Overexpression of miR-25 Downregulates the Expression of ROBO2 in Idiopathic Intellectual Disability.

Idiopathic intellectual disability (IID) encompasses the cases of intellectual disability (ID) without a known cause and represents approximately 50% of all cases. Neural progenitor cells (NPCs) from the olfactory neuroepithelium (NEO) contain the same information as the cells found in the brain, but they are more accessible. Some miRNAs have been identified and associated with ID of known etiology. However, in idiopathic ID, the effect of miRNAs is poorly understood. The aim of this study was to determine the miRNAs regulating the expression of mRNAs that may be involved in development of IID. Expression profiles were obtained using NPC-NEO cells from IID patients and healthy controls by microarray. A total of 796 miRNAs and 28,869 mRNAs were analyzed. Several miRNAs were overexpressed in the IID patients compared to controls. miR-25 had the greatest expression. In silico analysis showed that ROBO2 was the target for miR-25, with the highest specificity and being the most down-regulated. In vitro assay showed an increase of miR-25 expression induced a decrease in ROBO2 expression. In neurodevelopment, ROBO2 plays a crucial role in episodic learning and memory, so its down-regulation, caused by miR-25, could have a fundamental role in the intellectual disability that, until now, has been considered idiopathic.

Detection of autism spectrum disorder-related pathogenic trio variants by a novel structure-based approach.

BACKGROUND: Glutamatergic synapse dysfunction is believed to underlie the development of Autism Spectrum Disorder (ASD) and Intellectual Disability (ID) in many individuals. However, identification of genetic markers that contribute to synaptic dysfunction in these individuals is notoriously difficult. Based on genomic analysis, structural modeling, and functional data, we recently established the involvement of the TRIO-RAC1 pathway in ASD and ID. Furthermore, we identified a pathological de novo missense mutation hotspot in TRIO's GEF1 domain. ASD/ID-related missense mutations within this domain compromise glutamatergic synapse function and likely contribute to the development of ASD/ID. The number of ASD/ID cases with mutations identified within TRIO's GEF1 domain is increasing. However, tools for accurately predicting whether such mutations are detrimental to protein function are lacking. METHODS: Here we deployed advanced protein structural modeling techniques to predict potential de novo pathogenic and benign mutations within TRIO's GEF1 domain. Mutant TRIO-9 constructs were generated and expressed in CA1 pyramidal neurons of organotypic cultured hippocampal slices. AMPA receptor-mediated postsynaptic currents were examined in these neurons using dual whole-cell patch clamp electrophysiology. We also validated these findings using orthogonal co-immunoprecipitation and fluorescence lifetime imaging (FLIM-FRET) experiments to assay TRIO mutant overexpression effects on TRIO-RAC1 binding and on RAC1 activity in HEK293/T cells. RESULTS: Missense mutations in TRIO's GEF1 domain that were predicted to disrupt TRIO-RAC1 binding or stability were tested experimentally and found to greatly impair TRIO-9's influence on glutamatergic synapse function. In contrast, missense mutations in TRIO's GEF1 domain that were predicted to have minimal effect on TRIO-RAC1 binding or stability did not impair TRIO-9's influence on glutamatergic synapse function in our experimental assays. In orthogonal assays, we find most of the mutations predicted to disrupt binding display loss of function but mutants predicted to disrupt stability do not reflect our results from neuronal electrophysiological data. LIMITATIONS: We present a method to predict missense mutations in TRIO's GEF1 domain that may compromise TRIO function and test for effects in a limited number of assays. Possible limitations arising from the model systems employed here can be addressed in future studies. Our method does not provide evidence for whether these mutations confer ASD/ID risk or the likelihood that such mutations will result in the development of ASD/ID. CONCLUSIONS: Here we show that a combination of structure-based computational predictions and experimental validation can be employed to reliably predict whether missense mutations in the human TRIO gene impede TRIO protein function and compromise TRIO's role in glutamatergic synapse regulation. With the growing accessibility of genome sequencing, the use of such tools in the accurate identification of pathological mutations will be instrumental in diagnostics of ASD/ID.

Recurrent myocardial injury in a de novo SON mutation ZTTK syndrome patient: a case report.

BACKGROUND: Zhu-Tokita-Takenouchi-Kim syndrome (ZTTK syndrome) is a severe multi-systemic developmental disorder, caused by variants in the SON gene. A patient diagnosed with ZTTK syndrome who carried a de novo SON mutation and exhibited recurrent myocardial injury was described in this case. CASE PRESENTATION: A 7-year-old girl was admitted to the Cardiology Department of Beijing Children's Hospital in November 2019 due to myocardial injury following respiratory infection. She displayed elevated myocardial enzymes and severe T-wave changes on electrocardiogram. Over the past three years, she had experienced myocardial injury on three occasions. Additionally, she exhibited intellectual disability, congenital amblyopia, and dysmorphic facial features. Genetic analysis revealed a de novo heterozygous mutation c.3852_3856delGGTAT in the SON gene, which was confirmed by Sanger sequencing of her parents. She received anti-infection treatment and was administered metoprolol orally. Her condition was stable at the time of discharge. Over a 42-month follow-up period at the outpatient clinic, she complained intermittent fatigue and palpitation. CONCLUSIONS: The identified SON mutation, which plays a crucial role in heart development and mitochondrial function, may be associated with an increased susceptibility to myocardial injury or cardiomyopathy. This case report contributes novel insights into this rare condition and suggests the expansion of the ZTTK syndrome phenotype.

Increasing histone acetylation improves sociability and restores learning and memory in KAT6B-haploinsufficient mice.

Mutations in genes encoding chromatin modifiers are enriched among mutations causing intellectual disability. The continuing development of the brain postnatally, coupled with the inherent reversibility of chromatin modifications, may afford an opportunity for therapeutic intervention following a genetic diagnosis. Development of treatments requires an understanding of protein function and models of the disease. Here, we provide a mouse model of Say-Barber-Biesecker-Young-Simpson syndrome (SBBYSS) (OMIM 603736) and demonstrate proof-of-principle efficacy of postnatal treatment. SBBYSS results from heterozygous mutations in the KAT6B (MYST4/MORF/QFK) gene and is characterized by intellectual disability and autism-like behaviors. Using human cells carrying SBBYSS-specific KAT6B mutations and Kat6b heterozygous mice (Kat6b+/-), we showed that KAT6B deficiency caused a reduction in histone H3 lysine 9 acetylation. Kat6b+/- mice displayed learning, memory, and social deficits, mirroring SBBYSS individuals. Treatment with a histone deacetylase inhibitor, valproic acid, or an acetyl donor, acetyl-carnitine (ALCAR), elevated histone acetylation levels in the human cells with SBBYSS mutations and in brain and blood cells of Kat6b+/- mice and partially reversed gene expression changes in Kat6b+/- cortical neurons. Both compounds improved sociability in Kat6b+/- mice, and ALCAR treatment restored learning and memory. These data suggest that a subset of SBBYSS individuals may benefit from postnatal therapeutic interventions.

A novel variant in NSUN2 causes intellectual disability in a Chinese family.

NSUN2-intellectual disability syndrome, also known as intellectual disability type 5 (MRT5), is an autosomal recessive disorder that is characterized by intellectual disability (ID), postnatal growth retardation, dysmorphic facies, microcephaly, short stature, developmental delay, language impairment and other congenital abnormalities. The disease is caused by mutations in the NSUN2 gene, which encodes a tRNA cytosine methyltransferase that has an important role in spindle assembly during mitosis and chromosome segregation. In this study, we recruited a family that had two individuals with ID. Whole exome sequencing was performed to identify a homozygous frameshift variant (c.1171_1175delACCAT(p.Thr391fs*18*)) in NSUN2 (NM_017755.5) in the proband. The varint was confirmed as segregating in his affected brother and his parents by Sanger sequencing. The individuals that we described showed a similar dysmorphology profile to that associated with MRT5. To analyze the correlations between genotypes of NSUN2 and phenotypes of individuals with ID, we examined 17 variants and the associated phenotypes from 32 ID individuals in current and previous studies. We concluded that mutations in NSUN2 cause a wide range of phenotypic defects. Although some clinical manifestations were highly variable, the core phenotypes associated with NSUN2 mutations were dysmorphic facies, microcephaly, short stature, ID, growth restriction, language impairment, hypotonia and delayed puberty. Our study expands the genetic spectrum of NSUN2 mutations and helps to further define the genotype-phenotype correlations in MRT5.

Shared and divergent mental health characteristics of ADNP-, CHD8- and DYRK1A-related neurodevelopmental conditions.

BACKGROUND: Neurodevelopmental conditions such as intellectual disability (ID) and autism spectrum disorder (ASD) can stem from a broad array of inherited and de novo genetic differences, with marked physiological and behavioral impacts. We currently know little about the psychiatric phenotypes of rare genetic variants associated with ASD, despite heightened risk of psychiatric concerns in ASD more broadly. Understanding behavioral features of these variants can identify shared versus specific phenotypes across gene groups, facilitate mechanistic models, and provide prognostic insights to inform clinical practice. In this paper, we evaluate behavioral features within three gene groups associated with ID and ASD - ADNP, CHD8, and DYRK1A - with two aims: (1) characterize phenotypes across behavioral domains of anxiety, depression, ADHD, and challenging behavior; and (2) understand whether age and early developmental milestones are associated with later mental health outcomes. METHODS: Phenotypic data were obtained for youth with disruptive variants in ADNP, CHD8, or DYRK1A (N = 65, mean age = 8.7 years, 40% female) within a long-running, genetics-first study. Standardized caregiver-report measures of mental health features (anxiety, depression, attention-deficit/hyperactivity, oppositional behavior) and developmental history were extracted and analyzed for effects of gene group, age, and early developmental milestones on mental health features. RESULTS: Patterns of mental health features varied by group, with anxiety most prominent for CHD8, oppositional features overrepresented among ADNP, and attentional and depressive features most prominent for DYRK1A. For the full sample, age was positively associated with anxiety features, such that elevations in anxiety relative to same-age and same-sex peers may worsen with increasing age. Predictive utility of early developmental milestones was limited, with evidence of early language delays predicting greater difficulties across behavioral domains only for the CHD8 group. CONCLUSIONS: Despite shared associations with autism and intellectual disability, disruptive variants in ADNP, CHD8, and DYRK1A may yield variable psychiatric phenotypes among children and adolescents. With replication in larger samples over time, efforts such as these may contribute to improved clinical care for affected children and adolescents, allow for earlier identification of emerging mental health difficulties, and promote early intervention to alleviate concerns and improve quality of life.

Dodecyl creatine ester therapy: from promise to reality.

Pathogenic variants in SLC6A8, the gene which encodes creatine transporter SLC6A8, prevent creatine uptake in the brain and result in a variable degree of intellectual disability, behavioral disorders (e.g., autism spectrum disorder), epilepsy, and severe speech and language delay. There are no treatments to improve neurodevelopmental outcomes for creatine transporter deficiency (CTD). In this spotlight, we summarize recent advances in innovative molecules to treat CTD, with a focus on dodecyl creatine ester, the most promising drug candidate.

ADNP dysregulates methylation and mitochondrial gene expression in the cerebellum of a Helsmoortel-Van der Aa syndrome autopsy case.

BACKGROUND: Helsmoortel-Van der Aa syndrome is a neurodevelopmental disorder in which patients present with autism, intellectual disability, and frequent extra-neurological features such as feeding and gastrointestinal problems, visual impairments, and cardiac abnormalities. All patients exhibit heterozygous de novo nonsense or frameshift stop mutations in the Activity-Dependent Neuroprotective Protein (ADNP) gene, accounting for a prevalence of 0.2% of all autism cases worldwide. ADNP fulfills an essential chromatin remodeling function during brain development. In this study, we investigated the cerebellum of a died 6-year-old male patient with the c.1676dupA/p.His559Glnfs*3 ADNP mutation. RESULTS: The clinical presentation of the patient was representative of the Helsmoortel-Van der Aa syndrome. During his lifespan, he underwent two liver transplantations after which the child died because of multiple organ failure. An autopsy was performed, and various tissue samples were taken for further analysis. We performed a molecular characterization of the cerebellum, a brain region involved in motor coordination, known for its highest ADNP expression and compared it to an age-matched control subject. Importantly, epigenome-wide analysis of the ADNP cerebellum identified CpG methylation differences and expression of multiple pathways causing neurodevelopmental delay. Interestingly, transcription factor motif enrichment analysis of differentially methylated genes showed that the ADNP binding motif was the most significantly enriched. RNA sequencing of the autopsy brain further identified downregulation of the WNT signaling pathway and autophagy defects as possible causes of neurodevelopmental delay. Ultimately, label-free quantification mass spectrometry identified differentially expressed proteins involved in mitochondrial stress and sirtuin signaling pathways amongst others. Protein-protein interaction analysis further revealed a network including chromatin remodelers (ADNP, SMARCC2, HDAC2 and YY1), autophagy-related proteins (LAMP1, BECN1 and LC3) as well as a key histone deacetylating enzyme SIRT1, involved in mitochondrial energy metabolism. The protein interaction of ADNP with SIRT1 was further biochemically validated through the microtubule-end binding proteins EB1/EB3 by direct co-immunoprecipitation in mouse cerebellum, suggesting important mito-epigenetic crosstalk between chromatin remodeling and mitochondrial energy metabolism linked to autophagy stress responses. This is further supported by mitochondrial activity assays and stainings in patient-derived fibroblasts which suggest mitochondrial dysfunctions in the ADNP deficient human brain. CONCLUSION: This study forms the baseline clinical and molecular characterization of an ADNP autopsy cerebellum, providing novel insights in the disease mechanisms of the Helsmoortel-Van der Aa syndrome. By combining multi-omic and biochemical approaches, we identified a novel SIRT1-EB1/EB3-ADNP protein complex which may contribute to autophagic flux alterations and impaired mitochondrial metabolism in the Helsmoortel-Van der Aa syndrome and holds promise as a new therapeutic target.

Genetic analysis of a child with severe intellectual disability caused by a novel variant in the FERM domain of the FRMPD4 protein.

Intellectual developmental disorder, X-linked 104 (XLID104), caused by the FRMPD4 gene variant, is a rare X-linked genetic disease that primarily manifests as intellectual disability (ID) and language delay, and may be accompanied by behavioural abnormalities. Currently, only 11 patients from four families have been reported to carry FRMPD4 gene variants. Here, we report a rare case of a Chinese patient with XLID104 who was presented with severe ID and language impairment. Genetic testing results showed that the patient had a novel hemizygous variant on FRMPD4 inherited from the heterozygous variant NM_001368397: c.1772A>C (p.Glu591Ala) carried by his mother. To our knowledge, this variant has not been reported previously. Western blot results for the recombinant plasmid constructed in vitro indicated that the expression of the mutant protein may be reduced. Using molecular dynamics simulations, we predicted that the mutant protein may affect the interaction of the FRMPD4 protein with DLG4. In this study, we expand the spectrum of FRMPD4 variants and suggest that the clinical awareness of the genetic diagnosis of nonsyndromic ID should be strengthened.

Atypical mandibulofacial dysostosis with microcephaly diagnosed through the identification of a novel pathogenic mutation in EFTUD2.

BACKGROUND: Mandibulofacial dysostosis with microcephaly (MFDM, OMIM# 610536) is a rare monogenic disease that is caused by a mutation in the elongation factor Tu GTP binding domain containing 2 gene (EFTUD2, OMIM* 603892). It is characterized by mandibulofacial dysplasia, microcephaly, malformed ears, cleft palate, growth and intellectual disability. MFDM can be easily misdiagnosed due to its phenotypic overlap with other craniofacial dysostosis syndromes. The clinical presentation of MFDM is highly variable among patients. METHODS: A patient with craniofacial anomalies was enrolled and evaluated by a multidisciplinary team. To make a definitive diagnosis, whole-exome sequencing was performed, followed by validation by Sanger sequencing. RESULTS: The patient presented with extensive facial bone dysostosis, upward slanting palpebral fissures, outer and middle ear malformation, a previously unreported orbit anomaly, and spina bifida occulta. A novel, pathogenic insertion mutation (c.215_216insT: p.Tyr73Valfs*4) in EFTUD2 was identified as the likely cause of the disease. CONCLUSIONS: We diagnosed this atypical case of MFDM by the detection of a novel pathogenetic mutation in EFTUD2. We also observed previously unreported features. These findings enrich both the genotypic and phenotypic spectrum of MFDM.

[Analysis of clinical characteristics and molecular genetics in eighteen patients with 1q21.1 microdeletion syndrome].

OBJECTIVE: To explore the clinical characteristics of 1q21.1 microdeletion by using single nucleotide polymorphism microarrays (SNP array). METHODS: Eighteen cases of 1q21.1 microdeletion syndrome diagnosed at the Longgang District Maternal and Child Health Care Hospital of Shenzhen City from June 2017 to December 2022 were selected as the study subjects. Clinical data of the patients were collected. Results of chromosomal karyotyping and SNP assay were retrospectively analyzed. RESULTS: Among the 18 cases with 1q21.1 microdeletions, 13 had a deletion between BP3 and BP4, 4 had a deletion between BP1/BP2 and BP4, whilst 1 had a proximal 1q21.1 deletion (between BP2 and BP3) involving the Thrombocytopenia-absent radius (TAR) region. The deletions had spanned from 360 kb to 3.9 Mb, which encompassed the GJA5, GJA8, CHD1L, RBM8AB and other morbid genes. In three families, the proband child has inherited the same 1q21.1 microdeletion from their parents, whose clinical phenotype was normal or slightly abnormal. The clinical phenotypes of 1q21.1 microdeletion had included cognitive or behavioral deficits in 9 cases (9/18, 50.0%), growth retardation in 8 cases (8/18, 44.4%), craniofacial deformities in 7 cases (7/18, 38.8%), cardiovascular malformations in 5 cases (5/18, 27.8%), and microcephaly in 3 cases (3/18, 16.7%). CONCLUSION: 1q21.1 microdeletion syndrome has incomplete penetrance and varied expression such as intellectual impairment, growth and development delay, and microcephaly, with a wide range of non-specific phenotypes.

Disrupted protein interaction dynamics in a genetic neurodevelopmental disorder revealed by structural bioinformatics and genetic code expansion.

Deciphering the structural effects of gene variants is essential for understanding the pathophysiological mechanisms of genetic diseases. Using a neurodevelopmental disorder called Bosch-Boonstra-Schaaf Optic Atrophy Syndrome (BBSOAS) as a genetic disease model, we applied structural bioinformatics and Genetic Code Expansion (GCE) strategies to assess the pathogenic impact of human NR2F1 variants and their binding with known and novel partners. While the computational analyses of the NR2F1 structure delineated the molecular basis of the impact of several variants on the isolated and complexed structures, the GCE enabled covalent and site-specific capture of transient supramolecular interactions in living cells. This revealed the variable quaternary conformations of NR2F1 variants and highlighted the disrupted interplay with dimeric partners and the newly identified co-factor, CRABP2. The disclosed consequence of the pathogenic mutations on the conformation, supramolecular interplay, and alterations in the cell cycle, viability, and sub-cellular localization of the different variants reflect the heterogeneous disease spectrum of BBSOAS and set up novel foundation for unveiling the complexity of neurodevelopmental diseases.

Chromosomal Duplication Syndromes: A Case Series.

Chromosomal deletion and duplication syndromes can lead to intellectual disability, autism, microcephaly, and poor growth. Usually manifestations of duplication syndromes are milder than that of the deletion syndromes. With the availability of tests for analysis of copy number variants, it is possible to identify the deletion and duplication syndromes with greater ease. We report 32 cases of chromosomal duplication syndromes, identified in children presenting with developmental delay, intellectual disability, or microcephaly and/or additional features, at a tertiary care center on karyotyping or microarray analysis. Seven were isolated duplications, and one child had an additional smaller pathogenic deletion. Thus, duplication syndromes can have milder presentations with spectrum of dysmorphism, behavioral problems, and intellectual disability, but it is possible to diagnose easily with latest emerging high-throughput technologies.

PHF6-mediated transcriptional control of NSC via Ephrin receptors is impaired in the intellectual disability syndrome BFLS.

The plant homeodomain zinc-finger protein, PHF6, is a transcriptional regulator, and PHF6 germline mutations cause the X-linked intellectual disability (XLID) Börjeson-Forssman-Lehmann syndrome (BFLS). The mechanisms by which PHF6 regulates transcription and how its mutations cause BFLS remain poorly characterized. Here, we show genome-wide binding of PHF6 in the developing cortex in the vicinity of genes involved in central nervous system development and neurogenesis. Characterization of BFLS mice harbouring PHF6 patient mutations reveals an increase in embryonic neural stem cell (eNSC) self-renewal and a reduction of neural progenitors. We identify a panel of Ephrin receptors (EphRs) as direct transcriptional targets of PHF6. Mechanistically, we show that PHF6 regulation of EphR is impaired in BFLS mice and in conditional Phf6 knock-out mice. Knockdown of EphR-A phenocopies the PHF6 loss-of-function defects in altering eNSCs, and its forced expression rescues defects of BFLS mice-derived eNSCs. Our data indicate that PHF6 directly promotes Ephrin receptor expression to control eNSC behaviour in the developing brain, and that this pathway is impaired in BFLS.

A novel variant in ASNS gene responsible for syndromic intellectual disability and microcephaly: Case report and literature review.

BACKGROUND: The ASNS (ASNS, MIM 108370) gene variations are responsible for asparagine synthetase deficiency (ASNSD, MIM 615574), a very rare autosomal recessive disease characterized by cerebral anomalies. These patients have congenital microcephaly, progressive encephalopathy, severe intellectual disability, and intractable seizures. METHOD: Clinical characteristics of the patient were collected. Exome sequencing was used for the identification of variants. Sanger sequencing was used to confirm the variant in the target region. The structure of the protein was checked using the DynaMut2 web server. RESULTS: The proband is an 11-year-old Iranian-Azeri girl with primary microcephaly and severe intellectual disability in a family with a consanguineous marriage. Symptoms emerged around the 10-20th days of life, when refractory epileptic gaze and unilateral tonic-clonic seizures initiated without any provoking factor such as fever. A brain MRI revealed no abnormalities except for brain atrophy. The karyotype was normal. Using exome sequencing, we identified a novel homozygous variant of thymine to adenine (NM_001673.5:c.538T>A) in the ASNS gene. Both parents had a heterozygous variant in this location. Subsequently, Sanger sequencing confirmed this variant. We also reviewed the clinical manifestations and MRI findings of the previously reported patients. CONCLUSION: In the present study, a novel homozygous variant was recognized in the ASNS gene in an Iranian-Azeri girl manifesting typical ASNSD symptoms, particularly intellectual disability and microcephaly. This study expands the mutation spectrum of ASNSD and reviews previously reported patients.

Genetic determinants of global developmental delay and intellectual disability in Ukrainian children.

BACKGROUND: Global developmental delay or intellectual disability usually accompanies various genetic disorders as a part of the syndrome, which may include seizures, autism spectrum disorder and multiple congenital abnormalities. Next-generation sequencing (NGS) techniques have improved the identification of pathogenic variants and genes related to developmental delay. This study aimed to evaluate the yield of whole exome sequencing (WES) and neurodevelopmental disorder gene panel sequencing in a pediatric cohort from Ukraine. Additionally, the study computationally predicted the effect of variants of uncertain significance (VUS) based on recently published genetic data from the country's healthy population. METHODS: The study retrospectively analyzed WES or gene panel sequencing findings of 417 children with global developmental delay, intellectual disability, and/or other symptoms. Variants of uncertain significance were annotated using CADD-Phred and SIFT prediction scores, and their frequency in the healthy population of Ukraine was estimated. RESULTS: A definitive molecular diagnosis was established in 66 (15.8%) of the individuals. WES diagnosed 22 out of 37 cases (59.4%), while the neurodevelopmental gene panel identified 44 definitive diagnoses among the 380 tested patients (12.1%). Non-diagnostic findings (VUS and carrier) were reported in 350 (83.2%) individuals. The most frequently diagnosed conditions were developmental and epileptic encephalopathies associated with severe epilepsy and GDD/ID (associated genes ARX, CDKL5, STXBP1, KCNQ2, SCN2A, KCNT1, KCNA2). Additionally, we annotated 221 VUS classified as potentially damaging, AD or X-linked, potentially increasing the diagnostic yield by 30%, but 18 of these variants were present in the healthy population of Ukraine. CONCLUSIONS: This is the first comprehensive study on genetic causes of GDD/ID conducted in Ukraine. This study provides the first comprehensive investigation of the genetic causes of GDD/ID in Ukraine. It presents a substantial dataset of diagnosed genetic conditions associated with GDD/ID. The results support the utilization of NGS gene panels and WES as first-line diagnostic tools for GDD/ID cases, particularly in resource-limited settings. A comprehensive approach to resolving VUS, including computational effect prediction, population frequency analysis, and phenotype assessment, can aid in further reclassification of deleterious VUS and guide further testing in families.

The Healthcare and Societal Costs of Familial Intellectual Disability.

Most of the studies on the cost of intellectual disability are limited to a healthcare perspective or cohorts composed of individuals where the etiology of the condition is a mixture of genetic and non-genetic factors. When used in policy development, these can impact the decisions made on the optimal allocation of resources. In our study, we have developed a static microsimulation model to estimate the healthcare, societal, and lifetime cost of individuals with familial intellectual disability, an inheritable form of the condition, to families and government. The results from our modeling show that the societal costs outweighed the health costs (approximately 89.2% and 10.8%, respectively). The lifetime cost of familial intellectual disability is approximately AUD 7 million per person and AUD 10.8 million per household. The lifetime costs to families are second to those of the Australian Commonwealth government (AUD 4.2 million and AUD 9.3 million per household, respectively). These findings suggest that familial intellectual disability is a very expensive condition, representing a significant cost to families and government. Understanding the drivers of familial intellectual disability, especially societal, can assist us in the development of policies aimed at improving health outcomes and greater access to social care for affected individuals and their families.

Initial clinical and molecular investigation of 20q13.33 microdeletion with 17q25.3/14q32.31q32.33 microduplication in Chinese pediatric patients.

BACKGROUND: Limited research has been conducted regarding the elucidation of genotype-phenotype correlations within the 20q13.33 region. The genotype-phenotype association of 20q13.33 microdeletion remains inadequately understood. In the present study, two novel cases of 20q13.33 microdeletion were introduced, with the objective of enhancing understanding of the genotype-phenotype relationship. METHODS: Two unrelated patients with various abnormal clinical phenotypes from Fujian province Southeast China were enrolled in the present study. Karyotype analysis and chromosomal microarray analysis (CMA) were performed to investigate chromosomal abnormalities and copy number variants. RESULTS: The results of high-resolution G-banding karyotype analysis elicited a 46,XY,der(20)add(20)(q13.3) in Patient 1. This patient exhibited various clinical manifestations, such as global developmental delay, intellectual disability, seizures, and other congenital diseases. Subsequently, a 1.0-Mb deletion was identified in the 20q13.33 region alongside a 5.2-Mb duplication in the 14q32.31q32.33 region. In Patient 2, CMA results revealed a 1.8-Mb deletion in the 20q13.33 region with a 4.8-Mb duplication of 17q25.3. The patient exhibited additional abnormal clinical features, including micropenis, congenital heart disease, and a distinctive crying pattern characterized by a crooked mouth. CONCLUSION: In the present study, for the first time, an investigation was conducted into two novel cases of 20q13.33 microdeletion with microduplications in the 17q25.3 and 14q32.31q32.33 regions in the Chinese population. The presence of micropenis may be attributed to the 20q13.33 microdeletion, potentially expanding the phenotypic spectrum associated with this deletion.

Deciphering congenital heart defects, facial dysmorphism and intellectual developmental disorder (CHDFIDD) associated with constitutional CDK13 pathogenic variants - case report and literature review.

There are 21 human cyclin-dependent kinases which are involved in regulation of the cell cycle, transcription, RNA splicing, apoptosis and neurogenesis. Five of them: CDK4, CDK5, CDK6, CDK10 and CDK13 are associated with human phenotypes. To date, only 62 patients have been presented with mutated CDK13 gene. Those patients had developmental delay, dysmorphic facial features, feeding difficulties, different structural heart and brain defects. 36 of them had missense mutation affecting the protein kinase domain of CDK13. Our patient is the first person reported so far with a frameshift mutation which introduce premature stop codon in the first exon of the CDK13 gene. She has symptoms characteristic for congenital heart defects, facial dysmorphism and intellectual developmental disorder (CHDFIDD).

Mowat-Wilson Syndrome: Case Report and Review of ZEB2 Gene Variant Types, Protein Defects and Molecular Interactions.

Mowat-Wilson syndrome (MWS) is a rare genetic neurodevelopmental congenital disorder associated with various defects of the zinc finger E-box binding homeobox 2 (ZEB2) gene. The ZEB2 gene is autosomal dominant and encodes six protein domains including the SMAD-binding protein, which functions as a transcriptional corepressor involved in the conversion of neuroepithelial cells in early brain development and as a mediator of trophoblast differentiation. This review summarizes reported ZEB2 gene variants, their types, and frequencies among the 10 exons of ZEB2. Additionally, we summarized their corresponding encoded protein defects including the most common variant, c.2083 C>T in exon 8, which directly impacts the homeodomain (HD) protein domain. This single defect was found in 11% of the 298 reported patients with MWS. This review demonstrates that exon 8 encodes at least three of the six protein domains and accounts for 66% (198/298) of the variants identified. More than 90% of the defects were due to nonsense or frameshift changes. We show examples of protein modeling changes that occurred as a result of ZEB2 gene defects. We also report a novel pathogenic variant in exon 8 in a 5-year-old female proband with MWS. This review further explores other genes predicted to be interacting with the ZEB2 gene and their predicted gene-gene molecular interactions with protein binding effects on embryonic multi-system development such as craniofacial, spine, brain, kidney, cardiovascular, and hematopoiesis.