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An evaluation of the effects of thimerosal on neurodevelopmental disorders reported following DTP and Hib vaccines in comparison to DTPH vaccine in the United States.

Thimerosal is an ethylmercury (49.55% mercury by weight) preservative historically added to some vaccines. Toxicokinetic studies showed children in the United States received doses of mercury from Thimerosal-containing vaccines (TCVs) in excess of safety guidelines. In the United States during the 1990s, diphtheria-tetanus-pertussis (DTP) and Haemophilus influenzae type b (Hib) vaccines (maximally, 50 mug mercury per joint administration) and diphtheria-tetanus-pertussis-Haemophilus influenzae type b (DTPH) vaccines (25 mug mercury per administration) were given to children in the same childhood vaccination schedule at 2, 4, 6, and 15-18 mo, so that children receiving DTP and Hib vaccines may have maximally received an additional 100 mug more mercury exposure from TCVs than children administered DTPH vaccines. A case-control epidemiological study of neurodevelopmental disorders (NDs) reported to the Vaccine Adverse Event Reporting System (VAERS) (online public access version; updated 31 August 2004) following administration of DTP vaccines in comparison DTPH vaccines manufactured by Lederle Laboratories (Pearl River, NY) from 1994 through 1998 was undertaken. Significantly increased odds ratios for autism, speech disorders, mental retardation, infantile spasms, and thinking abnormalities reported to VAERS were found following DTP vaccines in comparison to DTPH vaccines with minimal bias or systematic error. Additional ND research should be undertaken in the context of evaluating mercury-associated exposures, especially since in 2005 the Institute of Medicine issued a report calling into question handling of vaccine safety data by the National Immunization Program of the Centers for Disease Control and Prevention.

Bacterial Capsules↗

Social neuroscience, empathy, brain integration, and neurodevelopmental disorders.

Paul MacLean has investigated integrated brain functioning through selected brain lesions in animals that disturb circuits necessary for complex behaviors, such as social displays. MacLean is unique in his comparative neurobehavioral approach that emphasizes the evolutionary origins of parenting and social behaviors and the implications of brain changes in the evolution from reptiles (social displays) to mammals (nursing, audiovocal communication, play) to man (self-awareness, intentionality, social context) that link affect and cognition. Subjectively, how "looking with feeling toward others," the basic element in empathy, evolved has been a central concern of his. Neuroimaging studies of social cognition, mother-infant communication, moral behavior, forgiveness, and trust are consistent with particular brain systems being activated in cooperative social behaviors. The identification of mirror neurons is pertinent to MacLean's model of isopraxis and studies of thalamocortical resonances may be pertinent to his neurobehavioral models. Studies of behavioral phenotypes in human neurodevelopmental disorders are consistent with MacLean's model of brain circuits being linked to complex behaviors during development. In autistic disorder, the behavioral phenotype involves disrupted social communication, deviant imaginative play, and motor stereotypies. In Lesch-Nyhan syndrome (LNS), self-injury occurs in individuals with normal sensory systems intact who require and request physical restraint to prevent self-injury; they ask for assistance from others to prevent them from harming themselves. Autism involves the lack of subjective awareness of others intentions and LNS involves a failure in self-regulation and self-control of self-injurious behavior. MacLean's models laid the groundwork for studies focused on understanding brain functioning in these conditions.

Animals↗

Interruptions of early cortical development affect limbic association areas and social behaviour in rats; possible relevance for neurodevelopmental disorders.

Deficits in social behaviour are found in several neuropsychiatric disorders with a presumed developmental origin. Adequate social behaviour may rely importantly on the associative integration of new stimuli with previously stored, related information. The limbic allocortex, in particular the entorhinal region, is thought to support this kind of processing. Therefore, in the present study, gestating dams were treated with methylazoxymethanol acetate (MAM) on one of gestational days nine to twelve, to interrupt neuronal proliferation in the entorhinal region of the developing foetuses. Effects of prenatal MAM administration on social behaviour were evaluated in adult animals. As the entorhinal cortex has been implicated by some studies in spatial memory, effects on this function were also investigated. Following the behavioural studies, brain morphology was screened for effects of MAM. Our results show moderate to severe social impairment in MAM-treated animals, depending on the exact timing of prenatal exposure. By contrast, spatial reference and working memory were not importantly affected in any group. Analysis of brain morphology in the MAM-treated offspring supported maldevelopment of the entorhinal cortex and revealed mild abnormalities also in some connected limbic and limbic affiliated structures, such as the perirhinal and ectorhinal cortex, the anterior cingulate cortex and the medial septum-diagonal band region. Findings are discussed with respect to entorhinal cortex function, and with regard to their relevance for psychiatric disorders with a putatively neurodevelopmental pathogenesis, such as schizophrenia.

Animals↗

Maternal neuronal antibodies associated with autism and a language disorder.

Neurodevelopmental disorders could be caused by maternal antibodies or other serum factors. We detected serum antibodies binding to rodent Purkinje cells and other neurons in a mother of three children: the first normal, the second with autism, and the third with a severe specific language disorder. We injected the serum (0.5-1.0 ml/day) into pregnant mice during gestation and found altered exploration and motor coordination and changes in cerebellar magnetic resonance spectroscopy in the mouse offspring, comparing with offspring of mice injected with sera from mothers of healthy children. This evidence supports a role for maternal antibodies in some forms of neurodevelopmental disorder.

Adult↗

A novel DPH5-related diphthamide-deficiency syndrome causing embryonic lethality or profound neurodevelopmental disorder.

PURPOSE: Diphthamide is a post-translationally modified histidine essential for messenger RNA translation and ribosomal protein synthesis. We present evidence for DPH5 as a novel cause of embryonic lethality and profound neurodevelopmental delays (NDDs). METHODS: Molecular testing was performed using exome or genome sequencing. A targeted Dph5 knockin mouse (C57BL/6Ncrl-Dph5em1Mbp/Mmucd) was created for a DPH5 p.His260Arg homozygous variant identified in 1 family. Adenosine diphosphate-ribosylation assays in DPH5-knockout human and yeast cells and in silico modeling were performed for the identified DPH5 potential pathogenic variants. RESULTS: DPH5 variants p.His260Arg (homozygous), p.Asn110Ser and p.Arg207Ter (heterozygous), and p.Asn174LysfsTer10 (homozygous) were identified in 3 unrelated families with distinct overlapping craniofacial features, profound NDDs, multisystem abnormalities, and miscarriages. Dph5 p.His260Arg homozygous knockin was embryonically lethal with only 1 subviable mouse exhibiting impaired growth, craniofacial dysmorphology, and multisystem dysfunction recapitulating the human phenotype. Adenosine diphosphate-ribosylation assays showed absent to decreased function in DPH5-knockout human and yeast cells. In silico modeling of the variants showed altered DPH5 structure and disruption of its interaction with eEF2. CONCLUSION: We provide strong clinical, biochemical, and functional evidence for DPH5 as a novel cause of embryonic lethality or profound NDDs with multisystem involvement and expand diphthamide-deficiency syndromes and ribosomopathies.

Adenosine Diphosphate↗

Pathogenic Variants in MPDZ are Associated with a Syndromic Neurodevelopmental Disorder: A Case Report and Review of the Literature.

Pathogenic variants in MPDZ are typically associated with congenital hydrocephalus. We report on siblings who present with more complex central nervous system malformations and defects in cardiovascular, ocular, and respiratory systems. Phenotyping of the proband revealed aortic coarctation, bicuspid aortic valve, partial anomalous pulmonary venous return, ventricular septal defect, Dandy-Walker malformation, along with subependymal gray matter heterotopia, megalocornea, and chorioretinal punctate lesions. Prenatal phenotyping of the proband's now deceased brother noted left-sided diaphragmatic hernia, a single cardiac ventricle of right ventricular morphology, aortic and mitral valve hypoplasia with aortic coarctation, ventriculomegaly, and mega cisterna magna. Whole genome sequencing identified a homozygous likely pathogenic canonical splice site variant in MPDZ, c.2650-1G>A in both siblings. These siblings present with features suggesting that MPDZ pathogenicity may be associated with a more complex syndromic neurodevelopmental phenotype with both central nervous system and non-central nervous system features. We speculate that MPDZ influences common morphogenetic pathways underlying these relationships.

Humans↗

[Genetic and phenotypic analysis of three children with Neurodevelopmental disorders due to variants of DEAF1 gene].

OBJECTIVE: To explore the genetic characteristics and clinical phenotypes of three children with novel DEAF1 gene variants. METHODS: Three children who were referred to Capital Children's Medical Center Affiliated to Capital Medical University between January 2018 and December 2025 were selected as study subjects and underwent whole exome sequencing (WES). Candidate variants were verified by Sanger sequencing, and their pathogenicity was evaluated based on the guidelines from American College of Medical Genetics and Genomics (ACMG). A systematic search of databases including PubMed and CNKI was conducted to compile previously reported cases of DEAF1 variants for clinical phenotype comparison. For the non-canonical splice site variant c.870+5G>C located in the intronic region, wild-type and mutant minigene reporter vectors were constructed and transfected into HeLa and 293T cells, respectively, and the splicing patterns were analyzed by RT-PCR and Sanger sequencing. This study was approved by the Medical Ethics Committee of Capital Institute of Pediatrics (Ethics No.: SHERLL 2020001). RESULTS: All three children were found to have carried de novo heterozygous variants of the DEAF1 gene, including two missense variants (c.764G>A, c.641T>C) in the important SAND domain and a splice site variant (c.870+5G>C) in a non-canonical splicing region. The c.764G>A and c.870+5G>C variants were unreported previously. All children had presented with intellectual developmental delay, and two were accompanied by autism spectrum disorder, and two had epilepsy and sleep disorders. In vitro minigene splicing assay showed that the c.870+5G>C variant can lead to abnormal splicing. CONCLUSIONS: This study reported three children with novel DEAF1 variants, two of which have not been previously described, thereby enriched the mutational spectrum of the DEAF1 gene. In vitro functional assay combined with the clinical manifestations of the patients confirmed the pathogenicity of the non-canonical splice site variant in the intronic region.

Humans↗

Upregulation versus loss of function of NTRK2 in 44 affected individuals leads to 2 distinct neurodevelopmental disorders.

PURPOSE: Heterozygous pathogenic variants in NTRK2 (HGNC: 8032) have been associated with global developmental delay. However, only scattered cases have been described in small or general studies. The aim of our work was to consolidate our understanding of NTRK2-related disorders and to delineate the clinical presentation. METHODS: We reported an extended cohort of 44 affected individuals, of whom 19 are from the literature and 25 were previously unreported. RESULTS: Our analysis led to splitting the cohort into 2 entities. CONCLUSION: One group had variants in the cholesterol-binding motif of the transmembrane domain, with most of these being the recurrent variant c.1301A>G p.(Tyr434Cys). These variants probably lead to upregulation of tropomyosin receptor kinase B activity and to a severe phenotype of developmental delay/intellectual disability, muscular hypotonia, therapy-refractory epilepsy, visual impairment and blindness, and feeding difficulties. The second group had truncating variants or variants that presumably disturb the 3D structure of the protein leading to loss of function. These individuals had a remarkably milder phenotype of developmental delay, obesity, and hyperphagia.

Humans↗

Primary neonatal hyperparathyroidism: a devastating neurodevelopmental disorder if left untreated.

We describe a 29-year-old male with untreated primary neonatal hyperparathyroidism. Hypotonia, poor feeding, failure to thrive, and developmental delay were noted in early infancy and in incidental serum calcium of 3.8 mmol/L was dismissed as a laboratory error. Childhood was characterized by profound muscle wasting and progressive spastic quadriparesis. Distinctive skeletal deformities, facial dysmorphism, and perichondral calcifications are now evident in adulthood. Elevated serum calcium (range: 2.7-3.3 mM; normal less than 2.7 mM), serum immunoreactive parathyroid hormone (range: 1,405-1,817 pg/mL; normal 50-140 pg/mL), and markedly decreased urinary calcium excretion (0.04 mumol/dL glomerular filtrate; normal greater than 25) suggested the diagnosis of primary neonatal hyperparathyroidism. This was supported by evidence of hypocalciuric hypercalcemia--the autosomal dominant carrier state--in both the parents. Our case illustrates the profound neurodevelopmental deficits arising from sustained hypercalcemia in infancy and childhood. Although this disorder is not lethal, it should be considered a neonatal emergency, since surgical parathyroidectomy can result in cure.

Adult↗

Brain N-acetyl aspartate concentrations measured by H MRS are reduced in adult male rats subjected to perinatal stress: preliminary observations and hypothetical implications for neurodevelopmental disorders.

The present study was undertaken to determine if the concentration of brain N-acetyl-aspartate (NAA), a putative neuronal marker, is reduced in adult rats subjected to stress during the perinatal period. As the prenatal stressor, pregnant rats were subjected to restraint stress for one hour twice daily from days 14-21 of gestation; stressed offspring were reared by normal dams and studied as adults. As the postnatal stressor, normal pups were reared by prenatally 'stressed' dams and studied as adults. As compared to non-stressed controls (n=6), NAA concentrations were significantly reduced 21 and 25% in left frontal cortex from the prenatal (n=4) and postnatal (n=6) stress groups. respectively. The data suggest that in perinatally stressed adult offspring permanent neuronal damage or loss has occurred. While no direct causal associations between perinatal stress and the developmental of particular disorders can be inferred from these limited data, the effects of perinatal stress on subsequent brain neuropathology are reviewed. particularly in relation to NAA. For hypothesis-generating purposes, the possible relevance of stress and NAA to the neurodevelopmental hypothesis of schizophrenia is discussed in greater detail.

Age Factors↗

Gene Specific Pathogenicity Predictor for Chromatin-Remodeling BAF Complex-Associated Neurodevelopmental Disorders.

Advancements in whole genome sequencing have increased the number of variants of uncertain significance (VUS) identified in patient genomes. This has created a diagnostic bottleneck for genetic counselors tasked with sifting through these variants and determining those most likely to be causative for a patient's clinical presentation. Machine learning (ML) tools can aid in identifying pathogenic variants from VUS, but there is a need for gene-specific algorithms that predict pathogenic variants with high accuracy. To address this need, we present a workflow for developing gene-specific, ensemble-learning ML tools, that leverage outputs from other algorithms, locations of variants within the gene, and evolutionary conservation data to make a prediction of pathogenicity. Variants in SMARCA2 and SMARCA4 that are associated with rare neurodevelopmental diseases were used to screen 15 ML algorithms. A random forest learner was tuned to yield a final accuracy of 0.93 on holdout data. Generalizing this predictor to other BAF complex proteins resulted in a sharp decline in performance. We trained a final predictor for all genes in the study to create a predictor that identifies pathogenic variants in these BAF subunits with an accuracy of 0.91 on holdout data. This predictor specific to BAF complex proteins performs with higher accuracy and AUROC than any other predictor. The decline in performance when generalized to other proteins emphasizes the need for the gene-specific calibration of predictors. Our workflow for the development of such models provides a quick, computationally inexpensive route for improving the ML tools available to genetic counselors.

Journal Article↗

Serotonin depletion during synaptogenesis leads to decreased synaptic density and learning deficits in the adult rat: a possible model of neurodevelopmental disorders with cognitive deficits.

Studies in the past have revealed serotonin to play a role in regulating the development and maturation of the mammalian brain, largely through the release of the astroglial protein S-100beta. S-100beta plays a role in neurite extension, microtubule and dendritic stabilization and regulation of the growth associated protein GAP-43, all of which are key elements in the production of synapses. Depletion of serotonin, and thus of S-100beta, during synaptogenesis should lead to a loss of synapses and the behaviors dependent on those synapses. The current study was undertaken to test this hypothesis. In order to assess the influence of serotonin we have looked at the synaptic density in the adult after depletion, by using immunodensitometry of synaptic markers (synaptophysin and MAP-2) and by studying behaviors thought to be highly dependent on synaptic plasticity and density. Male Sprague-Dawley rats were depleted of serotonin on postnatal days (PND) 10-20 by treating with the tryptophan hydroxylase inhibitor parachlorophenylalanine (PCPA; 100 mg/kg, s.c.). On PND's 30 and 62, animals were perfused for immunodensitometry. Littermates were used for behavioral testing. At PND 55-62, the animals were tested in an interchangeable maze with olfactory cues and in an eight-arm radial maze. Our results show a loss of both synaptic markers in the hippocampus on PND 30. At PND 62, the only remaining loss was of the dendritic marker MAP-2. The animals had deficits in both behaviors tested, suggestive of spacial learning deficits and of the failure to extinguish learned behaviors or to re-learn in a new set. Our findings show the long-term consequences of interfering with the role of serotonin in brain development on the morphology and function of the adult brain. These findings may have implications for human diseases, including schizophrenia, thought to be related to neurodevelopmental insults such as malnutrition, hypoxia, viruses or in utero drug exposure. Moreover, they provide further insights into the functioning of serotonin and S-100beta in development and aging.

Animals↗

An animal model of chronic placental insufficiency: relevance to neurodevelopmental disorders including schizophrenia.

Evidence now suggests that compromised prenatal brain development may increase the risk for the manifestation of neurological disorders such as schizophrenia. We present a guinea-pig model which mimics a condition of human pregnancy, namely, chronic placental insufficiency. Previously we reported that at term there are changes in the brains of these offspring which are relevant to changes in patients with schizophrenia. The aim of this study was to examine whether deficits in brain structure persist to adolescence and young adulthood (8-12 weeks) and have implications for behavioral function. Reduced uteroplacental blood flow was induced via unilateral ligation of the uterine artery at mid-gestation. The brain was examined in control and prenatally compromised (PC) animals 8 weeks after birth using morphometric and immunohistochemical markers. In a separate cohort of animals, prepulse inhibition (PPI) of the acoustic startle response was assessed at 4, 8 and 12 weeks of age. Brain neurochemistry was examined by determining the concentrations of dopamine and its metabolite, dihydroxyphenylacetic acid (DOPAC), at 12 weeks using high performance liquid chromatography. In PC animals compared with controls there was a reduction in brain weight, persistent enlargement of the lateral ventricles, a reduction in the volume of the basal ganglia and septal region and no evidence of gliosis. No differences were observed in concentration of catecholamines in any brain region examined. At 12, but not 4 or 8, weeks of age, PPI was reduced in PC animals compared with controls. The findings of reduced brain weight, ventriculomegaly, reduced basal ganglia volume and absence of astrogliosis in the PC guinea-pig brain at adolescence parallel some of the changes observed in patients with schizophrenia. The impairment of PPI is comparable to sensorimotor gating deficits observed in patients with schizophrenia. These results indicate that adverse prenatal conditions lead to long-term alterations in brain structure and function which resemble alterations seen in patients with schizophrenia and therefore support the early neurodevelopmental hypothesis of schizophrenia.

Animals↗

Callosal morphology concurs with neurobehavioral and neuropathological findings in two neurodevelopmental disorders.

To integrate neuroimaging, neuropathologic, and neuropsychological findings, computer-assisted morphometry was applied to magnetic resonance images of the corpus callosum in adolescents with Down and Williams syndromes and in control subjects. Callosa of subjects with Down syndrome were distinctively rounded in form, consistent with Down syndrome brachycephaly. These callosa also showed decreased widths throughout their rostral fifth, which serves frontal lobe projections. This finding correlates with the hypocellularity and hypofrontality of neocortex in subjects with Down syndrome and with their neuropsychological profile of frontal lobe dysfunction. Callosa of subjects with Williams syndrome generally resembled control specimens, in congruence with their frontal lobe structure and better preserved frontal lobe function. These results represent a convergence of findings across levels of neuroscientific investigation.

Adolescent↗