| 1. |
- Arora, Abishek, et al.
(author)
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Screening autism-associated environmental factors in differentiating human neural progenitors with fractional factorial design-based transcriptomics
- 2023
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In: Scientific Reports. - : Springer Nature. - 2045-2322. ; 13
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Journal article (peer-reviewed)abstract
- Research continues to identify genetic variation, environmental exposures, and their mixtures underlying different diseases and conditions. There is a need for screening methods to understand the molecular outcomes of such factors. Here, we investigate a highly efficient and multiplexable, fractional factorial experimental design (FFED) to study six environmental factors (lead, valproic acid, bisphenol A, ethanol, fluoxetine hydrochloride and zinc deficiency) and four human induced pluripotent stem cell line derived differentiating human neural progenitors. We showcase the FFED coupled with RNA-sequencing to identify the effects of low-grade exposures to these environmental factors and analyse the results in the context of autism spectrum disorder (ASD). We performed this after 5-day exposures on differentiating human neural progenitors accompanied by a layered analytical approach and detected several convergent and divergent, gene and pathway level responses. We revealed significant upregulation of pathways related to synaptic function and lipid metabolism following lead and fluoxetine exposure, respectively. Moreover, fluoxetine exposure elevated several fatty acids when validated using mass spectrometry-based metabolomics. Our study demonstrates that the FFED can be used for multiplexed transcriptomic analyses to detect relevant pathway-level changes in human neural development caused by low-grade environmental risk factors. Future studies will require multiple cell lines with different genetic backgrounds for characterising the effects of environmental exposures in ASD.
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| 2. |
- Bussu, Giorgia, et al.
(author)
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The latent structure of emerging cognitive abilities : An infant twin study
- 2023
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In: Intelligence. - : Elsevier. - 0160-2896 .- 1873-7935. ; 99, s. 101771-101771
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Journal article (peer-reviewed)abstract
- It is well known that genetic factors account for up to 70% of variability in cognition from childhood to adulthood. However, less is known about the first year of life. This study investigated the etiological factors influencing individual variability in different domains of emerging cognitive and motor abilities in early infancy, and to what extent genetic and environmental influences are unique or shared across different domains. We compared multivariate twin models built on scores from the five scales of the Mullen Scales of Early Learning (MSEL) in a community sample of monozygotic and dizygotic twins at 5 months of age (n=567). The results indicated a hierarchical etiological structure whereby a general genetic latent factor accounted for 54% of variance underlying the different domains of emerging cognitive and motor abilities (A=0.54, confidence interval CI=[0; 0.82]). We also found additional genetic influences that were specific to early motor and language development. Unlike previous findings on older children, we did not find significant influences of shared environment on the shared factor (C=0, CI=[0, 0.57]), or any specific scale. Furthermore, influences of unique environment, which include measurement error, were moderate and statistically significant (E=0.46, CI=0.18; 0.81]). This study provides strong evidence for a unitary hierarchical structure across different domains of emerging cognition. Evidence that a single common etiological factor, which we term infant g, contributes to a range of different abilities supports the view that in young infants, intrinsic and general neurodevelopmental processes are key drivers of observable behavioural differences in specific domains.
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| 3. |
- Etemadikhah, Mitra
(author)
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Gene and pathway associations in neurodevelopmental disorders
- 2021
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Doctoral thesis (other academic/artistic)abstract
- Neurodevelopmental disorders are complex and heterogenous disorders affecting brain development. In this thesis, we study intellectual disability (ID) and schizophrenia, and we applied genomic, transcriptomic, and proteomic techniques to identify and further investigate candidate variants and important genes and pathways involved in pathology of these two disorders.In paper I, genotyping and exome analyses were performed in a large multi-generational family with non-syndromic ID from a North Swedish isolate, with the aim to identify linkage regions and disease-associated variants. The linkage analysis identified four suggestive linkage regions. The exome sequencing revealed a known pathogenic mutation in the SLC17A5 gene, and potential pathogenic CNVs overlapping the genes KDM3B and MAP3K4/AGPAT4. The overall results indicated that ID is genetically heterogeneous in this family. In paper II, transcriptome sequencing was performed on fibroblast cells from schizophrenia patients and control individuals from a large family in a genetically isolated region in northern Sweden. We detected 48 significant differentially expressed genes, of which eight genes were previously associated with schizophrenia. These results provide further support for the use of fibroblasts, and highlight benefit of using isolated populations in studies of neurodevelopmental disorders.In paper III, transcriptome sequencing was performed on a large cohort of post-mortem brain tissue samples from schizophrenia patients and controls. In total, 71 significant differentially expressed genes were detected, and gene ontology analysis showed enrichment of genes from the immune system and more specifically the complement system. Our results implicate significant upregulation of complement genes in a subset of the patients.In paper IV, we performed further proteomic analysis on the same sample set as paper III. The primary results from proximity extension assays show significant differential expression of schizophrenia-associated proteins in a subgroup of patients. In total, 21 differentially expressed proteins were identified by the immune panel, 12 proteins by the inflammation panel, and two by the custom panel. The protein IL6 was included in all three panels and consistently showed significant expression changes. Our transcriptome and proteome results highlight the important role of immune system in schizophrenia pathology.
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| 4. |
- Hardiansyah, Irzam, et al.
(author)
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Determining Zygosity in Infant Twins – Revisiting the Questionnaire Approach
- 2021
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In: Twin Research and Human Genetics. - : Cambridge University Press. - 1832-4274 .- 1839-2628. ; 24:3, s. 168-175
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Journal article (peer-reviewed)abstract
- Accurate zygosity determination is a fundamental step in twin research. Although DNA-based testing is the gold standard for determining zygosity, collecting biological samples is not feasible in all research settings or all families. Previous work has demonstrated the feasibility of zygosity estimation based on questionnaire (physical similarity) data in older twins, but the extent to which this is also a reliable approach in infancy is less well established. Here, we report the accuracy of different questionnaire-based zygosity determination approaches (traditional and machine learning) in 5.5 month-old twins. The participant cohort comprised 284 infant twin pairs (128 dizygotic and 156 monozygotic) who participated in the Babytwins Study Sweden (BATSS). Manual scoring based on an established technique validated in older twins accurately predicted 90.49% of the zygosities with a sensitivity of 91.65% and specificity of 89.06%. The machine learning approach improved the prediction accuracy to 93.10%, with a sensitivity of 91.30% and specificity of 94.29%. Additionally, we quantified the systematic impact of zygosity misclassification on estimates of genetic and environmental influences using simulation-based sensitivity analysis on a separate data set to show the implication of our machine learning accuracy gain. In conclusion, our study demonstrates the feasibility of determining zygosity in very young infant twins using a questionnaire with four items and builds a scalable machine learning model with better metrics, thus a viable alternative to DNA tests in large-scale infant twin studies.
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| 5. |
- Koido, Kati, et al.
(author)
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Lack of guidelines and translational knowledge is hindering the implementation of psychiatric genetic counseling and testing within Europe : A multi-professional survey study
- 2023
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In: European Journal of Medical Genetics. - : Elsevier. - 1769-7212 .- 1878-0849. ; 66:8
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Journal article (peer-reviewed)abstract
- Genetic research has identified a large number of genetic variants, both rare and common, underlying neurodevelopmental disorders (NDD) and major psychiatric disorders. Currently, these findings are being translated into clinical practice. However, there is a lack of knowledge and guidelines for psychiatric genetic testing (PsychGT) and genetic counseling (PsychGC). The European Union-funded COST action EnGagE (CA17130) network was started to investigate the current implementation status of PsychGT and PsychGC across 35 participating European countries. Here, we present the results of a pan-European online survey in which we gathered the opinions, knowledge, and practices of a self-selected sample of professionals involved/interested in the field.We received answers from 181 respondents. The three main occupational categories were genetic counselor (21.0%), clinical geneticist (24.9%), and researcher (25.4%). Of all 181 respondents, 106 provide GC for any psychiatric disorder or NDD, corresponding to 58.6% of the whole group ranging from 43.2% in Central Eastern Europe to 66.1% in Western Europe. Overall, 65.2% of the respondents reported that genetic testing is offered to individuals with NDD, and 26.5% indicated the same for individuals with major psychiatric disorders. Only 22.1% of the respondents indicated that they have guidelines for PsychGT. Pharmacogenetic testing actionable for psychiatric disorders was offered by 15%. Interestingly, when genetic tests are fully covered by national health insurance, more genetic testing is provided for individuals with NDD but not those with major psychiatric disorders.Our qualitative analyses of responses highlight the lack of guidelines and knowledge on utilizing and using genetic tests and education and training as the major obstacles to implementation. Indeed, the existence of psychiatric genetic training courses was confirmed by only 11.6% of respondents. The question on the relevance of up-to-date education and training in psychiatric genetics on everyday related practice was highly relevant.We provide evidence that PsychGC and PsychGT are already in use across European countries, but there is a lack of guidelines and education. Harmonization of practice and development of guidelines for genetic counseling, testing, and training professionals would improve equality and access to quality care for individuals with psychiatric disorders within Europe.
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| 6. |
- Li, Danyang, et al.
(author)
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Rare variants in the outcome of social skills group training for autism
- 2022
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In: Autism Research. - : Wiley. - 1939-3792 .- 1939-3806. ; 15:3, s. 434-446
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Journal article (peer-reviewed)abstract
- Exome sequencing has been proposed as the first-tier genetic testing in autism spectrum disorder (ASD). Here, we performed exome sequencing in autistic individuals with average to high intellectual abilities (N = 207) to identify molecular diagnoses and genetic modifiers of intervention outcomes of social skills group training (SSGT) or standard care. We prioritized variants of clinical significance (VCS), variants of uncertain significance (VUS) and generated a pilot scheme to calculate genetic scores of rare and common variants in ASD-related gene pathways. Mixed linear models were used to test the association between the carrier status of VCS/VUS or the genetic scores with intervention outcomes measured by the social responsiveness scale. Additionally, we combined behavioral and genetic features using a machine learning (ML) model to predict the individual response. We showed a rate of 4.4% and 11.3% of VCS and VUS in the cohort, respectively. Individuals with VCS or VUS had improved significantly less after standard care than non-carriers at post-intervention (β = 9.35; p = 0.036), while no such association was observed for SSGT (β = −2.50; p = 0.65). Higher rare variant genetic scores for synaptic transmission and regulation of transcription from RNA polymerase II were separately associated with less beneficial (β = 8.30, p = 0.0044) or more beneficial (β = −6.79, p = 0.014) effects after SSGT compared with standard care at follow-up, respectively. Our ML model showed the importance of rare variants for outcome prediction. Further studies are needed to understand genetic predisposition to intervention outcomes in ASD.
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| 7. |
- Li, Danyang, et al.
(author)
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The influence of common polygenic risk and gene sets on social skills group training response in autism spectrum disorder
- 2020
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In: NPJ Genomic Medicine. - : Nature Publishing Group. - 2056-7944. ; 5:1
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Journal article (peer-reviewed)abstract
- Social skills group training (SSGT) is a frequently used behavioral intervention in autism spectrum disorder (ASD), but the effects are moderate and heterogeneous. Here, we analyzed the effect of polygenic risk score (PRS) and common variants in gene sets on the intervention outcome. Participants from the largest randomized clinical trial of SSGT in ASD to date were selected (N = 188, 99 from SSGT, 89 from standard care) to calculate association between the outcomes in the SSGT trial and PRSs for ASD, attention-deficit hyperactivity disorder (ADHD), and educational attainment. In addition, specific gene sets were selected to evaluate their role on intervention outcomes. Among all participants in the trial, higher PRS for ADHD was associated with significant improvement in the outcome measure, the parental-rated Social Responsiveness Scale. The significant association was due to better outcomes in the standard care group for individuals with higher PRS for ADHD (post-intervention: β = −4.747, P = 0.0129; follow-up: β = −5.309, P = 0.0083). However, when contrasting the SSGT and standard care group, an inferior outcome in the SSGT group was associated with higher ADHD PRS at follow-up (β = 6.67, P = 0.016). Five gene sets within the synaptic category showed a nominal association with reduced response to interventions. We provide preliminary evidence that genetic liability calculated from common variants could influence the intervention outcomes. In the future, larger cohorts should be used to investigate how genetic contribution affects individual response to ASD interventions.
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| 8. |
- Mastropasqua, Francesca, et al.
(author)
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Deficiency of the Heterogeneous Nuclear Ribonucleoprotein U locus leads to delayed hindbrain neurogenesis.
- 2023
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In: Biology open. - : The Company of Biologists. - 2046-6390. ; 12:10
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Journal article (peer-reviewed)abstract
- Genetic variants affecting Heterogeneous Nuclear Ribonucleoprotein U (HNRNPU) have been identified in several neurodevelopmental disorders (NDDs). HNRNPU is widely expressed in the human brain and shows the highest postnatal expression in the cerebellum. Recent studies have investigated the role of HNRNPU in cerebral cortical development, but the effects of HNRNPU deficiency on cerebellar development remain unknown. Here, we describe the molecular and cellular outcomes of HNRNPU locus deficiency during in vitro neural differentiation of patient-derived and isogenic neuroepithelial stem cells with a hindbrain profile. We demonstrate that HNRNPU deficiency leads to chromatin remodeling of A/B compartments, and transcriptional rewiring, partly by impacting exon inclusion during mRNA processing. Genomic regions affected by the chromatin restructuring and host genes of exon usage differences show a strong enrichment for genes implicated in epilepsies, intellectual disability, and autism. Lastly, we show that at the cellular level HNRNPU downregulation leads to an increased fraction of neural progenitors in the maturing neuronal population. We conclude that the HNRNPU locus is involved in delayed commitment of neural progenitors to differentiate in cell types with hindbrain profile.
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| 9. |
- Mataix-Cols, David, et al.
(author)
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In search of environmental risk factors for obsessive-compulsive disorder : study protocol for the OCDTWIN project
- 2023
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In: BMC Psychiatry. - 1471-244X. ; 23:1
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Journal article (peer-reviewed)abstract
- Background: The causes of obsessive-compulsive disorder (OCD) remain unknown. Gene-searching efforts are well underway, but the identification of environmental risk factors is at least as important and should be a priority because some of them may be amenable to prevention or early intervention strategies. Genetically informative studies, particularly those employing the discordant monozygotic (MZ) twin design, are ideally suited to study environmental risk factors. This protocol paper describes the study rationale, aims, and methods of OCDTWIN, an open cohort of MZ twin pairs who are discordant for the diagnosis of OCD. Methods: OCDTWIN has two broad aims. In Aim 1, we are recruiting MZ twin pairs from across Sweden, conducting thorough clinical assessments, and building a biobank of biological specimens, including blood, saliva, urine, stool, hair, nails, and multimodal brain imaging. A wealth of early life exposures (e.g., perinatal variables, health-related information, psychosocial stressors) are available through linkage with the nationwide registers and the Swedish Twin Registry. Blood spots stored in the Swedish phenylketonuria (PKU) biobank will be available to extract DNA, proteins, and metabolites, providing an invaluable source of biomaterial taken at birth. In Aim 2, we will perform within-pair comparisons of discordant MZ twins, which will allow us to isolate unique environmental risk factors that are in the causal pathway to OCD, while strictly controlling for genetic and early shared environmental influences. To date (May 2023), 43 pairs of twins (21 discordant for OCD) have been recruited. Discussion: OCDTWIN hopes to generate unique insights into environmental risk factors that are in the causal pathway to OCD, some of which have the potential of being actionable targets.
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| 10. |
- Mohammad, Salahuddin
(author)
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Investigating mental health disorders in relation to job and living related factors
- 2023
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Licentiate thesis (other academic/artistic)abstract
- Job satisfaction plays an important role for life quality and health of working individuals. While studies have shown that self-reported mental health conditions such as stress, anxiety and depression are associated with job satisfaction, a large population-based study exploring and comparing self-reported physician posed diagnosed conditions and their association with job satisfaction and job tenure is missing. First study addresses the gap along with exploring the impact of the neurotic personality trait and other possible contributing factors.Individuals with autism spectrum disorder (ASD) experience lower well-being as demonstrated epidemiologically mostly for children and adolescents. Further etiological investigation of inclusive wellbeing, in terms of five wellbeing spectrum (5-WBS) traits including neuroticism, depression, loneliness, life satisfaction and positive affect, among adults with ASD may deepen the understanding. Seond study aims to investigate if a genetic predisposition for ASD is associated with 5-WBS traits using polygenic risk score (PRS) analysis.In the first study, sixteen mental health disorders diagnosed by physicians, categorized into four major groups were investigated in relation to employment status (108,711 participants) and in relation to job satisfaction and job tenure (34,808 participants). Analyses were performed using linear regression adjusted for age, sex, TDI, BMI, education, physical activity, work hours and neuroticism. In the second study, PRS for ASD were constructed in the UK Biobank (N = 337,423), based on the GWAS conducted by Psychiatric Genetics Consortium (18,381 cases, 27,969 comparisons) using PRSice-2. First study showed Neurotic & Stress Disorders, Eating Disorders and Other Mental Health Disorders were strongly associated with lower job satisfaction and shorter job tenure in both unadjusted and adjusted analyses. Neuroticism was strongly linked to job satisfaction but was not associated with job tenure. Second study showed, ASD PRS significantly predicted associations with all 5-WBS traits, showing a positive association with the negative WBS traits, neuroticism (max R2 = 0.04%, P < 1x10-4, AUC 0.51), depression (max R2 = 0.06%, P < 1x10-4, AUC 0.51), loneliness (max R2 = 0.04%, P < 1x10-4, AUC 0.51) and a negative association with the positive WBS traits, life satisfaction (max R2 = 0.08%, P < 1x10-4, AUC 0.56), positive affect (max R2 = 0.10%, P < 1x10-4, AUC 0.53).Findings of first study clarify the complex relationship of mental health with job satisfaction and job tenure which is very important to understand in designing measures to improve working life participation of individuals with mental health issues. The findings of second study suggest that adults carrying a high load of susceptible SNPs for ASD are more likely to show a decreased well-being.
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| 11. |
- Portugal, Ana Maria, et al.
(author)
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Infants' looking preferences for social versus non-social objects reflect genetic variation
- 2024
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In: Nature Human Behaviour. - : Springer Nature. - 2397-3374. ; 8:1, s. 115-124
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Journal article (peer-reviewed)abstract
- To what extent do individual differences in infants’ early preference for faces versus non-facial objects reflect genetic and environmental factors? Here in a sample of 536 5-month-old same-sex twins, we assessed attention to faces using eye tracking in two ways: initial orienting to faces at the start of the trial (thought to reflect subcortical processing) and sustained face preference throughout the trial (thought to reflect emerging attention control). Twin model fitting suggested an influence of genetic and unique environmental effects, but there was no evidence for an effect of shared environment. The heritability of face orienting and preference were 0.19 (95% confidence interval (CI) 0.04 to 0.33) and 0.46 (95% CI 0.33 to 0.57), respectively. Face preference was associated positively with later parent-reported verbal competence (β = 0.14, 95% CI 0.03 to 0.25, P = 0.014, R2 = 0.018, N = 420). This study suggests that individual differences in young infants’ selection of perceptual input—social versus non-social—are heritable, providing a developmental perspective on gene–environment interplay occurring at the level of eye movements.
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| 12. |
- Portugal, Ana Maria, et al.
(author)
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Pupil size and pupillary light reflex in early infancy : heritability and link to genetic liability to schizophrenia
- 2022
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In: Journal of Child Psychology and Psychiatry. - : John Wiley & Sons. - 0021-9630 .- 1469-7610. ; 63:9, s. 1068-1077
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Journal article (peer-reviewed)abstract
- Background Measures based on pupillometry, such as the pupillary light reflex (PLR) and baseline pupil size, reflect physiological responses linked to specific neural circuits that have been implicated as atypical in some psychiatric and neurodevelopmental conditions.MethodsWe investigated the contribution of genetic and environmental factors to the baseline pupil size and the PLR in 510 infant twins assessed at 5?months of age (281 monozygotic and 229 dizygotic pairs), and its associations with common genetic variants associated with neurodevelopmental (autism spectrum disorder and attention deficit hyperactivity disorder) and mental health (bipolar disorder, major depressive disorder and schizophrenia) conditions using genome-wide polygenic scores (GPSs).ResultsUnivariate twin modelling showed high heritability at 5?months for both pupil size (h2?=?.64) and constriction in response to light (h2?=?.62), and bivariate twin modeling indicated substantial independence between the genetic factors influencing each (rG?=?.38). A statistically significant positive association between infant tonic pupil size and the GPS for schizophrenia was found (??=?.15, p?=?.024), while there was no significant association with the GPS for autism or any other GPSs.ConclusionsThis study shows that some pupil measures are highly heritable in early infancy, although substantially independent in their genetic etiologies, and associated with common genetic variants linked to schizophrenia. It illustrates how genetically informed studies of infants may help us understand early physiological responses associated with psychiatric disorders which emerge much later in life.
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| 13. |
- Susanto, Evelyn, et al.
(author)
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Modeling SHH-driven medulloblastoma with patient iPS cell-derived neural stem cells
- 2020
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In: Proceedings of the National Academy of Sciences of the United States of America. - : NATL ACAD SCIENCES. - 0027-8424 .- 1091-6490. ; 117:33, s. 20127-20138
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Journal article (peer-reviewed)abstract
- Medulloblastoma is the most common malignant brain tumor in children. Here we describe a medulloblastoma model using In-duced pluripotent stem (iPS) cell-derived human neuroepithelial stem (NES) cells generated from a Gorlin syndrome patient carry-ing a germline mutation in the sonic hedgehog (SHH) receptor PTCH1. We found that Gorlin NES cells formed tumors in mouse cerebellum mimicking human medulloblastoma. Retransplantation of tumor-isolated NES (tNES) cells resulted in accelerated tumor formation, cells with reduced growth factor dependency, en-hanced neurosphere formation in vitro, and increased sensitivity to Vismodegib. Using our model, we identified LGALS1 to be a GLI target gene that is up-regulated in both Gorlin tNES cells and SHH-subgroup of medulloblastoma patients. Taken together, we dem-onstrate that NES cells derived from Gorlin patients can be used as a resource to model medulloblastoma initiation and progression and to identify putative targets.
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| 14. |
- Viktorsson, Charlotte, et al.
(author)
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Infants’ sense of approximate numerosity : Heritability and link to other concurrent traits
- 2023
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In: Developmental Science. - : John Wiley & Sons. - 1363-755X .- 1467-7687. ; 26:4
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Journal article (peer-reviewed)abstract
- Abstract The ability to perceive approximate numerosity is present in many animal species, and emerges early in human infants. Later in life, it is moderately heritable and associated with mathematical abilities, but the etiology of the Approximate Number System (ANS) and its degree of independence from other cognitive abilities in infancy is unknown. Here, we assessed the phenotypic specificity as well as the influence of genetic and environmental factors on the ANS in a sample of 5-month-old twins (N = 514). We found a small-to-moderate but statistically significant effects of genetic factors on ANS acuity (heritability = 0.18, 95% CI: 0.02, 0.33), but only when differences in numerosity were relatively large (1:4 ratio). Non-verbal ability assessed with the Mullen Scales of Early Learning (MSEL) was found to be heritable (0.47; 95% CI: 0.34, 0.57) and the phenotypic association between ANS acuity and non-verbal ability performance was close to zero. Similarly, we found no association between ANS acuity and general attention during the task. An unexpected weak but statistically significant negative association between ANS auity and scores on the receptive language scale of the MSEL was found. These results suggest that early ANS function may be largely independent from other aspects of non-verbal development. Further, variability in ANS in infancy seems to, to some extent, reflect genotypic differences in the population. Assessing 514 infant twins with eye tracking, we found that infant’s sense of approximate numerosity is heritable and not positively associated with concurrent attentional, cognitive or motor abilities. These results have implications for our understanding of development of mathematical ability and the link between cognitive abilities early in postnatal life.
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| 15. |
- Viktorsson, Charlotte, et al.
(author)
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Preferential looking to eyes versus mouth in early infancy : heritability and link to concurrent and later development
- 2023
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In: Journal of Child Psychology and Psychiatry. - : John Wiley & Sons. - 0021-9630 .- 1469-7610. ; 64:2, s. 311-319
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Journal article (peer-reviewed)abstract
- BackgroundFrom birth, infants orient preferentially to faces, and when looking at the face, they attend primarily to eyes and mouth. These areas convey different types of information, and earlier research suggests that genetic factors influence the preference for one or the other in young children. MethodsIn a sample of 535 5-month-old infant twins, we assessed eye (relative to mouth) preference in early infancy, i.e., before neural systems for social communication and language are fully developed. We investigated the contribution of genetic and environmental factors to the preference for looking at eyes, and the association with concurrent traits and follow-up measures. ResultsEye preference was independent from all other concurrent traits measured, and had a moderate-to-high contribution from genetic influences (A = 0.57; 95% CI: 0.45, 0.66). Preference for eyes at 5 months was associated with higher parent ratings of receptive vocabulary at 14 months. No statistically significant association with later autistic traits was found. Preference for eyes was strikingly stable across different stimulus types (e.g., dynamic vs. still), suggesting that infants' preference at this age does not reflect sensitivity to low-level visual cues. ConclusionsThese results suggest that individual differences in infants' preferential looking to eyes versus mouth to a substantial degree reflect genetic variation. The findings provide new leads on both the perceptual basis and the developmental consequences of these attentional biases.
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