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Journal of Neuroscience Research Apr 2023Several non-verbal cognitive and behavioral tests have been developed to assess learning deficits in humans with Down syndrome (DS). Here we used rodent touchscreen...
Several non-verbal cognitive and behavioral tests have been developed to assess learning deficits in humans with Down syndrome (DS). Here we used rodent touchscreen paradigms in adult male mice to investigate visual discrimination (VD) learning and inhibitory control in the Dp(16)1/Yey (C57BL/6J genetic background), Ts65Dn (mixed B6 X C3H genetic background) and Ts1Cje (C57BL/6J genetic background) mouse models of DS. Dp(16)1/Yey and Ts1Cje models did not exhibit motivation or learning deficits during early pre-training, however, Ts1Cje mice showed a significant learning delay after the introduction of the incorrect stimulus (late pre-training), suggesting prefrontal cortex defects in this model. Dp(16)1/Yey and Ts1Cje mice display learning deficits in VD but these deficits were more pronounced in the Dp(16)1/Yey model. Both models also exhibited compulsive behavior and abnormal cortical inhibitory control during Extinction compared to WT littermates. Finally, Ts65Dn mice outperformed WT littermates in pre-training stages by initiating a significantly higher number of trials due to their hyperactive behavior. Both Ts65Dn and WT littermates showed poor performance during late pre-training and were not tested in VD. These studies demonstrate significant learning deficits and compulsive behavior in the Ts1Cje and Dp(16)1/Yey mouse models of DS. They also demonstrate that the mouse genetic background (C57BL/6J vs. mixed B6 X C3H) and the absence of hyperactive behavior are key determinants of successful learning in touchscreen behavioral testing. These data will be used to select the mouse model that best mimics cognitive deficits in humans with DS and evaluate the effects of future therapeutic interventions.
Topics: Humans; Male; Mice; Animals; Down Syndrome; Pilot Projects; Phenotype; Mice, Inbred C57BL; Mice, Inbred C3H; Disease Models, Animal
PubMed: 36602162
DOI: 10.1002/jnr.25160 -
Clinical and Translational Medicine Jul 2023Down syndrome (DS), which is characterized by various malfunctions, is the most common chromosomal disorder. As the DS population continues to grow and most of those...
BACKGROUND
Down syndrome (DS), which is characterized by various malfunctions, is the most common chromosomal disorder. As the DS population continues to grow and most of those with DS live beyond puberty, early-onset health problems have become apparent. However, the cellular landscape and molecular alterations have not been thoroughly studied.
METHODS
This study utilized single-cell resolution techniques to examine DS in humans and mice, spanning seven distinct organs. A total of 71 934 mouse and 98 207 human cells were analyzed to uncover the molecular alterations occurring in different cell types and organs related to DS, specifically starting from the fetal stage. Additionally, SA-β-Gal staining, western blot, and histological study were employed to verify the alterations.
RESULTS
In this study, we firstly established the transcriptomic profile of the mammalian DS, deciphering the cellular map and molecular mechanism. Our analysis indicated that DS cells across various types and organs experienced senescence stresses from as early as the fetal stage. This was marked by elevated SA-β-Gal activity, overexpression of cell cycle inhibitors, augmented inflammatory responses, and a loss of cellular identity. Furthermore, we found evidence of mitochondrial disturbance, an increase in ribosomal protein transcription, and heightened apoptosis in fetal DS cells. This investigation also unearthed a regulatory network driven by an HSA21 gene, which leads to genome-wide expression changes.
CONCLUSION
The findings from this study offer significant insights into the molecular alterations that occur in DS, shedding light on the pathological processes underlying this disorder. These results can potentially guide future research and treatment development for DS.
Topics: Humans; Mice; Animals; Down Syndrome; Mammals
PubMed: 37461266
DOI: 10.1002/ctm2.1310 -
Disease Models & Mechanisms Sep 2011Down syndrome (DS) is caused by trisomy of human chromosome 21 (Hsa21) and results in a large number of phenotypes, including learning difficulties, cardiac defects,... (Review)
Review
Down syndrome (DS) is caused by trisomy of human chromosome 21 (Hsa21) and results in a large number of phenotypes, including learning difficulties, cardiac defects, distinguishing facial features and leukaemia. These are likely to result from an increased dosage of one or more of the ∼310 genes present on Hsa21. The identification of these dosage-sensitive genes has become a major focus in DS research because it is essential for a full understanding of the molecular mechanisms underlying pathology, and might eventually lead to more effective therapy. The search for these dosage-sensitive genes is being carried out using both human and mouse genetics. Studies of humans with partial trisomy of Hsa21 have identified regions of this chromosome that contribute to different phenotypes. In addition, novel engineered mouse models are being used to map the location of dosage-sensitive genes, which, in a few cases, has led to the identification of individual genes that are causative for certain phenotypes. These studies have revealed a complex genetic interplay, showing that the diverse DS phenotypes are likely to be caused by increased copies of many genes, with individual genes contributing in different proportions to the variance in different aspects of the pathology.
Topics: Brain; Down Syndrome; Humans; Memory; Motor Activity
PubMed: 21878459
DOI: 10.1242/dmm.008078 -
Developmental Neuroscience 2011Down syndrome (DS) is the phenotypic consequence of trisomy 21 and is the most common genetically defined cause of intellectual disability. The most complete, widely... (Review)
Review
Down syndrome (DS) is the phenotypic consequence of trisomy 21 and is the most common genetically defined cause of intellectual disability. The most complete, widely available, and well-studied animal model of DS is the Ts65Dn mouse. Recent preclinical successes in rescuing learning and memory deficits in Ts65Dn mice are legitimate causes for optimism that pharmacotherapies for cognitive deficits in DS might be within reach. This article provides a snapshot of potential pharmacotherapies for DS, with emphasis on our recent results showing that the N-methyl-D-aspartate receptor antagonist memantine can reverse learning and memory deficits in Ts65Dn mice. Because memantine has already been approved for the therapy of Alzheimer's dementia, we have been able to very rapidly translate these results into human research and are currently conducting a 16-week, randomized, double-blind, placebo-controlled evaluation of the efficacy, tolerability and safety of memantine hydrochloride on enhancing the cognitive abilities of young adults with DS. The design and current status of this clinical trial will be discussed, which will be followed by some speculation on the potential impact of this and future clinical trials in the field of DS.
Topics: Animals; Cognition Disorders; Disease Models, Animal; Down Syndrome; Excitatory Amino Acid Antagonists; Humans; Memantine; Nerve Degeneration; Randomized Controlled Trials as Topic; Translational Research, Biomedical
PubMed: 21893967
DOI: 10.1159/000330861 -
Journal of Pediatric Endocrinology &... Jul 2020Objectives Limited data on the evolution of thyroid disorders (TD) in Down syndrome (DS) are available. We characterized the timing, prevalence, and dynamics of TD in...
Objectives Limited data on the evolution of thyroid disorders (TD) in Down syndrome (DS) are available. We characterized the timing, prevalence, and dynamics of TD in patients with DS during a long-term follow-up. Methods We retrospectively evaluated 91 children and adolescents with DS (12.5 ± 8.3; follow-up 7.5 ± 6.2). Children were monitored at birth, 6, and 12 months of age and twice a year thereafter. Thyroid status and autoimmunity were periodically investigated. Results TD were detected in 73.6% of patients, in particular congenital hypothyroidism (CH), autoimmune thyroid diseases (ATD) and subclinical hypothyroidism (SH) were recorded in 16.4, 31.8, and 25.3%, respectively. CH was diagnosed at newborn screening in 86.7% of cases and in the first 6 months of life in the remaining 13.3%; the condition was persistent in 61.5% of patients. In more than 30% of CH cases, glandular hypoplasia was also revealed. In the ATD group, 63.1% of patients with Hashimoto's disease (HD, 82.6%) were treated with levothyroxine and subjects with Graves' Disease (GD, 17.4%) started therapy with methimazole. DS with SH were treated in 42.1% of cases. A thyroid hypogenic echopattern, without autoantibody positivity was identified in 27.6% of SH patients. Conclusions The high prevalence and evolution of TD in SD requires frequent monitoring starting in the first months of life. CH can be misdiagnosed at screening. In DS subjects, there is a high prevalence of ATD and non-autoimmune diseases with early antibody-negative phases should not be excluded.
Topics: Adolescent; Age of Onset; Child; Child, Preschool; Disease Progression; Down Syndrome; Female; Follow-Up Studies; Humans; Infant; Infant, Newborn; Male; Prevalence; Prognosis; Retrospective Studies; Thyroid Diseases; Time Factors; Young Adult
PubMed: 32653879
DOI: 10.1515/jpem-2020-0119 -
TheScientificWorldJournal Feb 2007During preoperative evaluation for anesthesia in the Down patient, it is important to focus attention on the functional conditions of the patient and systems that... (Review)
Review
During preoperative evaluation for anesthesia in the Down patient, it is important to focus attention on the functional conditions of the patient and systems that frequently show anomalies. One of the challenges of evaluating pre-operative conditions and potential risks in the Down patient is the lack of a gold-standard evaluation score; cervical spine abnormalities, reduced dimensions and malformations of the airways, neurological changes, respiratory and cardiac disease, as well as endocrinological and metabolic alterations. We suggest, as a possible method of evaluation for patients with mental retardation and possible malformations, a new scale which takes the functional and mental conditions into account: the Sensorial, Psychological, Anatomical, Biological, Operational and Surgical (SPABOS) Compliance Score.
Topics: Anesthesia, General; Child; Cognition Disorders; Down Syndrome; Health Status Indicators; Humans; Perioperative Care; Preoperative Care; Prognosis; Risk Assessment; Risk Factors
PubMed: 17334615
DOI: 10.1100/tsw.2007.64 -
Journal of Intellectual Disability... Dec 2021Individuals with Down syndrome (DS) are at high risk for dementia, specifically Alzheimer's disease. However, many measures regularly used for the detection of dementia...
BACKGROUND
Individuals with Down syndrome (DS) are at high risk for dementia, specifically Alzheimer's disease. However, many measures regularly used for the detection of dementia in the general population are not suitable for individuals with DS due in part to floor effects. Some measures, including the Severe Impairment Battery (SIB), Brief Praxis Test (BPT) and Dementia Scale for People with Learning Disabilities (DLD), have been used in clinical trials and other research with this population. Validity research is limited, particularly regarding the use of such tools for detection of prodromal dementia in the DS population. The current project presents baseline cross-sectional SIB, BPT and DLD performance in order to characterise their predictive utility in discriminating normal cognition, possible dementia and probable dementia in adult DS.
METHOD
Baseline SIB, BPT and DLD performances from 100 individuals (no dementia = 68, possible dementia = 16 & probable dementia = 16) were examined from a longitudinal cohort of aging individuals with DS. Receiver operating characteristic curves investigated the accuracy of these measures in relation to consensus dementia diagnoses, diagnoses which demonstrated high percent agreement with the examining neurologist's independent diagnostic impression.
RESULTS
The SIB and BPT exhibited fair discrimination ability for differentiating no/possible versus probable dementia [area under the curve (AUC) = 0.61 and 0.66, respectively]. The DLD exhibited good discrimination ability for differentiating no versus possible/probable dementia (AUC = 0.75) and further demonstrated better performance of the DLD Cognitive subscale compared with the DLD Social subscale (AUC = 0.77 and 0.67, respectively).
CONCLUSIONS
Results suggest that the SIB, BPT and DLD are able to reasonably discriminate consensus dementia diagnoses in individuals with DS, supporting their continued use in the clinical assessment of dementia in DS. The general performance of these measures suggests that further work in the area of test development is needed to improve on the AUCs for dementia status discrimination in this unique population. At present, however, the current findings suggest that the DLD may be the best option for reliable identification of prodromal dementia in this population, reinforcing the importance of including informant behaviour ratings in assessment of cognition for adults with DS.
Topics: Adult; Alzheimer Disease; Cross-Sectional Studies; Dementia; Down Syndrome; Humans; Learning Disabilities; Neuropsychological Tests
PubMed: 34786786
DOI: 10.1111/jir.12901 -
Human Pathology Dec 1991Down syndrome (DS) is not usually thought of in association with significant infantile liver disease. We present clinical and histopathologic data from 10 patients with... (Review)
Review
Down syndrome (DS) is not usually thought of in association with significant infantile liver disease. We present clinical and histopathologic data from 10 patients with DS who presented with severe liver disease at birth or within the first few weeks of life, and summarize the findings of eight previously reported cases. The liver disease was fatal in all but one case. Diffuse lobular fibrosis surrounding proliferating ductular elements and residual hepatocytes characterized the pathologic findings in the liver in all patients. A large number of megakaryocytes were present in the liver in nine of 12 patients. The phenotype of "perinatal hemochromatosis" was documented in eight of nine cases in which the presence of iron was investigated. Since only a fraction of the patients with this phenotype have DS, the patients we describe seem to represent a relatively well-defined subset of the perinatal hemochromatosis phenotype. The existence of such a subset suggests that the perinatal hemochromatosis phenotype does not represent a single etiopathogenetic disorder. The association between DS, megakaryocytic infiltrates in the liver, and fatal subacute/chronic liver disease gives rise to the speculation that fibrosis-promoting factors and/or metabolic abnormalities, such as those resulting from a gene dosage effect, may play a role in the genesis of the liver disease, perhaps due to a particular susceptibility of fetal liver.
Topics: Down Syndrome; Female; Humans; Infant, Newborn; Liver Diseases; Male
PubMed: 1836197
DOI: 10.1016/0046-8177(91)90111-2 -
Journal of Genetics 2021Congenital heart defects (CHD) affect 50% of Down's syndrome (DS) cases. This review focusses on the pathogenic molecular mechanism leading to the formation of... (Review)
Review
Congenital heart defects (CHD) affect 50% of Down's syndrome (DS) cases. This review focusses on the pathogenic molecular mechanism leading to the formation of DS-associated CHD along with the advancement of the emerging diagnostic techniques available for such patients in past few decades. We have shed light on the causative genes of DS-associated CHD that are located either on chromosome 21 or outside chromosome 21. Along with locus-specific mutation, numerous SNP and CNV, miRNA, use of maternal folic acid during pregnancy and signalling pathways are also reported to contribute to the formation of CHD in patients with DS. With the help of both these our understanding of pathogenic mechanism causing CHD in DS cases along with the availability of emerging technologies has facilitated a novel discovery that has ultimately provided a better treatment and management for such cases. Accurate diagnosis and treatment are now available with the introduction of CNV detection and NGS based approaches such as WES, WGS, target sequencing and sequencing of foetal cell-free DNA by the medical geneticist and cardiologist have now allowed further identification of familial recurrence risk and relatives who are at risk through genetic counselling, thereby providing reproductive options and improving proper care of DS-associated CHD. Further, gene-editing studies explore novel pathogenic mechanisms and signalling pathways in DS-associated CHD.
Topics: Down Syndrome; Female; Folic Acid; Genetic Counseling; Heart Defects, Congenital; Humans; MicroRNAs; Pregnancy
PubMed: 34282736
DOI: No ID Found -
Down's Syndrome, Research and Practice... Oct 2008Folate is an important vitamin that contributes to cell division and growth and is therefore of particular importance during infancy and pregnancy. Folate deficiency has... (Review)
Review
Folate is an important vitamin that contributes to cell division and growth and is therefore of particular importance during infancy and pregnancy. Folate deficiency has been associated with slowed growth, anaemia, weight loss, digestive disorders and some behavioural issues. Adequate folate intake around the time of conception and early pregnancy can reduce the risk of certain problems including neural tube defects. It has been suggested that certain versions (polymorphisms) of some genes can increase the risk of conceiving a baby with Down syndrome. If this is the case, then people with Down syndrome may be more likely to carry these forms of these genes and to experience associated problems in folate metabolism. Studies to date have found conflicting results, suggesting that these gene variants may be part of a more complex picture. In this issue, a further study reports no association between the presence of a common polymorphism of one of these genes and the risk of having a child with Down syndrome among mothers of Northern Indian origin. This article reviews these challenging findings and looks at where investigations can now go to resolve these issues.
Topics: Down Syndrome; Folic Acid; Humans; Methylenetetrahydrofolate Reductase (NADPH2); Polymorphism, Genetic; Risk; Vitamins
PubMed: 19026278
DOI: 10.3104/updates.2051