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1q21.1 distal copy number variants are associated with cerebral and cognitive alterations in humans.

Low-frequency 1q21.1 distal deletion and duplication copy number variant (CNV) carriers are predisposed to multiple neurodevelopmental disorders, including schizophrenia, autism and intellectual disability. Human carriers display a high prevalence of micro- and macrocephaly in deletion and duplication carriers, respectively. The underlying brain structural diversity remains largely unknown. We systematically called CNVs in 38 cohorts from the large-scale ENIGMA-CNV collaboration and the UK Biobank and identified 28 1q21.1 distal deletion and 22 duplication carriers and 37,088 non-carriers (48% male) derived from 15 distinct magnetic resonance imaging scanner sites. With standardized methods, we compared subcortical and cortical brain measures (all) and cognitive performance (UK Biobank only) between carrier groups also testing for mediation of brain structure on cognition. We identified positive dosage effects of copy number on intracranial volume (ICV) and total cortical surface area, with the largest effects in frontal and cingulate cortices, and negative dosage effects on caudate and hippocampal volumes. The carriers displayed distinct cognitive deficit profiles in cognitive tasks from the UK Biobank with intermediate decreases in duplication carriers and somewhat larger in deletion carriers-the latter potentially mediated by ICV or cortical surface area. These results shed light on pathobiological mechanisms of neurodevelopmental disorders, by demonstrating gene dose effect on specific brain structures and effect on cognitive function.

Brain↗

Postnatal development of the primate hippocampal formation.

The hippocampal formation is a multicomponent region of the medial temporal lobe preferentially involved in declarative and relational memory processing. Behavioral studies have suggested a protracted functional maturation of these structures in primates, and postnatal developmental abnormalities in the hippocampal formation are thought to contribute to neurodevelopmental disorders, such as autism, schizophrenia, epilepsy and Down syndrome. Despite all that we know about the functional organization of the adult hippocampal formation, notably absent is a systematic study of its postnatal maturation in primates. In this article, we review current knowledge of the structural development of the primate hippocampal formation and present new data on its postnatal neuroanatomical development. We summarize what is known about the neurobiological processes, such as the addition of new neurons, the establishment and elaboration of connectivity, and the neurochemical changes, that underlie the structural development and functional maturation of the primate hippocampal formation. We conclude that there is yet insufficient information to identify distinct developmental windows during which different hippocampal regions undergo specific maturational processes. For this reason, it is currently impossible to determine the ages at which specific hippocampal circuits become structurally mature and potentially capable of supporting defined, age-specific functional processes. Together with work in rodents, systematic studies of the structural development and functional maturation of the monkey hippocampal formation will be necessary to gain insight not only into the types of information processing that it subserves, but also into the specific maturational processes that might be affected in human neurodevelopmental disorders.

Aging↗

Disruption of GAD1 protein architecture by a novel missense variant in a consanguineous family with autosomal recessive intellectual disability.

BACKGROUND: Intellectual disability represents a heterogeneous group of neurodevelopmental disorders marked by significant impairments in intellectual functioning and adaptive behavior. Among the various causes, genetic factors play a major role, with autosomal recessive intellectual disability (ARID) constituting a genetically diverse subgroup. ARID is prevalent in consanguineous families and arises from homozygous mutations that disrupt critical genes involved in brain development and function. OBJECTIVE: This study aimed to identify disease-causing genetic variants responsible for ARID in a consanguineous Pakistani family and to evaluate the structural and functional impact of a novel variant identified in GAD1 through protein modeling. METHODS: A consanguineous family affected with intellectual disability was enrolled. Whole-exome sequencing was performed on an affected individual, followed by bioinformatics analysis including alignment to the GRCh38 reference genome, variant calling, and annotation. Variants were filtered based on rarity, predicted functional impact, and autosomal recessive inheritance pattern. Candidate variants were validated and assessed by Sanger sequencing and segregation analysis. Protein modeling was performed to evaluate the structural impact of the identified variant. RESULTS: A novel homozygous missense variant NM_000817:c.1700G>A;p.Arg567Gln in GAD1 was identified. Segregation analysis confirmed co-segregation of the variant with the affected phenotype. Protein modeling suggested that the variant may disrupt GAD1 enzymatic function involved in gamma-aminobutyric acid synthesis. CONCLUSION: This study emphasizes the significance of genetic investigation in familial cases and the crucial role that GAD1 mutations play in neurodevelopmental disorders with intellectual disability. The results advance the knowledge of molecular causes of ARID and broaden the mutational range.

Pakistani↗

Analysis of linkage disequilibrium in gamma-aminobutyric acid receptor subunit genes in autistic disorder.

Autistic disorder (AD) is a neurodevelopmental disorder characterized by abnormalities in behavior, communication, and social interactions and functioning. Recently, Cook et al. reported significant linkage disequilibrium with an AD susceptibility locus and a marker, GABRB3 155CA-2, in the gamma-aminobutyric acid(A) (GABA(A)) receptor beta3-subunit gene on chromosome 15q11-q13. This linkage disequilibrium was detected using a multiallelic version of the transmission/disequilibrium test (TDT) in a sample of nuclear families having at least one child with autistic disorder. In an attempt to replicate this finding we tested for linkage disequilibrium with this marker, as well as with three additional markers in and around the GABA(A) receptor beta3-subunit gene, in an independent, clinically comparable set of AD families. Unlike Cook et al., we failed to detect significant linkage disequilibrium between GABRB3 155CA-2 and AD in our sample. We did, however, find suggestive evidence for linkage disequilibrium with a marker, GABRB3, approximately 60 kb beyond the 3' end of beta3-subunit gene. This finding lends support for previous reports implicating the involvement of genes in this region with AD. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:43-48, 2000

Autistic Disorder↗

Genomic screen and follow-up analysis for autistic disorder.

Autistic disorder (AutD) is a neurodevelopmental disorder characterized by significant impairment in social, communicative, and behavioral functioning. A genetic basis for AutD is well established with as many as 10 genes postulated to contribute to its underlying etiology. We have completed a genomic screen and follow-up analysis to identify potential AutD susceptibility loci. In stage one of the genome screen, 52 multiplex families (two or more AutD affected individuals/family) were genotyped with 352 genetic markers to yield an approximately 10 centimorgan (cM) grid, inclusive of the X chromosome. The selection criterion for follow-up of interesting regions was a maximum heterogeneity lod score (MLOD) or a maximum nonparametric sib pair lod score (MLS) of at least 1.0. Eight promising regions were identified on chromosomes 2, 3, 7, 15, 18, 19, and X. In the stage two follow-up study we analyzed an additional 47 multiplex families (total=99 families). Regions on chromosomes 2, 3, 7, 15, 19, and X remained interesting (MLOD> or =1.0) in stage two analysis. The peak lod score regions on chromosomes 2, 7, 15, 19, and X overlap previously reported peak linkage areas. The region on chromosome 3 is unique.

Adult↗

No association between the WNT2 gene and autistic disorder.

Autistic disorder is a pervasive neurodevelopmental disorder characterized by deficits in language and social communication, as well as stereotyped patterns of behavior. Peak LOD scores from several genomic screening efforts indicate the presence of an autistic disorder susceptibility locus within the distal long arm of human chromosome 7 (7q31-q35). Wassink et al. [2001: Am J Med Genet 105:406-413] reported that WNT2, located at 7q31, influences genetic risk in autistic disorder. These findings were enhanced when examined in a subset of families with severe language impairment. WNT genes encode secreted growth factor-like proteins that participate in growth regulation, differentiation, and tumorigenesis. We tested for genetic association of two WNT2 variants in an independent data set of 135 singleton and 82 multiplex families. No significant association was found between autistic disorder and the WNT2 genotypes in either the overall data set or in the language-impaired subset of families. However, differences in allele frequencies of the 3' UTR single nucleotide polymorphism between the present population and that of Wassink et al. may account for the inability to detect association between WNT2 and autistic disorder in the present data set. We also screened the two reported autistic disorder mutations previously detected by Wassink et al. We did not identify any activating mutation in the coding region of the WNT2 gene. Thus, we conclude that activating mutations of the WNT2 gene are not a major contributor to the development of autistic disorder in these data.

Adolescent↗

Autistic disorder and chromosome 15q11-q13: construction and analysis of a BAC/PAC contig.

Autistic disorder (AD) is a neurodevelopmental disorder that affects approximately 2-10/10,000 individuals. Chromosome 15q11-q13 has been implicated in the genetic etiology of AD based on (1) cytogenetic abnormalities; (2) increased recombination frequency in this region in AD versus non-AD families; (3) suggested linkage with markers D15S156, D15S219, and D15S217; and (4) evidence for significant association with polymorphisms in the gamma-aminobutyric acid receptor subunit B3 gene (GABRB3). To isolate the putative 15q11-q13 candidate AD gene, a genomic contig and physical map of the approximately 1.2-Mb region from the GABA receptor gene cluster to the OCA2 locus was generated. Twenty-one bacterial artificial chromosome (BAC) clones, 32 P1-derived artificial chromosome (PAC) clones, and 2 P1 clones have been isolated using the markers D15S540, GABRB3, GABRA5, GABRG3, D15S822, and D15S217, as well as 34 novel markers developed from the end sequences of BAC/PAC clones. In contrast to previous findings, the markers D15S822 and D15S975 have been localized within the GABRG3 gene, which we have shown to be approximately 250 kb in size. NotI and numerous EagI restriction enzyme cut sites were identified in this region. The BAC/PAC genomic contig can be utilized for the study of genomic structure and the identification and characterization of genes and their methylation status in this autism candidate gene region on human chromosome 15q11-q13.

Autistic Disorder↗

Parental perspectives on the causes of an autism spectrum disorder in their children.

Autism Spectrum Disorders (ASDs) are complex neurodevelopmental disorders with many biological causes, including genetic, syndromic and environmental. Such etiologic heterogeneity impacts considerably upon parents' needs for understanding their child's diagnosis. A descriptive survey was designed to investigate parental views on the cause(s) of ASD in their child. Among the 41 parents who replied to the questionnaire, genetic influences (90.2%), perinatal factors (68.3%), diet (51.2%), prenatal factors (43.9%) and vaccines (40.0%) were considered to be the most significant contributory factors. Parents reported inaccurately high recurrence risks, misperceptions of the contribution of various putative factors, feelings of guilt and blame regarding their child's diagnosis, as well as a lack of advocacy for genetic counseling by non-geneticist professionals. This study offers clinicians and researchers further insight into what parents believe contributed to their child's diagnosis of ASD and will help facilitate genetic counseling for these families.

Autistic Disorder↗

Signal transducer and activator of transcription 6 (STAT6) and attention-deficit hyperactivity disorder: a speculative hypothesis.

Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by hyperactivity, impulsiveness and inattention that begins in childhood. The underlying pathogenesis of this disorder is still unknown, although pharmacological, genetic and neuroimaging studies suggest that dopamine transportation may be implicated in the pathogenesis of ADHD. Signal transducer and activator of transcription 6 (STAT6), similar to other members of the signal transducer and activator of transcription family of proteins, is an important molecule in the induction and regulation of the immune response. Animal studies have demonstrated that STAT6 is highly expressed in the CNS, especially in the developing brain. Recent studies have demonstrated that STAT6-deficient mice exhibit increased locomotor activity and decreased levels of dopamine transporter expression in the striatum, when compared with the wild-type. From these findings, and evidence from other studies, it can be proposed that STAT6 may be implicated in the pathogenesis of ADHD. Several proposals to test this hypothesis are suggested; attempts to prove the STAT6-ADHD hypothesis may provide a new direction that elucidates the pathogenesis of and a treatment for ADHD.

Animals↗

Effect of neurofeedback training on the neural substrates of selective attention in children with attention-deficit/hyperactivity disorder: a functional magnetic resonance imaging study.

Attention Deficit Hyperactivity Disorder (AD/HD) is a neurodevelopmental disorder mainly characterized by impairments in cognitive functions. Functional neuroimaging studies carried out in individuals with AD/HD have shown abnormal functioning of the anterior cingulate cortex (ACC) during tasks involving selective attention. In other respects, there is mounting evidence that neurofeedback training (NFT) can significantly improve cognitive functioning in AD/HD children. In this context, the present functional magnetic resonance imaging (fMRI) study was conducted to measure the effect of NFT on the neural substrates of selective attention in children with AD/HD. Twenty AD/HD children--not taking any psychostimulant and without co-morbidity-participated to the study. Fifteen children were randomly assigned to the Experimental (EXP) group (NFT), whereas the other five children were assigned to the Control (CON) group (no NFT). Subjects from both groups were scanned 1 week before the beginning of the NFT (Time 1) and 1 week after the end of this training (Time 2), while they performed a Counting Stroop task. At Time 1, for both groups, the Counting Stroop task was associated with significant loci of activation in the left superior parietal lobule. No activation was noted in the ACC. At Time 2, for both groups, the Counting Stroop task was still associated with significant activation of the left superior parietal lobule. This time, however, for the EXP group only there was a significant activation of the right ACC. These results suggest that in AD/HD children, NFT has the capacity to normalize the functioning of the ACC, the key neural substrate of selective attention.

Attention↗

Phenotypic homogeneity provides increased support for linkage on chromosome 2 in autistic disorder.

Autistic disorder (AutD) is a neurodevelopmental disorder characterized by significant disturbances in social, communicative, and behavioral functioning. A two-stage genomic screen analysis of 99 families with AutD revealed suggestive evidence for linkage to chromosome 2q (D2S116 nonparametric sib-pair LOD score [MLS] 1.12 at 198 cM). In addition, analysis of linkage disequilibrium for D2S116 showed an allele-specific P value of <.01. Recently, linkage to the same region of 2q was reported in an independent genome screen. This evidence for linkage increased when analysis was restricted to the subset of patients with AutD who had delayed onset (>36 mo) of phrase speech (PSD). We similarly classified our data set of 82 sib pairs with AutD, identifying 45 families with AutD and PSD. Analysis of this PSD subset increased our support for linkage to 2q (MLS 2.86 and HLOD 2.12 for marker D2S116). These data support evidence for a gene on chromosome 2 contributing to risk of AutD, and they suggest that phenotypic homogeneity increases the power to find susceptibility genes for AutD.

Age of Onset↗

Anatomical differences in the mirror neuron system and social cognition network in autism.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder associated with impaired social and emotional skills, the anatomical substrate of which is still unknown. In this study, we compared a group of 14 high-functioning ASD adults with a group of controls matched for sex, age, intelligence quotient, and handedness. We used an automated technique of analysis that accurately measures the thickness of the cerebral cortex and generates cross-subject statistics in a coordinate system based on cortical anatomy. We found local decreases of gray matter in the ASD group in areas belonging to the mirror neuron system (MNS), argued to be the basis of empathic behavior. Cortical thinning of the MNS was correlated with ASD symptom severity. Cortical thinning was also observed in areas involved in emotion recognition and social cognition. These findings suggest that the social and emotional deficits characteristic of autism may reflect abnormal thinning of the MNS and the broader network of cortical areas subserving social cognition.

Adult↗

Magnetic resonance spectroscopy in psychiatry: basic principles and applications.

In vivo magnetic resonance spectroscopy (MRS) is a safe and non-invasive tool which can be used to study aspects of brain chemistry and metabolism. Although a relatively recent technique in the field of psychiatric research, it has already been used in the study of anxiety and affective disorders, dementia, schizophrenia, and neurodevelopmental disorders. This review outlines the basic principles of MRS and summarises the research findings in psychiatric disorders. Although mostly preliminary, these findings highlight the capacity of MRS to detect subtle neurobiological abnormalities in mental disorders. They also suggest a future role for MRS in differential diagnosis and monitoring illness progression. Initial MRS studies have also focused on the metabolic effects of psychiatric treatments and could provide information about their relationship to clinical variables.

Brain Chemistry↗

Mutation screening and association study of the UBE2H gene on chromosome 7q32 in autistic disorder.

Autistic disorder is a severe neurodevelopmental disorder most probably caused by a complex interaction of genetic factors. Several genomewide scans identified multipoint LOD score peaks in region 7q32. In this region, UBE2H encodes an E2 enzyme of the ubiquitin-dependent proteolytic system. Mutations in another member of this system, the UBE3A gene, cause Angelman syndrome. The participation of E2 (ubiquitin-conjugating enzymes) or E3 (ubiquitin ligases) enzymes in neural development recently emerged. Given its physical location and function, we examined UBE2H as a candidate for involvement in autistic disorder. We confirmed by reverse transcription-polymerase chain reaction that the UBE2H gene was expressed in the rat and the human central nervous system. The rat UBE2H and human UBE2H deduced amino acid sequences are identical. We screened the seven exons of the UBE2H gene in autistic patients using single-strand conformation analysis. We observed a silent A-->G transition at position 336. A case-control association study was performed using this A/G polymorphism. A significant association was found between the G allele and a subgroup of autistic patients with developmental quotient higher than 30 (P=0.004). Although further studies are required, these results suggest that the UBE2H gene could be one of the 7q-susceptibility loci for autistic disorder.

Autistic Disorder↗

Comparison of clinical efficacy and gut microbiota characteristics in children with ASD treated with fecal microbiota transplantation and ketogenic diet.

OBJECTIVE: Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterized by impairments in social communication and interaction, along with restricted, repetitive patterns of behavior. It is often accompanied by gastrointestinal dysfunction and gut microbiota dysbiosis. Fecal Microbiota Transplantation (FMT) and the Ketogenic Diet (KD) are interventions targeting the gut microbiota for ASD. METHODS: 30 participants were diagnosed with ASD according to DSM-5 and ADOS-2. ASD core symptoms were evaluated with CARS and ABC. Gut microbiota composition was analyzed by shotgun metagenomic sequencing. RESULTS: Both groups demonstrated significant improvements in core symptoms. In the FMT group, the mean CARS score significantly decreased from 34.87 to 33.53 (p&#x2009;<&#x2009;0.01); in the KD group, it declined from 35.13 to 33 (p&#x2009;<&#x2009;0.01). The mean ABC score reduced from 79.93 to 69.33 (p&#x2009;=&#x2009;0.064) in the FMT group and from 63.07 to 42.73 (p&#x2009;<&#x2009;0.01) in the KD group. Following the intervention, no statistically significant changes were observed in &#x3b1;-diversity or &#x3b2;-diversity within either group. LEfSe analysis revealed distinct post-intervention microbial signatures: FMT significantly enriched butyrate-producing taxa (Wujia chipingensis, Eubacterium sp. MSJ-33, and Butyrivibrio crossotus), while KD elevated Blautia massiliensis and decreased propionate metabolism -associated taxa (Veillonella sp. S12025-13 and Veillonella nakazawae). KEGG enrichment analysis revealed that KD enriched propionate metabolism (Fold enrichment&#x2009;=&#x2009;3.747, q&#x2009;=&#x2009;0.010) and aromatic compound degradation (Fold enrichment&#x2009;=&#x2009;3.591, q&#x2009;=&#x2009;0.010). CONCLUSIONS: Both interventions significantly improved clinical symptoms among children with ASD, potentially through distinct patterns of gut microbiota modulation. CLINICAL TRIALS NUMBER: NCT06348433 (03/21/2024).

Child↗

Autism, an extreme challenge to integrative medicine. Part: 1: The knowledge base.

Autism, archetype of the autistic spectrum disorders (ASD), is a neurodevelopmental disorder characterized by socially aloof behavior and impairment of language and social interaction. Its prevalence has surged in recent years. Advanced functional brain imaging has confirmed pervasive neurologic involvement. Parent involvement in autism management has accelerated understanding and treatment. Often accompanied by epilepsy, cognitive deficits, or other neurologic impairment, autism manifests in the first three years of life and persists into adulthood. Its etiopathology is poorly defined but likely multifactorial with heritability playing a major role. Prenatal toxic exposures (teratogens) are consistent with autism spectrum symptomatology. Frequent vaccinations with live virus and toxic mercurial content (thimerosal) are a plausible etiologic factor. Autistic children frequently have abnormalities of sulfoxidation and sulfation that compromise liver detoxification, which may contribute to the high body burden of xenobiotics frequently found. Frequent copper-zinc imbalance implies metallothionein impairment that could compound the negative impact of sulfur metabolism impairments on detoxification and on intestinal lining integrity. Intestinal hyperpermeability manifests in autistic children as dysbiosis, food intolerances, and exorphin (opioid) intoxication, most frequently from casein and gluten. Immune system abnormalities encompass derangement of antibody production, skewing of T cell subsets, aberrant cytokine profiles, and other impairments consistent with chronic inflammation and autoimmunity. Coagulation abnormalities have been reported. Part 2 of this review will attempt to consolidate progress in integrative management of autism, aimed at improving independence and lifespan for people with the disorder.

Autistic Disorder↗

[Hereditary factors in attention deficit hyperactivity disorder].

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by concentration problems, hyperactivity and impulsivity. Disturbances in dopamine and/or noradrenalin neurotransmission are probably the underlying pathophysiological mechanisms of ADHD. Around 80% of variants of the phenotype can be ascribed to hereditary factors. There are various chromosomal loci containing ADHD genes. They partially overlap the loci found in linkage studies on dyslexia and autism. It seems likely that a number of genetic variants, each with a small effect size, in combination with gene-environment interactions predispose to ADHD. There is a high degree of phenotypical heterogeneity among people with ADHD. Finding endophenotypes may improve the power of genetic studies. Endophenotypes are specific expressions of the underlying pathophysiology, intermediate between gene and phenotype. Neuro-imaging studies in children with ADHD have indicated abnormalities in frontostriatal, temporal and cerebellar volume. Unaffected brothers and sisters show the same cerebral abnormalities, but not the cerebellar abnormalities. These brain abnormalities together with specific neuropsychological features could be ADHD endophenotypes.

Attention Deficit Disorder with Hyperactivity↗

A conceptual approach to placental pathology and pregnancy outcome.

This report focuses on the relationship of placental pathology to unfavorable pregnancy outcome. Relevant literature is cited and data from the author's investigations are reported and tabulated. The reader will find detailed information on placental lesions that have not been completely investigated or discussed previously. Particular considerations include placental meconium staining, edema, acute and chronic intrauterine infections, placental fetal vasculopathy with fetal nucleated red blood cells, and chorangiosis or other placental dysmaturity. These pathologic changes often signify the pathogenesis of cerebral palsy and other developmental disorders. Almost 90% of neurodevelopmental disorders are initiated before the intrapartum period. Prenatal asphyxia or severe chronic fetal hypoxia are probably present therein. Most investigations of these afflictions are invalid because they do not include placental study with well-designed epidemiologic methods. The pathologic placental findings that are most strongly associated with perinatal asphyxia include chronic ischemic changes, fetal nucleated red blood cells, intravillous hemorrhage, fetal fibrin vascular intimal cushions, meconium staining, and placental intervillous fibrin. Chorioamnionitis is a pathologic entity rather than a clinical syndrome as defined by obstetricians. When it causes severe prematurity, chorioamnionitis is also associated with cerebral palsy.

Asphyxia Neonatorum↗