder ◽  
Brain Mri ◽  
Case Presentation ◽  
Feeding Difficulties ◽  
Severe Intellectual Disability ◽  
First Case ◽  
Infantile Epilepsy

Background: The nucleus accumbens associated 1 (NACC1) gene is a transcription factor member of the BTB/POZ family. A de novo heterozygous c.892C>T (p.Arg298Trp) variant in the NACC1 may define a syndrome characterized by intellectual disability, infantile epilepsy, congenital cataract, and feeding difficulties.Case Presentation: We report a new case with a neurodevelopmental disorder characterized by severe intellectual disability, infantile epilepsy, congenital cataract, and feeding difficulties. Brain MRI reveals brain dysplasia. We observe a de novo heterozygous c.892C>T (p.Arg298Trp) variant in the NACC1 gene in this case. Now, the child regularly goes to the hospital for rehabilitation training (once a month). Sodium Valproate (10 mg/kg/day) and Clobazam (10 mg/kg/day) are used in the treatment of epilepsy. A total of three articles were screened, and two papers were excluded. The search revealed one article related to a syndrome caused by a de novo heterozygous c.892C>T (p.Arg298Trp) variant in the NACC1; they screened the main clinical features of eight cases of a syndrome, which were summarized and analyzed.Conclusions: The NACC1 gene is a member of the BTB/POZ family of transcription factors. A de novo heterozygous c.892C>T (p.Arg298Trp) variant in the NACC1 may define a syndrome characterized by intellectual disability, infantile epilepsy, congenital cataract, and feeding difficulties. At present, there is no effective cure. In the future, we need more cases to determine the phenotype–genotype correlation of NACC1 variants. Many questions remain to be answered, and many challenges remain to be faced. Future transcriptional studies may further clarify this rare, recurrent variant, and could potentially lead to targeted therapies.

Hepatomegaly and hyperammonemia in a girl with Silver-Russell syndrome caused by maternal uniparental isodisomy of chromosome 7

2014 ◽  
Vol 164 (8) ◽  
pp. 2114-2117
Author(s):  
Cheng-Fang Li ◽  
Hsiang-Yu Lin ◽  
Hao-Chuan Liu ◽  
Sheng-Hung Lee ◽  
Ming-Yu Lo ◽  
...  
Keyword(s):  
Chromosome 7 ◽  
Uniparental Isodisomy ◽  
Silver Russell Syndrome

scholarly journals Biallelic variants in the RNA exosome gene EXOSC5 are associated with developmental delays, short stature, cerebellar hypoplasia and motor weakness

2020 ◽  
Author(s):  
Anne Slavotinek ◽  
Doriana Misceo ◽  
Stephanie Htun ◽  
Linda Mathisen ◽  
Eirik Frengen ◽  
...  
Keyword(s):  
Short Stature ◽  
Mammalian Cells ◽  
Developmental Delays ◽  
Brain Mri ◽  
Failure To Thrive ◽  
Missense Variant ◽  
Cerebellar Hypoplasia ◽  
Loss Of Function ◽  
Feeding Difficulties ◽  
Rna Exosome

AbstractThe RNA exosome is an essential ribonuclease complex involved in the processing and degradation of both coding and noncoding RNAs. We present three patients with biallelic variants in EXOSC5, which encodes a structural subunit of the RNA exosome. The common clinical features of these patients comprise failure to thrive, short stature, feeding difficulties, developmental delays that affect motor skills, hypotonia and esotropia. Brain MRI revealed cerebellar hypoplasia and ventriculomegaly. The first patient had a deletion involving exons 5-6 of EXOSC5 and a missense variant, p.Thr114Ile, that were inherited in trans, the second patient was homozygous for p.Leu206His, and the third patient had paternal isodisomy for chromosome 19 and was homozygous for p.Met148Thr. We employed three complementary approaches to explore the requirement for EXOSC5 in brain development and assess the functional consequences of pathogenic variants in EXOSC5. Loss of function for the zebrafish ortholog results in shortened and curved tails and bodies, reduced eye and head size and edema. We modeled pathogenic EXOSC5 variants in both budding yeast and mammalian cells. Some of these variants show defects in RNA exosome function as well as altered interactions with other RNA exosome subunits. Overall, these findings expand the number of genes encoding RNA exosome components that have been implicated in human disease, while also suggesting that disease mechanism varies depending on the specific pathogenic variant.

scholarly journals Maternal Uniparental Disomy of Chromosome 20 (UPD(20)mat) as Differential Diagnosis of Silver Russell Syndrome: Identification of Three New Cases

Genes ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 588
Author(s):  
Pierpaola Tannorella ◽  
Daniele Minervino ◽  
Sara Guzzetti ◽  
Alessandro Vimercati ◽  
Luciano Calzari ◽  
...  
Keyword(s):  
Growth Retardation ◽  
Molecular Mechanisms ◽  
Uniparental Disomy ◽  
Postnatal Growth ◽  
Molecular Diagnostic ◽  
Growth Delay ◽  
Molecular Defect ◽  
Maternal Uniparental Disomy ◽  
Feeding Difficulties ◽  
Silver Russell Syndrome

Silver Russell Syndrome (SRS, MIM #180860) is a rare growth retardation disorder in which clinical diagnosis is based on six features: pre- and postnatal growth failure, relative macrocephaly, prominent forehead, body asymmetry, and feeding difficulties (Netchine–Harbison clinical scoring system (NH-CSS)). The molecular mechanisms consist in (epi)genetic deregulations at multiple loci: the loss of methylation (LOM) at the paternal H19/IGF2:IG-DMR (chr11p15.5) (50%) and the maternal uniparental disomy of chromosome 7 (UPD(7)mat) (10%) are the most frequent causes. Thus far, about 40% of SRS remains undiagnosed, pointing to the need to define the rare mechanisms in such a consistent fraction of unsolved patients. Within a cohort of 176 SRS with an NH-CSS ≥ 3, a molecular diagnosis was disclosed in about 45%. Among the remaining patients, we identified in 3 probands (1.7%) with UPD(20)mat (Mulchandani–Bhoj–Conlin syndrome, OMIM #617352), a molecular mechanism deregulating the GNAS locus and described in 21 cases, characterized by severe feeding difficulties associated with failure to thrive, preterm birth, and intrauterine/postnatal growth retardation. Our patients share prominent forehead, feeding difficulties, postnatal growth delay, and advanced maternal age. Their clinical assessment and molecular diagnostic flowchart contribute to better define the characteristics of this rare imprinting disorder and to rank UPD(20)mat as the fourth most common pathogenic molecular defect causative of SRS.

scholarly journals In Pursuit of New Imprinting Syndromes by Epimutation Screening in Idiopathic Neurodevelopmental Disorder Patients

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Sonia Mayo ◽  
Sandra Monfort ◽  
Mónica Roselló ◽  
Silvestre Oltra ◽  
Carmen Orellana ◽  
...  
Keyword(s):  
Clinical Features ◽  
Neurodevelopmental Disorders ◽  
Neurodevelopmental Disorder ◽  
Epigenetic Mechanisms ◽  
Proof Of Concept ◽  
Partial Loss ◽  
Imprinting Disorders ◽  
Initial Hypothesis ◽  
Definition Of ◽  
Methylation Patterns

Alterations of epigenetic mechanisms, and more specifically imprinting modifications, could be responsible of neurodevelopmental disorders such as intellectual disability (ID) or autism together with other associated clinical features in many cases. Currently only eight imprinting syndromes are defined in spite of the fact that more than 200 genes are known or predicted to be imprinted. Recent publications point out that some epimutations which cause imprinting disorders may affect simultaneously different imprintedloci, suggesting that DNA-methylation may have been altered more globally. Therefore, we hypothesised that the detection of altered methylation patterns in known imprintinglociwill indirectly allow identifying new syndromes due to epimutations among patients with unexplained ID. In a screening for imprinting alterations in 412 patients with syndromic ID/autism we found five patients with altered methylation in the four genes studied:MEG3, H19, KCNQ1OT1, andSNRPN. Remarkably, the cases with partial loss of methylation inKCNQ1OT1andSNRPNpresent clinical features different to those associated with the corresponding imprinting syndromes, suggesting a multilocus methylation defect in accordance with our initial hypothesis. Consequently, our results are a proof of concept that the identification of epimutations in knownlociin patients with clinical features different from those associated with known syndromes will eventually lead to the definition of new imprinting disorders.

Neurodevelopmental disorder with dysmorphic facies and distal limb anomalies syndrome due to disruption of BPTF in a 35-year-old man initially diagnosed with Silver-Russell syndrome

2019 ◽  
Vol 95 (4) ◽  
pp. 534-536 ◽  
Author(s):  
Alina T. Midro ◽  
Niels Tommerup ◽  
Jan Borys ◽  
Barbara Panasiuk ◽  
Bożena Kosztyła-Hojna ◽  
...  
Keyword(s):  
Neurodevelopmental Disorder ◽  
Distal Limb ◽  
Limb Anomalies ◽  
Silver Russell Syndrome

scholarly journals Early infantile epileptic-dyskinetic encephalopathy due to biallelic PIGP mutations

2020 ◽  
Vol 6 (1) ◽  
pp. e387 ◽  
Author(s):  
Annalisa Vetro ◽  
Tiziana Pisano ◽  
Silvia Chiaro ◽  
Elena Procopio ◽  
Azzurra Guerra ◽  
...  
Keyword(s):  
Neurodevelopmental Disorder ◽  
Brain Mri ◽  
Molecular Genetic ◽  
Genetic Diagnosis ◽  
Premature Death ◽  
Epileptic Encephalopathy ◽  
Whole Exome ◽  
Mri Scans ◽  
Severe Hypotonia ◽  
Profound Disability

ObjectiveTo describe clinical, biochemical, and molecular genetic findings in a large inbred family in which 4 children with a severe early-onset epileptic-dyskinetic encephalopathy, with suppression burst EEG, harbored homozygous mutations of phosphatidylinositol glycan anchor biosynthesis, class P (PIGP), a member of the large glycosylphosphatidylinositol (GPI) anchor biosynthesis gene family.MethodsWe studied clinical features, EEG, brain MRI scans, whole-exome sequencing (WES), and measured the expression of a subset of GPI-anchored proteins (GPI-APs) in circulating granulocytes using flow cytometry.ResultsThe 4 affected children exhibited a severe neurodevelopmental disorder featuring severe hypotonia with early dyskinesia progressing to quadriplegia, associated with infantile spasms, focal, tonic, and tonic-clonic seizures and a burst suppression EEG pattern. Two of the children died prematurely between age 2 and 12 years; the remaining 2 children are aged 2 years 7 months and 7 years 4 months. The homozygous c.384del variant of PIGP, present in the 4 patients, introduces a frame shift 6 codons before the expected stop signal and is predicted to result in the synthesis of a protein longer than the wild type, with impaired functionality. We demonstrated a reduced expression of the GPI-AP CD16 in the granulocytic membrane in affected individuals.ConclusionsPIGP mutations are consistently associated with an epileptic-dyskinetic encephalopathy with the features of early infantile epileptic encephalopathy with profound disability and premature death. CD16 is a valuable marker to support a genetic diagnosis of inherited GPI deficiencies.

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