The intellectual disability of trisomy 21: differences in gene expression in a case series of patients with lower and higher IQ

Why do individuals with Williams syndrome or Down syndrome fail the Weather Prediction Task?

Williams syndrome (WS) and Down syndrome (DS) are two neurodevelopmental disorders with distinct genetic origins characterized by mild to moderate intellectual disability. Individuals with WS or DS exhibit impaired hippocampus-dependent place learning and enhanced striatum-dependent spatial response learning. Here, we used the Weather Prediction Task (WPT), which can be solved using hippocampus- or striatum-dependent learning strategies, to determine whether individuals with WS or DS exhibit similar profiles outside the spatial domain. Only 10% of individuals with WS or DS solved the WPT. We further assessed whether a concurrent memory task could promote reliance on procedural learning to solve the WPT in individuals with WS but found that the concurrent task did not improve performance. To understand how the probabilistic cue-outcome associations influences WPT performance, and whether individuals with WS or DS can ignore distractors, we assessed performance using a visual learning task with differing reward contingencies, and a modified WPT with unpredictive cues. Both probabilistic feedback and distractors negatively impacted the performance of individuals with WS or DS. These findings are consistent with deficits in hippocampus-dependent learning and executive functions, and reveal the importance of congruent feedback and the minimization of distractors to optimize learning in these two populations.

Suppression of eEF2 phosphorylation alleviates synaptic failure and cognitive deficits in mouse models of Down syndrome

INTRODUCTION

Cognitive impairment is a core feature of Down syndrome (DS), and the underlying neurobiological mechanisms remain unclear. Translation dysregulation is linked to multiple neurological disorders characterized by cognitive impairments. Phosphorylation of the translational factor eukaryotic elongation factor 2 (eEF2) by its kinase eEF2K results in inhibition of general protein synthesis.

METHODS

We used genetic and pharmacological methods to suppress eEF2K in two lines of DS mouse models. We further applied multiple approaches to evaluate the effects of eEF2K inhibition on DS pathophysiology.

RESULTS

We found that eEF2K signaling was overactive in the brain of patients with DS and DS mouse models. Inhibition of eEF2 phosphorylation through suppression of eEF2K in DS model mice improved multiple aspects of DS-associated pathophysiology including de novo protein synthesis deficiency, synaptic morphological defects, long-term synaptic plasticity failure, and cognitive impairments.

DISCUSSION

Our data suggested that eEF2K signaling dysregulation mediates DS-associated synaptic and cognitive impairments.

HIGHLIGHTS

Phosphorylation of the translational factor eukaryotic elongation factor 2 (eEF2) is increased in the Down syndrome (DS) brain. Suppression of the eEF2 kinase (eEF2K) alleviates cognitive deficits in DS models. Suppression of eEF2K improves synaptic dysregulation in DS models. Cognitive and synaptic impairments in DS models are rescued by eEF2K inhibitors.

New Insights into the Education of Children with Congenital Heart Disease with and without Trisomy 21

Background and Objectives: Patients with congenital heart disease (CHD), especially as a concomitant syndromal disease of trisomy 21 (T21), are at risk for impaired neurodevelopment. This can also affect these patients' education. However, there continues to be a research gap in the educational development of CHD patients and T21 CHD patients. Materials and Methods: In total, data from 2873 patients from the German National Register for Congenital Heart Defects were analyzed. The data are based on two online education surveys conducted among patients registered in the National Register for Congenital Heart Defects (2017, 2020). Results: Of 2873 patients included (mean age: 14.1 ± 4.7 years, 50.5% female), 109 (3.8%) were identified with T21 (mean age: 12.9 ± 4.4 years, 49.5% female). T21 CHD participants had a high demand for early specific interventions (overall cohort 49.1%; T21 cohort 100%). T21 CHD children more frequently attended special schools and, compared to non-trisomy 21 (nT21) CHD patients, the probability of attending a grammar school was reduced. In total, 87.1% of nT21 CHD patients but 11% of T21 CHD patients were enrolled in a regular elementary school, and 12.8% of T21 CHD patients could transfer to a secondary school in contrast to 35.5% of nT21 CHD patients. Most of the T21 CHD patients were diagnosed with psychiatric disorders, e.g., learning, emotional, or behavioral disorders (T21 CHD patients: 82.6%; nT21 CHD patients: 31.4%; p < 0.001). Conclusions: CHD patients are at risk for impaired academic development, and the presence of T21 is an aggravating factor. Routine follow-up examinations should be established to identify developmental deficits and to provide targeted interventions.

Evaluation of dental anxiety in children with Down's syndrome using dog-assisted therapy: A pilot study

BACKGROUND

Dental anxiety and fear are the major treatment challenges faced by pediatric dentists. Oral hygiene in children with Down's syndrome is highly compromised in comparison to their healthy counterparts. Animal-assisted therapy, through dogs, has been beneficial in alleviating dental fear and anxiety in healthy pediatric population.

AIM

The aim of the study was to assess the impact of dog-assisted therapy (DAT) on children with Down's syndrome undergoing dental examination and fluoride varnish application in dental operatory.

MATERIALS AND METHODS

Twenty children with Down's syndrome between 5 and 12 years of age were selected. Group A (intervention group): DAT was carried out in the dental operatory. Group B (control group): Dental treatment was performed in the absence of a therapy dog in the dental operatory. Anxiety levels were evaluated by recording the pulse rate and revised modified faces version of the Modified Child Dental Anxiety Scale (MCDAS[f]).

STATISTICAL ANALYSIS

The intergroup comparison of pulse rate was done using an unpaired t-test, whereas the variation in intragroup pulse rate was analyzed using the Analysis of Variance test. The anxiety scores were subjected to a paired t-test for intragroup comparison with P < 0.05 considered to be statistically significant.

RESULTS

Reduction in dental anxiety was observed in the intervention group (P < 0.001).

CONCLUSION

DAT can be used as an effective behavior management technique for children with Down's syndrome undergoing dental examination and simple dental procedures in the dental operatory.

A biophysiological framework exploring factors affecting speech and swallowing in clinical populations: focus on individuals with Down syndrome

Speech and swallowing are complex sensorimotor behaviors accomplished using shared vocal tract anatomy. Efficient swallowing and accurate speech require a coordinated interplay between multiple streams of sensory feedback and skilled motor behaviors. Due to the shared anatomy, speech and swallowing are often both impacted in individuals with various neurogenic and developmental diseases, disorders, or injuries. In this review paper, we present an integrated biophysiological framework for modeling how sensory and motor changes alter functional oropharyngeal behaviors of speech and swallowing, as well as the potential downstream effects to the related areas of language and literacy. We discuss this framework with specific reference to individuals with Down syndrome (DS). Individuals with DS experience known craniofacial anomalies that impact their oropharyngeal somatosensation and skilled motor output for functional oral-pharyngeal activities such as speech and swallowing. Given the increased risk of dysphagia and "silent" aspiration in individuals with DS, it is likely somatosensory deficits are present as well. The purpose of this paper is to review the functional impact of structural and sensory alterations on skilled orofacial behaviors in DS as well as related skills in language and literacy development. We briefly discuss how the basis of this framework can be used to direct future research studies in swallowing, speech, and language and be applied to other clinical populations.

Psychosocial-behavioural interventions for school-aged children with intellectual disabilities: A systematic review of randomised control trials

BACKGROUND

Evidence-based interventions are essential for school-aged children with intellectual disabilities to facilitate development and promote future independence.

METHODS

Using a PRISMA approach, systematic screening of five databases was undertaken. Original randomised controlled studies with psychosocial-behavioural interventions were included where participants were school aged (5-18 yrs) with documented intellectual disability. Study methodology was assessed using the Cochrane RoB 2 tool.

RESULTS

Two thousand three hundred and three records were screened with 27 studies included. Studies mainly included primary school participants with mild intellectual disabilities. Most interventions focused on intellectual skills (e.g., memory, attention, literacy and mathematics) followed by adaptive skills (e.g., daily living, communication, social and education/vocation) and some focused on a combination of these.

CONCLUSION

This review highlights the gap in evidence-base for social, communication and education/vocation interventions with school-aged children with moderate and severe intellectual disability. Future RCTs that bridge this knowledge gap across ages and ability are required for best practice.

Timing of Alzheimer's Disease by Intellectual Disability Level in Down Syndrome

BACKGROUND

Trisomy 21 causes Down syndrome (DS) and is a recognized cause of early-onset Alzheimer's disease (AD).

OBJECTIVE

The current study sought to determine if premorbid intellectual disability level (ID) was associated with variability in age-trajectories of AD biomarkers and cognitive impairments. General linear mixed models compared the age-trajectory of the AD biomarkers PET Aβ and tau and cognitive decline across premorbid ID levels (mild, moderate, and severe/profound), in models controlling trisomy type, APOE status, biological sex, and site.

METHODS

Analyses involved adults with DS from the Alzheimer's Biomarkers Consortium-Down Syndrome. Participants completed measures of memory, mental status, and visuospatial ability. Premorbid ID level was based on IQ or mental age scores prior to dementia concerns. PET was acquired using [11C] PiB for Aβ, and [18F] AV-1451 for tau.

RESULTS

Cognitive data was available for 361 participants with a mean age of 45.22 (SD = 9.92) and PET biomarker data was available for 154 participants. There was not a significant effect of premorbid ID level by age on cognitive outcomes. There was not a significant effect of premorbid ID by age on PET Aβ or on tau PET. There was not a significant difference in age at time of study visit of those with mild cognitive impairment-DS or dementia by premorbid ID level.

CONCLUSION

Findings provide robust evidence of a similar time course in AD trajectory across premorbid ID levels, laying the groundwork for the inclusion of individuals with DS with a variety of IQ levels in clinical AD trials.

Differential Methylation Profile in Fragile X Syndrome-Prone Offspring Mice after in Utero Exposure to Lactobacillus Reuteri

Environmental factors such as diet, gut microbiota, and infections have proven to have a significant role in epigenetic modifications. It is known that epigenetic modifications may cause behavioral and neuronal changes observed in neurodevelopmental disabilities, including fragile X syndrome (FXS) and autism (ASD). Probiotics are live microorganisms that provide health benefits when consumed, and in some cases are shown to decrease the chance of developing neurological disorders. Here, we examined the epigenetic outcomes in offspring mice after feeding of a probiotic organism, Lactobacillus reuteri (L. reuteri), to pregnant mother animals. In this study, we tested a cohort of Western diet-fed descendant mice exhibiting a high frequency of behavioral features and lower FMRP protein expression similar to what is observed in FXS in humans (described in a companion manuscript in this same GENES special topic issue). By investigating 17,735 CpG sites spanning the whole mouse genome, we characterized the epigenetic profile in two cohorts of mice descended from mothers treated and non-treated with L. reuteri to determine the effect of prenatal probiotic exposure on the prevention of FXS-like symptoms. We found several genes involved in different neurological pathways being differentially methylated (p ≤ 0.05) between the cohorts. Among the key functions, synaptogenesis, neurogenesis, synaptic modulation, synaptic transmission, reelin signaling pathway, promotion of specification and maturation of neurons, and long-term potentiation were observed. The results of this study are relevant as they could lead to a better understanding of the pathways involved in these disorders, to novel therapeutics approaches, and to the identification of potential biomarkers for early detection of these conditions.

Efficacy and safety of methylphenidate on attention deficit hyperactivity disorder in children with Down syndrome

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is a common co-morbidity that affects up to 44% of children with Down syndrome (DS). There is a need for reliable, good quality research on the use of methylphenidate within this population. The objective of this study is to report our experience regarding the management of ADHD in these children using methylphenidate.

METHODS

This study is a retrospective observation of 21 children with DS, followed at Jérôme Lejeune Institute between 2000 and 2018. The diagnosis of ADHD was made using the Diagnostic and Statistical Manual of Mental Disorders criteria. Efficacy was measured as response or non-response on two main symptoms: attention/concentration and hyperactivity/impulsivity. Safety was evaluated by the presence or absence of side effects.

RESULTS

Sixteen out of the 21 children (76%) showed improvement with methylphenidate. The average age of treatment onset in responding children was 8 years and 10 months versus 6 years and 3 months in non-responders (P = 0.05). Average dose/weight was significantly different in responders and non-responders (0.82 vs. 0.54 mg/kg/day, respectively; P = 0.03). Twelve children out of 21 (57%) experienced side effects; only three experienced side effects severe enough to require treatment interruption. Most common side effects were loss of appetite and difficulties in falling asleep.

CONCLUSION

Methylphenidate was effective and safe in treating ADHD in 76% of cases in children with DS, with few serious side effects to report. Early diagnosis of ADHD is important to improve the quality of life, learning, inclusion and socialisation of children with DS.

Importance of determining variations in the number of copies in newborns with autosomal aneuploidies

Introducción.

Las aneuploidías son trastornos genéticos frecuentes en la práctica clínica; sin embargo, se conoce poco sobre las otras variantes genéticas que modifican el fenotipo final.

Objetivo.

Determinar las variantes en el número de copias y las regiones con pérdida de heterocigosidad autosómica mayor de 0,5 % o de regiones mayores de 10 Mb en neonatos con aneuploidías autosómicas.

Materiales y métodos.

Se hizo el análisis cromosómico por micromatrices a los neonatos con aneuploidías autosómicas (n=7), trisomía 21 (n=5) y trisomía 18 (n=2) evaluados en los hospitales Antonio Lorena y Regional de Cusco, Perú, en el 2018.

Resultados.

En dos neonatos se encontraron variantes en el número de copias, patogénicas o probablemente patogénicas, en regiones diferentes al cromosoma 21 o al 18. Además, se observaron dos variantes del número de copias con más de 500 kpb de patogenia desconocida.

Conclusiones.

Si bien el número de pacientes era muy reducido, es importante resaltar que se encontraron otras variantes en el número de copias que se han descrito asociadas con trastornos del neurodesarrollo, varias anomalías congénitas, hipoacusia y talla baja o alta, entre otras, lo que probablemente influye negativamente en el fenotipo de este grupo de pacientes.

A Critical Review of Spatial Abilities in Down and Williams Syndromes: Not All Space Is Created Equal

Down syndrome (DS, Trisomy 21) and Williams syndrome (WS) are two neurodevelopmental disorders of genetic origin that are accompanied by mild to moderate intellectual disability but exhibit distinct cognitive profiles. In this review we discuss our recent work characterizing the real-world spatial learning and memory abilities of adult individuals with DS and WS. We used several different paradigms in which participants locomote freely and have access to coherent input from all sensory modalities to investigate their fundamental egocentric (body-centered or viewpoint-dependent) and allocentric (world-centered or viewpoint-independent) spatial abilities. We found unequivocal evidence that most individuals with DS exhibit low-resolution egocentric and allocentric spatial learning and memory abilities similar to typically developing (TD) children in the same mental age range. In contrast, most individuals with DS exhibit impaired high-resolution allocentric spatial learning and facilitated response learning as compared to TD children. In comparison, whereas most individuals with WS also exhibit facilitated response learning, their low-resolution allocentric spatial learning and memory abilities are severely impaired as compared to both TD children and individuals with DS. Together with work from other laboratories using real-world or virtual reality paradigms, these findings indicate that in order to navigate in their environment most individuals with DS may use either egocentric route learning that does not integrate individual landmarks, or a low-resolution allocentric spatial representation that encodes the relationships between different locations (i.e., cognitive mapping). In contrast, since most individuals with WS are unable to build or use a low-resolution allocentric or configural representation of the environment they may use visually and verbally encoded landmarks as beacons to learn routes. Finally, we discuss the main neural structures implicated in these different spatial processes and explain how the relative preservation or impairment of specific brain functions may engender the unique cognitive profiles observed in individuals with these neurodevelopmental disorders.

Intellectual Abilities of Children with Narcolepsy

High cognitive functioning could be a protective factor for school difficulties, behavioral and mood impairments in children with narcolepsy. To investigate this factor, we studied the intellectual abilities of 74 children with narcolepsy (43 boys, 11.7 years old at diagnosis, 91% of cataplexies, 64% obese, 100% HLA positive for DR-DQB1*06:02). All children underwent a one-night polysomnography followed by Multiple Sleep Latency Tests, an evaluation of intelligence quotient (IQ), and filled standardized questionnaires. Thirty-eight percent had high potentialities (HP defined by IQ > 130) and 48% had school difficulties. Using non-parametric tests, we found that HP children reported less difficulties at school and tended to have less impulsivity, conduct, and learning disorders than those without HP. They also tended to be less obese and had less desaturation. Using a multivariate regression analysis, we found an association between the REM sleep percentage and the IQ. REM sleep could be involved in the dynamic changes contributing to the equilibrium of intellectual functioning. This study highlights that despite their frequent school difficulties, narcolepsy per se is unlikely to be a cause of intellectual disability in children. Prompt diagnosis and management of comorbidities such as obesity and obstructive sleep apnea (OSA) could improve cognitive and school performances in these children.

Path Integration and Cognitive Mapping Capacities in Down and Williams Syndromes

Williams (WS) and Down (DS) syndromes are neurodevelopmental disorders with distinct genetic origins and different spatial memory profiles. In real-world spatial memory tasks, where spatial information derived from all sensory modalities is available, individuals with DS demonstrate low-resolution spatial learning capacities consistent with their mental age, whereas individuals with WS are severely impaired. However, because WS is associated with severe visuo-constructive processing deficits, it is unclear whether their impairment is due to abnormal visual processing or whether it reflects an inability to build a cognitive map. Here, we tested whether blindfolded individuals with WS or DS, and typically developing (TD) children with similar mental ages, could use path integration to perform an egocentric homing task and return to a starting point. We then evaluated whether they could take shortcuts and navigate along never-traveled trajectories between four objects while blindfolded, thus demonstrating the ability to build a cognitive map. In the homing task, 96% of TD children, 84% of participants with DS and 44% of participants with WS were able to use path integration to return to their starting point consistently. In the cognitive mapping task, 64% of TD children and 74% of participants with DS were able to take shortcuts and use never-traveled trajectories, the hallmark of cognitive mapping ability. In contrast, only one of eighteen participants with WS demonstrated the ability to build a cognitive map. These findings are consistent with the view that hippocampus-dependent spatial learning is severely impacted in WS, whereas it is relatively preserved in DS.

Methylomic profiling in trisomy 21 identifies cognition- and Alzheimer's disease-related dysregulation

Abstract

Background

Trisomy 21 (T21) is associated with intellectual disability that ranges from mild to profound with an average intellectual quotient of around 50. Furthermore, T21 patients have a high risk of developing Alzheimer’s disease (AD) early in life, characterized by the presence of senile plaques of amyloid protein and neurofibrillary tangles, leading to neuronal loss and cognitive decline. We postulate that epigenetic factors contribute to the observed variability in intellectual disability, as well as at the level of neurodegeneration seen in T21 individuals.

Materials and Methods

A genome-wide DNA methylation study was performed using Illumina Infinium® MethylationEPIC BeadChips on whole blood DNA of 3 male T21 patients with low IQ, 8 T21 patients with high IQ (4 males and 4 females), and 21 age- and sex-matched control samples (12 males and 9 females) in order to determine whether DNA methylation alterations could help explain variation in cognitive impairment between individuals with T21. In view of the increased risk of developing AD in T21 individuals, we additionally investigated the T21-associated sites in published blood DNA methylation data from the AgeCoDe cohort (German study on Ageing, Cognition, and Dementia). AgeCoDe represents a prospective longitudinal study including non-demented individuals at baseline of which a part develops AD dementia at follow-up.

Results

Two thousand seven hundred sixteen differentially methylated sites and regions discriminating T21 and healthy individuals were identified. In the T21 high and low IQ comparison, a single CpG located in the promoter of PELI1 was differentially methylated after multiple testing adjustment. For the same contrast, 69 differentially methylated regions were identified. Performing a targeted association analysis for the significant T21-associated CpG sites in the AgeCoDe cohort, we found that 9 showed significant methylation differences related to AD dementia, including one in the ADAM10 gene. This gene has previously been shown to play a role in the prevention of amyloid plaque formation in the brain.

Conclusion

The differentially methylated regions may help understand the interaction between methylation alterations and cognitive function. In addition, ADAM10 might be a valuable blood-based biomarker for at least the early detection of AD.

Plasma metabolites related to cellular energy metabolism are altered in adults with Down syndrome and Alzheimer's disease

Down syndrome (DS) is a well-known neurodevelopmental disorder most commonly caused by trisomy of chromosome 21. Because individuals with DS almost universally develop heavy amyloid burden and Alzheimer's disease (AD), biomarker discovery in this population may be extremely fruitful. Moreover, any AD biomarker in DS that does not directly involve amyloid pathology may be of high value for understanding broader mechanisms of AD generalizable to the neurotypical population. In this retrospective biomarker discovery study, we examined banked peripheral plasma samples from 78 individuals with DS who met clinical criteria for AD at the time of the blood draw (DS-AD) and 68 individuals with DS who did not (DS-NAD). We measured the relative abundance of approximately 5,000 putative features in the plasma using untargeted mass spectrometry (MS). We found significantly higher levels of a peak putatively annotated as lactic acid in the DS-AD group (q = .014), a finding confirmed using targeted MS (q = .011). Because lactate is the terminal product of glycolysis and subsequent lactic acid fermentation, we performed additional targeted MS focusing on central carbon metabolism which revealed significantly increased levels of pyruvic (q = .03) and methyladipic (q = .03) acids in addition to significantly lower levels of uridine (q = .007) in the DS-AD group. These data suggest that AD in DS is accompanied by a shift from aerobic respiration toward the less efficient fermentative metabolism and that bioenergetically derived metabolites observable in peripheral blood may be useful for detecting this shift.

Dementia in Down syndrome: unique insights for Alzheimer disease research

Virtually all adults with Down syndrome (DS) show the neuropathological changes of Alzheimer disease (AD) by the age of 40 years. This association is partially due to overexpression of amyloid precursor protein, encoded by APP, as a result of the location of this gene on chromosome 21. Amyloid-β accumulates in the brain across the lifespan of people with DS, which provides a unique opportunity to understand the temporal progression of AD and the epigenetic factors that contribute to the age of dementia onset. This age dependency in the development of AD in DS can inform research into the presentation of AD in the general population, in whom a longitudinal perspective of the disease is not often available. Comparison of the risk profiles, biomarker profiles and genetic profiles of adults with DS with those of individuals with AD in the general population can help to determine common and distinct pathways as well as mechanisms underlying increased risk of dementia. This Review evaluates the similarities and differences between the pathological cascades and genetics underpinning DS and AD with the aim of providing a platform for common exploration of these disorders.

Abnormal Microglia and Enhanced Inflammation-Related Gene Transcription in Mice with Conditional Deletion of Ctcf in Camk2a-Cre-Expressing Neurons

CCCTC-binding factor (CTCF) is an 11 zinc finger DNA-binding domain protein that regulates gene expression by modifying 3D chromatin structure. Human mutations in CTCF cause intellectual disability and autistic features. Knocking out Ctcf in mouse embryonic neurons is lethal by neonatal age, but the effects of CTCF deficiency in postnatal neurons are less well studied. We knocked out Ctcf postnatally in glutamatergic forebrain neurons under the control of Camk2a-Cre. Ctcf^loxP/loxP;Camk2a-Cre⁺ (Ctcf CKO) mice of both sexes were viable and exhibited profound deficits in spatial learning/memory, impaired motor coordination, and decreased sociability by 4 months of age. Ctcf CKO mice also had reduced dendritic spine density in the hippocampus and cerebral cortex. Microarray analysis of mRNA from Ctcf CKO mouse hippocampus identified increased transcription of inflammation-related genes linked to microglia. Separate microarray analysis of mRNA isolated specifically from Ctcf CKO mouse hippocampal neurons by ribosomal affinity purification identified upregulation of chemokine signaling genes, suggesting crosstalk between neurons and microglia in Ctcf CKO hippocampus. Finally, we found that microglia in Ctcf CKO mouse hippocampus had abnormal morphology by Sholl analysis and increased immunostaining for CD68, a marker of microglial activation. Our findings confirm that Ctcf KO in postnatal neurons causes a neurobehavioral phenotype in mice and provide novel evidence that CTCF depletion leads to overexpression of inflammation-related genes and microglial dysfunction.SIGNIFICANCE STATEMENT CCCTC-binding factor (CTCF) is a DNA-binding protein that organizes nuclear chromatin topology. Mutations in CTCF cause intellectual disability and autistic features in humans. CTCF deficiency in embryonic neurons is lethal in mice, but mice with postnatal CTCF depletion are less well studied. We find that mice lacking Ctcf in Camk2a-expressing neurons (Ctcf CKO mice) have spatial learning/memory deficits, impaired fine motor skills, subtly altered social interactions, and decreased dendritic spine density. We demonstrate that Ctcf CKO mice overexpress inflammation-related genes in the brain and have microglia with abnormal morphology that label positive for CD68, a marker of microglial activation. Our findings suggest that inflammation and dysfunctional neuron-microglia interactions are factors in the pathology of CTCF deficiency.

Does Congenital Heart Disease Affect Neurodevelopmental Outcomes in Children with Down Syndrome?

OBJECTIVE

The impact that congenital heart disease (CHD) has on the neurodevelopment of children with Down syndrome (DS) is unknown and potentially has implications for targeted early intervention. This study assessed the relationship between CHD that required surgery in the first year of life and neurodevelopmental, behavioral and emotional functioning outcomes in children with DS.

METHODS

A retrospective chart review of 1092 children (0-18 years) with DS who visited a single institution from 8/08-8/13 was performed. Children who underwent at least one of nine neurodevelopmental (cognitive, language, developmental) or academic tests were included in the analysis (N = 178). Cohort was age-divided into infants/toddlers (0-2 years), preschoolers (3-5 years), and school age/adolescent (6-18 years). Test scores of children with DS who underwent cardiac surgery in the first year of life were compared to children with DS without CHD. T test, chi-square and Mann Whitney U tests were used where appropriate.

RESULTS

Infants/toddlers with cardiac surgery had lower scores for receptive (P = .01), expressive (P = .021) and composite language (P < .001) compared to those with no CHD. Preschoolers with cardiac surgery had lower language scores and lower visual motor scores, although not statistically significant. In school age children with cardiac surgery there were no differences in IQ scores, language scores, or academic achievement scores compared to those without CHD. Also at school-age there was no difference in the incidence of ADHD, executive function or on internalizing and externalizing behavior scores.

CONCLUSION

Children with DS undergoing cardiac surgery during the first year demonstrated poorer neurodevelopmental outcomes as infants/toddler but had no difference at school age compared to children with DS without CHD. These results will guide early interventions to optimize neurodevelopmental outcomes in children with DS and will help with family counseling after CHD repair.

A quantitative transcriptome reference map of the normal human brain

We performed an innovative systematic meta-analysis of 60 gene expression profiles of whole normal human brain, to provide a quantitative transcriptome reference map of it, i.e. a reference typical value of expression for each of the 39,250 known, mapped and 26,026 uncharacterized (unmapped) transcripts. To this aim, we used the software named Transcriptome Mapper (TRAM), which is able to generate transcriptome maps based on gene expression data from multiple sources. We also analyzed differential expression by comparing the brain transcriptome with those derived from human foetal brain gene expression, from a pool of human tissues (except the brain) and from the two normal human brain regions cerebellum and cerebral cortex, which are two of the main regions severely affected when cognitive impairment occurs, as happens in the case of trisomy 21. Data were downloaded from microarray databases, processed and analyzed using TRAM software and validated in vitro by assaying gene expression through several magnitude orders by 'real-time' reverse transcription polymerase chain reaction (RT-PCR). The excellent agreement between in silico and experimental data suggested that our transcriptome maps may be a useful quantitative reference benchmark for gene expression studies related to the human brain. Furthermore, our analysis yielded biological insights about those genes which have an intrinsic over-/under-expression in the brain, in addition offering a basis for the regional analysis of gene expression. This could be useful for the study of chromosomal alterations associated to cognitive impairment, such as trisomy 21, the most common genetic cause of intellectual disability.

Association between long non-coding RNA and human rare diseases (Review)

Long non-coding RNAs (lncRNAs) are untranslated transcripts with longer than 200 nucleotides (nt), which possess many of the structural characteristics of mRNAs, including a poly A tail, 5'-capping, and a promoter structure, but no conserved open reading frame. Moreover, lncRNA expression patterns change during differentiation and exhibit a variety of splicing patterns. Many lncRNAs are expressed at specific times and in specific tissues during development. It has been proposed that lncRNAs are involved in the epigenetic regulation of coding genes, and thus exert a powerful effect on a number of physiological and pathological processes, including the pathogenesis of many human rare diseases.

Genetic basis of cohesinopathies

Cohesin is a ring-form multifunctional protein complex, which was discovered during a search for molecules that keep sister chromatids together during segregation of chromosomes during cell division. In the past decade, a large number of results have also demonstrated a need for the cohesin complex in other crucial events in the life cycle of the cell, including DNA duplication, heterochromatin formation, DNA double-strand break repair, and control of gene expression. The dynamics of the cohesin ring are modulated by a number of accessory and regulatory proteins, known as cohesin cofactors. Loss of function of the cohesin complex is incompatible with life; however, mutations in the genes encoding for cohesin subunits and/or cohesin cofactors, which have very little or a null effect on chromosome segregation, represent a newly recognized class of human genetic disorders known as cohesinopathies. A number of genetic, biochemical, and clinical approaches, and importantly, animal models, can help us to determine the underlying mechanisms for these human diseases.

Performance of Down syndrome subjects during a coincident timing task

BACKGROUND

The time synchronization is a very important ability for the acquisition and performance of motor skills that generate the need to adapt the actions of body segments to external events of the environment that are changing their position in space. Down Syndrome (DS) individuals may present some deficits to perform tasks with synchronization demand. We aimed to investigate the performance of individuals with DS in a simple Coincident Timing task.

METHOD

32 individuals were divided into 2 groups: the Down syndrome group (DSG) comprised of 16 individuals with average age of 20 (+/- 5 years old), and a control group (CG) comprised of 16 individuals of the same age. All individuals performed the Simple Timing (ST) task and their performance was measured in milliseconds. The study was conducted in a single phase with the execution of 20 consecutive trials for each participant.

RESULTS

There was a significant difference in the intergroup analysis for the accuracy adjustment - Absolute Error (Z = 3.656, p = 0.001); and for the performance consistence - Variable Error (Z = 2.939, p = 0.003).

CONCLUSION

DS individuals have more difficulty in integrating the motor action to an external stimulus and they also present more inconsistence in performance. Both groups presented the same tendency to delay their motor responses.