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At least 19 recordsLinked to original sources

Reduced auditory M100 asymmetry in schizophrenia and dyslexia: applying a developmental instability approach to assess atypical brain asymmetry.

Although atypical structural and functional superior temporal gyrus (STG) asymmetries are frequently observed in patients with schizophrenia and individuals with dyslexia, their significance is unclear. One possibility is that atypical asymmetries reflect a general risk factor that can be seen across multiple neurodevelopmental conditions--a risk factor whose origins are best understood in the context of Developmental Instability (DI) theory. DI measures (minor physical anomalies (MPAs) and fluctuating asymmetries (FAs)) reflect perturbation of the genetic plan. The present study sought to assess whether the presence of peripheral indices of DI predicts anomalous functional auditory cortex asymmetry in schizophrenia patients and dyslexia subjects. The location of the auditory M100 response was used as a measure of functional STG asymmetry, as it has been reported that in controls (but not in subjects with schizophrenia or dyslexia) the M100 source location in the right hemisphere is shifted anterior to that seen for the left hemisphere. Whole-brain auditory evoked magnetic field data were successfully recorded from 14 male schizophrenia patients, 21 male subjects with dyslexia, and 16 normal male control subjects. MPA and FA measures were also obtained. Replicating previous studies, both schizophrenia and dyslexia groups showed less M100 asymmetry than did controls. Schizophrenia and dyslexia subjects also had higher MPA scores than normal controls. Although neither total MPA nor FA measures predicted M100 asymmetry, analyses on individual MPA items revealed a relationship between high palate and M100 asymmetry. Findings suggest that M100 positional asymmetry is not a diagnostically specific feature in several neurodevelopmental conditions. Continued research examining DI and brain asymmetry relationships is warranted.

Adult↗

Antibodies to neuronal targets in neurological and psychiatric diseases.

The role of antibodies to specific neuronal and muscle ion channels in the etiology of neuromuscular transmission disorders is now well accepted. In addition, maternal antibodies can cross the placenta and cause neonatal disease or even alter the development of the infant, raising the possibility that some neurodevelopmental conditions could be caused by maternal antibodies. Voltage-gated ion channels are expressed in the brain as well as at the neuromuscular junction, and in recent years it has become clear that antibodies to some central nervous system (CNS) channels can be associated with CNS disease. This review highlights features of these conditions, preliminary investigations into neurodevelopmental disorders, and areas for further study.

Antibodies↗

Long-chain polyunsaturated fatty acids and neurological developmental outcome at 18 months in healthy term infants.

AIM: Previously, we found a beneficial effect of 2 mo supplementation of infant formula with long-chain polyunsaturated fatty acids (LC-PUFA) on neurological condition at 3 mo in healthy term infants. The aim of the present follow-up study was to evaluate whether the effect on neurological condition persists until 18 mo. METHODS: A prospective, double-blind, randomized control study was conducted. Three groups were formed: a control (CF; n = 169), an LC-PUFA-supplemented (LF; n = 146) and a breastfed (BF; n = 159) group. Information on potential confounders was collected at enrolment. At the age of 18 mo, neurodevelopmental condition was assessed by the age-specific neurological examination of Hempel and the Bayley scales. The Hempel assessment resulted in a clinical neurological diagnosis, a total optimality score and a score on the fluency of motility. The Bayley scales resulted in mental and psychomotor developmental indices. Attrition at 18 mo was 5.5% and non-selective. Multivariate regression analyses were carried out to evaluate the effect of type of feeding while adjusting for confounders. RESULTS: None of the children had developed cerebral palsy and 23 (CF: n = 8; LF: n = 10; BF: n = 5) showed minor neurological dysfunction. The groups did not show statistically significant differences in clinical neurological condition, neurological optimality score, fluency score, and the psychomotor and mental development indices. Multivariate analysis confirmed that there was no effect of type of feeding on neurological condition. CONCLUSION: This study indicates that the beneficial neurodevelopmental effect of 2 mo LC-PUFA supplementation in healthy term infants can not be detected at the age of 18 mo.

Age Factors↗

Prenatal BPA exposure perturbs RNA-binding protein-mediated splicing regulation and synaptogenesis in the developing cerebellum in a sex-dependent manner.

BACKGROUND: Autism spectrum disorder (ASD) is a pervasive neurodevelopmental condition characterized by social communication deficits, exhibiting a male bias in prevalence. Emerging evidence suggests that prenatal exposure to bisphenol A (BPA) may perturb neurodevelopmental trajectories relevant to ASD. While the cerebellum is increasingly recognized as a brain region implicated in ASD pathophysiology, the impact of gestational BPA exposure on its post-transcriptional alternative splicing machinery remains fundamentally undefined. METHODS: Here, we investigated sex-dependent effects of prenatal BPA exposure on the alternative splicing landscape of the neonatal rat cerebellum. We utilized RNA-seq to profile differential alternative splicing (DAS) events. Ingenuity Pathway Analysis (IPA) was used to predict biological functions and canonical pathways, and to construct the interactome network of DAS genes. To explore candidate upstream regulatory mechanisms, we performed in silico molecular docking and used high-resolution melting (HRM) qRT-PCR to validate selected splicing events. Furthermore, we assessed in vitro cellular phenotypes in primary cerebellar neurons by measuring MTS-based viability and Syn1/Psd95 puncta colocalization. RESULTS: Prenatal BPA exposure was associated with widespread DAS in genes enriched for ASD-relevant pathways in the neonatal rat cerebellum. To our knowledge, this study is the first to report molecular docking analyses predicting favorable interactions between BPA and several candidate RNA-binding proteins (RBPs), including CPEB1, RALYL, HNRNPDL, and ACO1. Our findings support a model in which BPA may perturb RBP-associated splicing regulation, including altered splicing of chromatin regulators such as Ccar1 in males. These molecular and cellular findings were accompanied by sex-stratified differences in neuronal viability and synaptic puncta measurements. BPA exposure was associated with an increased MTS viability signal in male primary cerebellar neurons, together with significant reductions in Psd95 and Syn1 puncta density, whereas female neurons showed significantly increased synaptic puncta colocalization together with reduced viability. CONCLUSIONS: In this study, we propose that prenatal BPA may be relevant to ASD-related neurodevelopmental pathways through sex-dependent changes in RBP-associated alternative splicing, including altered splicing of Ccar1 in males, together with distinct cellular outcomes. Together, these findings identify the developing cerebellum as a sensitive target of prenatal BPA exposure and highlight alternative splicing as a candidate pathway relevant to ASD biology.

Animals↗

Cell-type-specific DNA methylation dynamics in the prenatal and postnatal human cortex.

The human cortex undergoes extensive epigenetic remodeling during development, although the precise temporal and cell-type-specific dynamics of DNA methylation remain incompletely understood. In this study, we profiled genome-wide DNA methylation across human cortex tissue from donors aged 6 post-conception weeks to 108 years of age. We observed widespread, developmentally regulated changes in DNA methylation, with pronounced shifts occurring during early- and mid-gestation that were distinct from age-associated modifications in the postnatal cortex. Using fluorescence-activated nuclei sorting, we optimized a protocol for the isolation of SATB2-positive neuronal nuclei, enabling the identification of cell-type-specific DNA methylation trajectories in the developing cortex. Developmentally dynamic DNA methylation sites were significantly enriched near genes implicated in autism and schizophrenia, supporting a role for epigenetic dysregulation in neurodevelopmental conditions. Our findings underscore the prenatal period as a critical window of epigenomic plasticity in the brain with important implications for understanding the genetic basis of neurodevelopmental phenotypes.

Humans↗

Red blood cell fatty acid compositions in a patient with autistic spectrum disorder: a characteristic abnormality in neurodevelopmental disorders?

The fatty acid compositions of red blood cell (RBC) phospholipids from a patient with autistic spectrum disorder (ASD) had reduced percentages of highly unsaturated fatty acids (HUFA) compared to control samples. The percentage of HUFA in the RBC from the autistic patient was dramatically reduced (up to 70%) when the sample was stored for 6 weeks at -20 degrees C. However, only minor HUFA reductions were recorded in control samples stored similarly, or when the autistic sample was stored at -80 degrees C. A similar instability in RBC HUFA compositions upon storage at -20 degrees C has been recorded in schizophrenic patients. In a number of other neurodevelopmental conditions, including attention deficit hyperactivity disorder (ADHD) and dyslexia, reduced concentrations of RBC HUFA have been recorded. The extent and nature of these aberrations require further assessment to determine a possible common biochemical origin of neurodevelopmental disorders in general. To facilitate this, a large scale assessment of RBC fatty acid compositions in patients with ASD, and related disorders, should be performed as a matter of urgency. Supplementing cells in culture with the tryptophan metabolite indole acrylic acid (IAA) affected the levels of cellular HUFA and prostaglandin production. Indole acroyl glycine (IAG), a metabolite of IAA excreted in urine, is found in high concentrations in patients with neurodevelopmental disorders including ASD, ADHD, dyslexia, Asperger's syndrome and obsessive compulsive disorder.

Asperger Syndrome↗

Hearing and language in preschool very low birthweight children.

To get more insight into preschool language and hearing in high-risk very low birthweight (VLBW) children, we conducted a prospective study in a cohort of 79 children. The prevalence of language impairment and hearing loss at age 3-4 years, their relationship to each other as well as to perinatal conditions, neurodevelopmental outcome and the home environment are described. Mild hearing loss was found in 26%, moderate hearing loss in 13% and severe hearing loss in 3% of the children. None of the children was deaf. Abnormal tympanometry was found in 57% of the children. Hearing loss at age 4 years was related to a less optimal neonatal condition and was not related to the obstetrical condition or to neonatal cerebral ultrasound findings. Language impairment was found in 21% of the children at age 3.6 years. Receptive and expressive language was not related to perinatal conditions. There was no relation between the language assessments and the audiological assessments. Cognition and the home environment of the child were the only independent variables in the prediction of language in preschool VLBW children.

Audiometry, Evoked Response↗

Cerebral palsy-definition, classification, etiology and early diagnosis.

Cerebral palsy is a common neurodevelopmental condition encountered by pediatricians. The condition may present itself in many different clinical spectra. The etiological and risk factors are many and an awareness of the interplay of multiple factors in the causation of CP is crucial. In many cases, the cause of Cerebral palsy may not be apparent. Cerebral palsy is invariably associated with many deficits such as mental retardation, speech and language and oromotor problems. A thorough neurodevelopmental assessment of the child with Cerebral Palsy should include evaluation of associated deficits so that a comprehensive early intervention program an be planned and executed.

Age Factors↗

Correlation between prenatal velocity waveforms in the aortic isthmus and neurodevelopmental outcome between the ages of 2 and 4 years.

OBJECTIVE: Experimental studies on fetal lambs have shown that during an increase in the resistance to placental flow the delivery of oxygen to the brain is preserved as long as net flow through the aortic isthmus is antegrade. Our purpose was to determine whether the same changes in aortic isthmus flow in human subjects have any impact on neurodevelopmental outcome. STUDY DESIGN: Forty-four fetuses were retrospectively included in this study on the basis of an abnormal Doppler velocity in the umbilical artery. Mean gestational age at delivery was 33.0 +/- 2.0 weeks and mean birth weight 1386 +/- 435 g. The neurodevelopmental condition was assessed between the ages of 2 and 4 years. The developmental score was analyzed in relation to the flow patterns in the fetal aortic isthmus, which were classified as follows: group A, net isthmic flow antegrade (defined as the ratio of the systolic antegrade to the diastolic retrograde velocity integrals) (n = 39); group B, net isthmic flow retrograde (n = 5). RESULTS: Nonoptimal neurodevelopment was observed in 19 (49%) of 39 fetuses in group A and in all 5 fetuses (100%) in group B. This difference is significant and leads to a relative risk of 2.05 (95% confidence interval, 1.49-2.83) for neurodevelopmental deficit when predominantly retrograde flow is observed in the fetal aortic isthmus before birth. CONCLUSION: Measuring the ratio of antegrade to retrograde velocity integrals in the aortic isthmus could help in the indirect assessment of cerebral oxygenation during placental circulatory insufficiency.

Aorta↗

Stratifying the risk of transition to adult-onset psychiatric disorders in adolescents with anxiety.

BACKGROUND: Escalating mental health service demands have created a need to better identify young people most likely to require continued support from mental health services at the transition between childhood and adulthood. Anxiety is the most common adolescent mental health condition, yet its clinical significance and prognosis are not well understood. We aimed to examine the risk of young adult-onset psychiatric disorders in individuals with an adolescent anxiety disorder, and identify stratifiers of risk of subsequent psychiatric disorders in this group. METHODS: Individuals from the Norwegian Mother, Father, and Child Cohort Study (MoBa) with linked health records and aged 18 or over as of the 31st December 2023 were included. Those diagnosed with any ICD-10 anxiety disorder when aged 10-17 years were defined as having an adolescent anxiety disorder (n=2107, controls n=47,582). Polygenic scores (PGS) for psychiatric and neurodevelopmental conditions were calculated using LDpred2. Anxiety, comorbidities, and parental psychiatric history were defined through linked ICD-10 diagnoses. Sex was defined through linked records. Individuals were defined as having a young adult-onset psychiatric disorder if they first received any new psychiatric diagnosis aged 18-24. RESULTS: Adolescent anxiety diagnosis was associated with increased risk of all adult-onset psychiatric disorders (HR= 2.33-8.65). Post-traumatic stress disorder PGS, parental history of severe mental illness, and female sex were associated with increased risk of transition to a young adult-onset psychiatric disorder in people with an adolescent anxiety disorder. CONCLUSIONS: Adolescent anxiety greatly increases the risk of a psychiatric disorder during the transition to adult life. Clinicians should consider female sex and parental psychiatric history when prioritising young people with anxiety for adult mental health service support. Future research needs to further consider whether polygenic scores would aid risk stratification in clinical practice.

Norwegian Mother Father and Child Cohort Study↗

Untargeted metabolomics and proteomics reveals cocoa-mediated mitigation of valproic acid-induced dysregulation in a zebrafish model of autism: pilot study.

INTRODUCTION: Autism spectrum disorder (ASD) is a neurodevelopmental condition characterized by behavioral impairments and limited therapeutic options. Emerging evidence suggests that plant-derived polyphenols may offer neuroprotective benefits. OBJECTIVES: This pilot study aimed to investigate the therapeutic potential of polyphenol-rich cocoa extract in a valproic acid (VPA)-induced zebrafish model of ASD. METHODS: Zebrafish were exposed to 3 μM VPA, cocoa powder providing 2.5 μM (-)-epicatechin, a combination of both, or left untreated. Behavioral phenotyping was conducted using DanioVision and gut morphology was assessed. Untargeted metabolomic and proteomic profiling was performed followed by univariate and multivariate analyses. RESULTS: VPA exposure induced ASD-like behavioral hyperactivity, and severe gastrointestinal abnormalities. Cocoa co-treatment ameliorated both behavioral performance and gut architecture. Metabolomic profiling revealed VPA-associated disruptions in neurotransmission, methylation, mitochondrial function and redox homeostasis. Proteomic profiling showed elevated levels of trafficking protein particle complex subunit 11, proteasomal ubiquitin receptor, betaine-homocysteine S-methyltransferase 1 (BHMT-1), and desmoplakin-A, consistent with genotoxic stress and impaired protein trafficking. Cocoa co-treatment normalized BHMT-1 and desmoplakin-A expression and mitigated broader metabolic dysregulation. CONCLUSION: Collectively, these results suggest that polyphenol-rich cocoa may represent a promising multi-targeted nutraceutical approach for mitigating ASD-related neurodevelopmental and metabolic disturbances.

Animals↗

Shared genetic architecture between ADHD and intelligence varies across ADHD subtypes.

BACKGROUND: Attention-deficit/hyperactivity disorder (ADHD) is a heterogeneous neurodevelopmental condition frequently accompanied by cognitive difficulties. Although previous genetic studies have demonstrated substantial overlap between ADHD and intelligence, most have treated ADHD as a single phenotype. However, whether this shared genetic architecture differs across ADHD subtypes remains unclear. METHODS: We conducted a genome-wide cross-trait analysis integrating large-scale genome-wide association study (GWAS) datasets of overall ADHD, its subtypes-childhood ADHD, persistent ADHD, and late-diagnosed ADHD-and intelligence (total N > 300,000). Genome-wide genetic correlations, polygenic overlap, local genetic correlations, and variant-level associations between ADHD phenotypes and intelligence were evaluated to characterize their shared genetic architecture. Shared variants were identified through cross-trait enrichment analyses and subsequently mapped to genes for functional annotation and gene-set enrichment. Bidirectional associations were evaluated using two-sample Mendelian randomization with sensitivity analyses. Additional GWAS datasets were used to validate the robustness of shared loci by assessing the consistency of effect directions. RESULTS: All ADHD phenotypes showed significant negative genetic correlations with intelligence (rg ranging from -0.3442 to -0.4205). Despite these modest genome-wide correlations, cross-trait analyses revealed substantial genetic overlap, including polygenic overlap, local genetic correlations, and variant-level associations. We identified 184 loci jointly associated with ADHD traits and intelligence, including 64 novel loci, whereas no shared loci were detected for persistent ADHD under the current analysis. Functional annotation revealed biologically distinct enrichment patterns across subtypes: childhood ADHD loci were linked to early neurodevelopmental processes, while late-diagnosed ADHD loci were enriched in synapse-related and neuronal signaling pathways. Mendelian randomization analyses suggested bidirectional associations, with stronger evidence supporting a directional association from intelligence to ADHD risk. Furthermore, these shared loci showed largely consistent effect directions across additional GWAS datasets, providing support for the robustness of the findings. CONCLUSIONS: The shared genetic architecture between ADHD and intelligence varies across ADHD subtypes, highlighting distinct biological pathways underlying cognitive heterogeneity in ADHD. These findings suggest that the relationship between ADHD liability and general cognitive ability is not uniform across ADHD subtypes and may inform future research on risk stratification and early identification in child and adolescent psychiatry.

Humans↗

Polygenic risk score for neurodevelopmental disorders and cognitive impairment at long-term follow-up of first-episode psychosis.

BACKGROUND: One of the most outstanding contributions to the understanding of the etiopathogenesis of schizophrenia spectrum disorders (SSD) was the neurodevelopmental hypothesis. SSD and neurodevelopmental disorders (NDD) share pathogenetic mechanisms and overlapping clinical and cognitive impairment features. METHODS: We investigated whether polygenic risk scores (PRSs) for NDD are associated with cognitive performance in patients with first-episode psychosis (FEP). The sample comprised 127 patients with FEP who were followed up for a mean of 20.9 years. Cognitive examination was performed using the MoCA test at follow-up. Pearson coefficient correlations and multiple regression analyses were performed to examine the contribution of the three PRSs for rare neurodevelopmental conditions (PRSNDD), attention-deficit hyperactivity disorder (PRSADHD) and autism spectrum disorder (PRSASD) to cognitive impairment after allowing for the effect of covariates. Furthermore, we examined the interconnections between the PRS for NDD and cognitive impairment using network analysis (NA), including core premorbid variables. RESULTS: PRSNDD showed significant associations with impairment on visuospatial/executive, attention, and language MoCA subtests, after allowing for the influence of covariates. PRSNDD and PRSADHD, but not PRSASD, were significantly associated with worse performance on the total MoCA score. Moreover, in the network analysis, the relationships between PRSs for NDD and cognitive impairment were highly interconnected with premorbid variables and PRSs for schizophrenia and educational attainment. CONCLUSIONS: These results provide evidence for a possible direct genetic effect on cognitive performance for the PRS of common genetic variations related to neurodevelopment and attention deficit hyperactivity disorder in patients with FEP.

Cognitive impairment↗

Deciphering the Role of LNX2 as a Potential Contributor to Neurodevelopmental Disorders.

BACKGROUND/OBJECTIVES: Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental condition characterized by a complex and multifactorial genetic architecture. In this study, we report a male patient, born to non-consanguineous healthy parents, presenting with ADHD and oppositional defiant disorder (ODD). METHODS: Trio-based whole-exome sequencing (WES) was performed in the proband and both parents. Variant classification was performed according to American College of Medical Genetics and Genomics (ACMG) guidelines, and the potential pathogenicity of the identified variant was further assessed through multiple in silico prediction algorithms and protein structural analyses. RESULTS: WES identified a homozygous variant in the LNX2 gene (NM_153371.4: c.1165G>A, p.Ala389Thr), classified as a variant of uncertain significance (VUS) and supported by multiple in silico predictions. LNX2 is expressed during brain development and encodes an E3 ubiquitin ligase involved in neuronal differentiation and synaptic function. The identified variant is located within the PDZ2 domain, a functionally relevant region involved in protein-protein interactions. Although the variant is reported in population databases (gnomAD ID: rs148429804), it has not been associated with any clinical phenotype, and its presence in the homozygous state has been reported only once, remaining extremely rare and lacking clinical annotation. Structural modelling predicted localized rearrangement of the hydrogen-bonding network within the PDZ2 domain without major conformational changes. Integrative transcriptomic, and single-cell analyses further supported the biological relevance of LNX2 in neurodevelopment, highlighting its preferential association with neuronal projection-cell networks, synaptic vesicle trafficking pathways, and neuron-specific regulatory programs. CONCLUSION: Although the identified LNX2 variant cannot be considered causative for the patient's phenotype and a definitive disease-gene relationship cannot be established based on a single individual, the complementary genetic, structural, and transcriptomic findings support the biological plausibility of LNX2 as a candidate gene for neurodevelopmental disorders. Additional independent patients and functional studies will be required to clarify its contribution to human disease.

Child↗

[Tics and Tourette Syndrome].

Tics disorders and Tourette syndrome (TS) are neurodevelopmental conditions characterized by motor and/or vocal tics with onset in childhood. Their clinical presentation is heterogeneous and fluctuating over time, with exacerbations related to emotional, environmental, and medical factors. Diagnosis is clinical and based on medical history and neurological examination, following DSM-5-TR criteria, with ancillary testing rarely required. The prevalence of TS is estimated at 0.7%, while transient tic disorders affect up to 10% of children. The natural history is generally favorable, with symptom improvement during adolescence, although a subset of patients continues to experience tics into adulthood. Most individuals with TS present psychiatric comorbidities, particularly attention-deficit/hyperactivity disorder and obsessive-compulsive disorder, which significantly impact quality of life and should be prioritized in management decisions. Treatment is recommended only when tics cause functional impairment and follows a stepwise approach including psychoeducation, behavioral interventions, and individualized pharmacological therapy. Comprehensive behavioral intervention for tics is considered first-line treatment when available. Alpha-2 adrenergic agonists and dopamine antagonists are the most commonly used pharmacological options. Neuromodulation therapies are reserved for severe, refractory cases. These recommendations from the Ibero-American Academy of Pediatric Neurology summarize current evidence and provide a practical, updated framework for the diagnosis and management of tic disorders and Tourette syndrome in pediatric patients.

Humans↗

Neurocorrelates of nocturnal enuresis in pre-adolescent children.

INTRODUCTION: Nocturnal enuresis (NE) is a common neurodevelopmental condition, yet its underlying neural mechanisms remain unclear. This study leverages the large-scale Adolescent Brain Cognitive Development (ABCD) dataset to identify structural and functional brain correlates associated with active symptoms and the resolution of bedwetting. METHODS: Using cross-sectional data from 3472 participants aged 9-10 years, children were categorized into three groups: active nocturnal enuresis (ANE, n = 225), history of nocturnal enuresis (HNE, n = 1171), and healthy control groups (CG, n = 2076). Multimodal neuroimaging protocol evaluated macrostructural properties via structural MRI (sMRI), microstructural white matter integrity via diffusion MRI (dMRI), and functional connectivity via resting-state fMRI (fMRI). Group differences were evaluated using linear models within an ANCOVA framework, adjusting for intracranial volume and handedness with False Discovery Rate (FDR) correction. RESULTS: Compared to controls, the ANE group exhibited a significant volume deficit in the right caudate, decreased sulcal depth in the left insula, and lower internal correlation within the Cingulo-Opercular Network (CON). Conversely, the dry HNE group demonstrated significant structural adaptations, including bilaterally larger putamen volumes and increased right caudate volume compared to the ANE group. The HNE group also showed increased microstructural density (decreased mean diffusivity) in the bilateral hippocampus and an increased cortical surface area in the left insula. Both NE groups demonstrated persistently reduced functional coupling within the CON. CONCLUSIONS: Nocturnal enuresis appears to be associated with a potential complex central signaling deficits. Reduced internal correlation within the CON across both active and former bedwetters indicates a potential for impairment in processing internal homeostatic bladder signals during sleep.

Humans↗

Clinical Utility of Trio Exome Sequencing in Rwandan Children With Autism Spectrum Disorder.

INTRODUCTION: Autism spectrum disorder (ASD) is a neurodevelopmental condition with substantial genetic and phenotypic heterogeneity. However, populations of African ancestry remain underrepresented in genomic studies, limiting understanding of ASD genetic architecture. This study aimed to characterize rare, clinically relevant genetic variants in a Rwandan pediatric ASD cohort using trio-based whole-exome sequencing (WES). METHODS: Trio-based WES was performed in 31 Rwandan pediatric patients with ASD (aged 2-18 years) and their parents. Variants were analyzed using a trio-based workflow and classified according to American College of Medical Genetics and Genomics/Association for Molecular Pathology (ACMG/AMP) guidelines. RESULTS: Eleven candidate variants were identified in 9 of 31 patients, including four likely pathogenic variants and seven variants of uncertain significance. This resulted in a diagnostic yield of 12.9% (4/31), expanded to 29.0% when phenotypically concordant variants of uncertain significance were considered. Most likely pathogenic variants were identified in individuals with syndromic ASD who presented with intellectual disability, epilepsy, and global developmental delay. Likely pathogenic findings included two single nucleotide variants in GABRB3, SYNGAP1, and two copy-number variants involving the GNAS locus and chromosome 1p35.3-p35.2. CONCLUSIONS: The diagnostic yield observed in this cohort is consistent with previous trio-based WES studies of ASD. The findings support the clinical utility of WES for the genetic evaluation of ASD and underscore the need for expanded genomic studies in African populations.

Humans↗

Small RNAs in human brain development and disorders.

Small RNA is a variable and abundant type of non-coding RNAs in brain. The function of these RNAs is mainly unknown. A specific class of small RNA, microRNA, is dynamically regulated in neurogenesis and in embryo brain development. The genes for synaptic formation and some mental retardation disorders are putative targets for microRNA predicted by computational algorithms. The molecular pathways for mental development, common forms of autisms, schizophrenia, and affective disorders have yet to be elucidated. The hypothesis proposed here is that small regulatory RNAs, specifically microRNAs, play a role in human brain development and pathogenesis of brain disorders, especially of neurodevelopmental conditions. Pilot tests using comprehensive arrays of microRNAs demonstrate that microRNAs derived from postmortem human brains are applicable for microRNA expression profiling. The abundant expression of many regulatory small RNAs in human brain implies their biological role that must be tested by functional assays in neurons and by genetic and comparative expression profiling.

Brain↗