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International Journal of Molecular... Oct 2023The impact of segmental duplications on human evolution and disease is only just starting to unfold, thanks to advancements in sequencing technologies that allow for...
The impact of segmental duplications on human evolution and disease is only just starting to unfold, thanks to advancements in sequencing technologies that allow for their discovery and precise genotyping. The 15q11-q13 locus is a hotspot of recurrent copy number variation associated with Prader-Willi/Angelman syndromes, developmental delay, autism, and epilepsy and is mediated by complex segmental duplications, many of which arose recently during evolution. To gain insight into the instability of this region, we characterized its architecture in human and nonhuman primates, reconstructing the evolutionary history of five different inversions that rearranged the region in different species primarily by accumulation of segmental duplications. Comparative analysis of human and nonhuman primate duplication structures suggests a human-specific gain of directly oriented duplications in the regions flanking the cores and segmental duplications, representing potential genomic drivers for the human-specific expansions. The increasing complexity of segmental duplication organization over the course of evolution underlies its association with human susceptibility to recurrent disease-associated rearrangements.
Topics: Animals; Humans; DNA Copy Number Variations; Primates; Prader-Willi Syndrome; Segmental Duplications, Genomic; Autistic Disorder; Chromosomes, Human, Pair 15; Gene Duplication
PubMed: 37958807
DOI: 10.3390/ijms242115818 -
Journal of Neurodevelopmental Disorders Nov 2023The objective of this study was to identify the age of diagnosis for children with one of three neurogenetic conditions resulting from changes in chromosome 15 (Angelman...
OBJECTIVE
The objective of this study was to identify the age of diagnosis for children with one of three neurogenetic conditions resulting from changes in chromosome 15 (Angelman syndrome [AS], Prader-Willi syndrome [PWS], and duplication 15q syndrome [Dup15q]).
METHODS
Data about the diagnostic process for each condition were contributed by the advocacy organizations. Median and interquartile ranges were calculated for each condition by molecular subtype and year. Comparison tests were run to explore group differences.
RESULTS
The median age of diagnosis was 1.8 years for both AS and Dup15q. PWS was diagnosed significantly younger at a median age of 1 month. Deletion subtypes for both PWS and AS were diagnosed earlier than nondeletion subtypes, and children with isodicentric duplications in Dup15q were diagnosed earlier than those with interstitial duplications.
CONCLUSION
Understanding variability in the age of diagnosis for chromosome 15 disorders is an important step in reducing the diagnostic odyssey and improving access to interventions for these populations. Results from this study provide a baseline by which to evaluate efforts to reduce the age of diagnosis for individuals with these conditions.
Topics: Humans; Child; Infant; Prader-Willi Syndrome; Chromosome Disorders; Chromosomes; Angelman Syndrome; Trisomy
PubMed: 37936142
DOI: 10.1186/s11689-023-09504-x -
Frontiers in Cell and Developmental... 2023Angelman syndrome (AS) is an imprinted neurodevelopmental disorder that lacks a cure, characterized by developmental delay, intellectual impairment, seizures, ataxia,... (Review)
Review
Angelman syndrome (AS) is an imprinted neurodevelopmental disorder that lacks a cure, characterized by developmental delay, intellectual impairment, seizures, ataxia, and paroxysmal laughter. The condition arises due to the loss of the maternally inherited copy of the gene in neurons. The paternally inherited allele is unable to compensate because it is silenced by the expression of an antisense transcript () on the paternal chromosome. , encoding enigmatic E3 ubiquitin ligase variants, regulates target proteins by either modifying their properties/functions or leading them to degradation through the proteasome. Over time, animal models, particularly the Knock-Out (KO) mice, have significantly contributed to our understanding of the molecular mechanisms underlying AS. However, a shift toward human pluripotent stem cell models (PSCs), such as human embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs), has gained momentum. These stem cell models accurately capture human genetic and cellular characteristics, offering an alternative or a complement to animal experimentation. Human stem cells possess the remarkable ability to recapitulate neurogenesis and generate "brain-in-a-dish" models, making them valuable tools for studying neurodevelopmental disorders like AS. In this review, we provide an overview of the current state-of-the-art human stem cell models of AS and explore their potential to become the preclinical models of choice for drug screening and development, thus propelling AS therapeutic advancements and improving the lives of affected individuals.
PubMed: 37928900
DOI: 10.3389/fcell.2023.1274040 -
Cureus Oct 2023Autosomal dominant intellectual development disorder-6 (MRD6) arises from a gene mutation, inducing neurodevelopmental issues. The effects of MRD6 encompass cognitive...
Autosomal Dominant Intellectual Development Disorder-6 (MRD6) Without Seizures Linked to a De Novo Mutation in the grin2b Gene Revealed by Exome Sequencing: A Case Report of a Moroccan Child.
Autosomal dominant intellectual development disorder-6 (MRD6) arises from a gene mutation, inducing neurodevelopmental issues. The effects of MRD6 encompass cognitive disabilities, seizures, muscle tone decline, and autism-like traits. Its severity ranges from mild impairment to severe epilepsy. The disorder's rarity is emphasized by roughly 100 reported GRIN2B-related cases, spotlighting the gene's significance in brain development. We present the case of a three-year-old Moroccan boy who was referred to a neuropediatric department for a molecular diagnosis. Initial genetic testing yielded inconclusive results, and subsequent tests for Angelman syndrome and metabolic diseases showed no abnormalities. Given the complexity of the disorder, exome sequencing was employed to identify the underlying genetic cause. Exome sequencing identified a nonsense (STOP) mutation c.3912C>G (p.Tyr1304Ter) in the gene in the heterozygous state known to be present in MRD6 (Online Mendelian Inheritance in Man (OMIM) 613970). The family segregation study shows that this is a de novo variant, which is confirmed by Sanger sequencing. This variant has not been previously reported in the GnomAD database. Based on current scientific knowledge, the variant is considered pathogenic (PVS1, PS2, PM2, PP3, PP5) according to the criteria of the American College of Medical Genetics and Genomics (ACMG). The mutation in the gene (p.Tyr1304Ter) was predicted to be deleterious through bioinformatics analysis tools. This study highlights the crucial role of the gene in normal brain development and communication within the nervous system. It also sheds light on the impact of a novel genetic mutation, identified through exome sequencing, on causing an intellectual developmental disorder in a child patient from Morocco.
PubMed: 37927744
DOI: 10.7759/cureus.46456 -
Scientific Reports Oct 2023Angelman syndrome (AS) is a rare neurogenetic disorder caused by UBE3A deficiency and characterized by severe developmental delay, cognitive impairment, and motor...
Angelman syndrome (AS) is a rare neurogenetic disorder caused by UBE3A deficiency and characterized by severe developmental delay, cognitive impairment, and motor dysfunction. In the present study, we performed RNA-seq on hippocampal samples from both wildtype (WT) and AS male mice, with or without contextual fear memory recall. There were 281 recall-associated differentially expressed genes (DEGs) in WT mice and 268 DEGs in AS mice, with 129 shared by the two genotypes. Gene ontology analysis showed that extracellular matrix and stimulation-induced response genes were prominently enriched in recall-associated DEGs in WT mice, while nuclear acid metabolism and tissue development genes were highly enriched in those from AS mice. Further analyses showed that the 129 shared DEGs belonged to nuclear acid metabolism and tissue development genes. Unique recall DEGs in WT mice were enriched in biological processes critical for synaptic plasticity and learning and memory, including the extracellular matrix network clustered around fibronectin 1 and collagens. In contrast, AS-specific DEGs were not enriched in any known pathways. These results suggest that memory recall in AS mice, while altering the transcriptome, fails to recruit memory-associated transcriptional programs, which could be responsible for the memory impairment in AS mice.
Topics: Mice; Male; Animals; Angelman Syndrome; Memory Disorders; Hippocampus; Fear; Memory
PubMed: 37903805
DOI: 10.1038/s41598-023-45769-x -
Molecular Syndromology Oct 2023is an instrumental protein in neuronal synaptic transmission in the brain, facilitating neurotransmitter release. It is encoded by the gene, and pathogenic variants in...
INTRODUCTION
is an instrumental protein in neuronal synaptic transmission in the brain, facilitating neurotransmitter release. It is encoded by the gene, and pathogenic variants in this gene cause neurodevelopmental features including early onset axial hypotonia, intellectual disability, and features of autism spectrum disorder. To date, only three types of allelic variants (loss of function, in-frame deletions, and missense variants) in the gene have been previously reported in 11 patients with learning difficulties. Here, we describe a patient in whom a novel de novo pathogenic variant in the gene was identified.
CASE PRESENTATION
A 15-month-old girl presented with early onset hypotonia, global developmental delay, learning difficulties, microcephaly, nystagmus, strabismus, and stereotypies. Later, she developed a sleep disorder, challenging behaviour with self-injury, and scoliosis. Gene agnostic analysis of whole genome sequencing data identified a novel de novo heterozygous missense variant c.197G>C (p.Arg66Pro) in the gene SNARE motif region.
DISCUSSION
This is the fourth report describing gene-related neurodevelopmental disorder. This report adds to the genotype-phenotype correlation and highlights this condition as an important differential diagnosis of Rett/Angelman-type spectrum of disorders. Patients presenting with features of either Rett syndrome or Angelman syndrome, in whom genetic testing is not suggestive, should be evaluated for variants in the gene, given the significant overlap in clinical presentation of these disorders.
PubMed: 37901860
DOI: 10.1159/000530150 -
Epilepsy Currents 2023
PubMed: 37901779
DOI: 10.1177/15357597231191885 -
MedRxiv : the Preprint Server For... Sep 2023Recurrent copy number variants (rCNVs) are associated with increased risk of neuropsychiatric disorders but their pathogenic population-level impact is unknown. We...
Recurrent copy number variants (rCNVs) are associated with increased risk of neuropsychiatric disorders but their pathogenic population-level impact is unknown. We provide population-based estimates of rCNV-associated risk of neuropsychiatric disorders for 34 rCNVs in the iPSYCH2015 case-cohort sample (n=120,247). Most observed significant increases in rCNV-associated risk for ADHD, autism or schizophrenia were moderate (HR:1.42-5.00), and risk estimates were highly correlated across these disorders, the most notable exception being high autism-associated risk with Prader-Willi/Angelman Syndrome duplications (HR=20.8). No rCNV was associated with significant increase in depression risk. Also, rCNV-associated risk was positively correlated with locus size and gene constraint. Comparison with published rCNV studies suggests that prevalence of some rCNVs is higher, and risk of psychiatric disorders lower, than previously estimated. In an era where genetics is increasingly being clinically applied, our results highlight the importance of population-based risk estimates for genetics-based predictions.
PubMed: 37886536
DOI: 10.1101/2023.09.04.23294975 -
Genetics in Medicine : Official Journal... Jan 2024Current and emerging treatments for Duchenne muscular dystrophy (DMD) position DMD as a candidate condition for newborn screening (NBS). In anticipation of the...
PURPOSE
Current and emerging treatments for Duchenne muscular dystrophy (DMD) position DMD as a candidate condition for newborn screening (NBS). In anticipation of the nomination of DMD for universal NBS, we conducted a prospective study under the Early Check voluntary NBS research program in North Carolina, United States.
METHODS
We performed screening for creatine kinase-MM (CK-MM), a biomarker of muscle damage, on residual routine newborn dried blood spots (DBS) from participating newborns. Total creatine kinase testing and next generation sequencing of an 86-neuromuscular gene panel that included DMD were offered to parents of newborns who screened positive. Bivariate and multivariable analyses were performed to assess effects of biological and demographic predictors on CK-MM levels in DBS.
RESULTS
We screened 13,354 newborns and identified 2 males with DMD. The provisional 1626 ng/mL cutoff was raised to 2032 ng/mL to improve specificity, and additional cutoffs (900 and 360 ng/mL) were implemented to improve sensitivity for older and low-birthweight newborns.
CONCLUSION
Population-scale screening for elevated CK-MM in DBS is a feasible approach to identify newborns with DMD. Inclusion of birthweight- and age-specific cutoffs, repeat creatine kinase testing after 72 hours of age, and DMD sequencing improve sensitivity and specificity of screening.
Topics: Male; Humans; Infant, Newborn; Muscular Dystrophy, Duchenne; Neonatal Screening; Birth Weight; North Carolina; Prospective Studies; Creatine Kinase
PubMed: 37864479
DOI: 10.1016/j.gim.2023.101009 -
Orphanet Journal of Rare Diseases Oct 2023Global disease registries are critical to capturing common patient related information on rare illnesses, allowing patients and their families to provide information...
Global disease registries are critical to capturing common patient related information on rare illnesses, allowing patients and their families to provide information about their condition in a safe, accessible, and engaging manner that enables researchers to undertake critical research aimed at improving outcomes. Typically, English is the default language of choice for these global digital health platforms. Unfortunately, language barriers can significantly inhibit participation from non-English speaking participants. In addition, there is potential for compromises in data quality and completeness. In contrast, multinational commercial entities provide access to their websites in the local language of the country they are operating in, and often provide multiple options reflecting ethnic diversity. This paper presents a case study of how the Global Angelman Syndrome Registry (GASR) has used a novel approach to enable multiple language translations for its website. Using a "semi-automated language translation" approach, the GASR, which was originally launched in English in September 2016, is now available in several other languages. In 2020, the GASR adopted a novel approach using crowd-sourcing and machine translation tools leading to the availability of the GASR in Spanish, Traditional Chinese, Italian, and Hindi. As a result, enrolments increased by 124% percent for Spain, 67% percent for Latin America, 46% percent for Asia, 24% for Italy, and 43% for India. We describe our approach here, which we believe presents an opportunity for cost-effective and timely translations responsive to changes to the registry and helps build and maintain engagement with global disease communities.
Topics: Humans; Angelman Syndrome; Language; Registries; Global Health; Asia
PubMed: 37858180
DOI: 10.1186/s13023-023-02904-1