Alzheimer's disease and its complications are the leading cause of death in adults with Down syndrome. Studies have assessed Alzheimer's disease in individuals with Down syndrome, but the natural ...history of biomarker changes in Down syndrome has not been established. We characterised the order and timing of changes in biomarkers of Alzheimer's disease in a population of adults with Down syndrome.
We did a dual-centre cross-sectional study of adults with Down syndrome recruited through a population-based health plan in Barcelona (Spain) and through services for people with intellectual disabilities in Cambridge (UK). Cognitive impairment in participants with Down syndrome was classified with the Cambridge Cognitive Examination for Older Adults with Down Syndrome (CAMCOG-DS). Only participants with mild or moderate disability were included who had at least one of the following Alzheimer's disease measures: apolipoprotein E allele carrier status; plasma concentrations of amyloid β peptides 1–42 and 1–40 and their ratio (Aβ1–42/1–40), total tau protein, and neurofilament light chain (NFL); tau phosphorylated at threonine 181 (p-tau), and NFL in cerebrospinal fluid (CSF); and one or more of PET with 18F-fluorodeoxyglucose, PET with amyloid tracers, and MRI. Cognitively healthy euploid controls aged up to 75 years who had no biomarker abnormalities were recruited from the Sant Pau Initiative on Neurodegeneration. We used a first-order locally estimated scatterplot smoothing curve to determine the order and age at onset of the biomarker changes, and the lowest ages at the divergence with 95% CIs are also reported where appropriate.
Between Feb 1, 2013, and June 28, 2019 (Barcelona), and between June 1, 2009, and Dec 31, 2014 (Cambridge), we included 388 participants with Down syndrome (257 66% asymptomatic, 48 12% with prodromal Alzheimer's disease, and 83 21% with Alzheimer's disease dementia) and 242 euploid controls. CSF Aβ1–42/1–40 and plasma NFL values changed in individuals with Down syndrome as early as the third decade of life, and amyloid PET uptake changed in the fourth decade. 18F-fluorodeoxyglucose PET and CSF p-tau changes occurred later in the fourth decade of life, followed by hippocampal atrophy and changes in cognition in the fifth decade of life. Prodromal Alzheimer's disease was diagnosed at a median age of 50·2 years (IQR 47·5–54·1), and Alzheimer's disease dementia at 53·7 years (49·5–57·2). Symptomatic Alzheimer's disease prevalence increased with age in individuals with Down syndrome, reaching 90–100% in the seventh decade of life.
Alzheimer's disease in individuals with Down syndrome has a long preclinical phase in which biomarkers follow a predictable order of changes over more than two decades. The similarities with sporadic and autosomal dominant Alzheimer's disease and the prevalence of Down syndrome make this population a suitable target for Alzheimer's disease preventive treatments.
Instituto de Salud Carlos III, Fundació Bancaria La Caixa, Fundació La Marató de TV3, Medical Research Council, and National Institutes of Health.
Research to guide clinicians in the management of the devastating regression which can affect adolescents and young adults with Down syndrome is limited. A multi‐site, international, longitudinal ...cohort of individuals with a clinical diagnosis of Unexplained Regression in Down syndrome (URDS) was collated through seven Down syndrome clinics. Tiered medical evaluation, a 28‐item core symptom list, and interim management are described naturalistically. Improvement—defined by the percentage of baseline function on a Parent‐reported Functional Score, overall improvement in symptoms on a Clinician‐administered Functional Assessment, or report of management type being associated with improvement—was analyzed. Improvement rates using ECT, IVIG, and others were compared. Across seven clinics, 51 patients with URDS had regression at age 17.6 years, on average, and showed an average 14.1 out of 28 symptoms. Longitudinal improvement in function was achieved in many patients and the medical management, types of treatment, and their impact on function are described. Management with intravenous immunoglobulin (IVIG) was significantly associated with higher rate of improvement in symptoms at the next visit (p = 0.001). Our longitudinal data demonstrates that URDS is treatable, with various forms of clinical management and has a variable course. The data suggests that IVIG may be an effective treatment in some individuals. Our description of the management approaches used in this cohort lays the groundwork for future research, such as development of standardized objective outcome measure and creation of a clinical practice guideline for URDS.
Increased cerebrospinal fluid neurofilament light (NfL) is a recognized biomarker for neurodegeneration that can also be assessed in blood. Here, we investigate plasma NfL as a marker of ...neurodegeneration in 13 neurodegenerative disorders, Down syndrome, depression and cognitively unimpaired controls from two multicenter cohorts: King's College London (n = 805) and the Swedish BioFINDER study (n = 1,464). Plasma NfL was significantly increased in all cortical neurodegenerative disorders, amyotrophic lateral sclerosis and atypical parkinsonian disorders. We demonstrate that plasma NfL is clinically useful in identifying atypical parkinsonian disorders in patients with parkinsonism, dementia in individuals with Down syndrome, dementia among psychiatric disorders, and frontotemporal dementia in patients with cognitive impairment. Data-driven cut-offs highlighted the fundamental importance of age-related clinical cut-offs for disorders with a younger age of onset. Finally, plasma NfL performs best when applied to indicate no underlying neurodegeneration, with low false positives, in all age-related cut-offs.
Haematopoiesis in the bone marrow (BM) maintains blood and immune cell production throughout postnatal life. Haematopoiesis first emerges in human BM at 11-12 weeks after conception
, yet almost ...nothing is known about how fetal BM (FBM) evolves to meet the highly specialized needs of the fetus and newborn. Here we detail the development of FBM, including stroma, using multi-omic assessment of mRNA and multiplexed protein epitope expression. We find that the full blood and immune cell repertoire is established in FBM in a short time window of 6-7 weeks early in the second trimester. FBM promotes rapid and extensive diversification of myeloid cells, with granulocytes, eosinophils and dendritic cell subsets emerging for the first time. The substantial expansion of B lymphocytes in FBM contrasts with fetal liver at the same gestational age. Haematopoietic progenitors from fetal liver, FBM and cord blood exhibit transcriptional and functional differences that contribute to tissue-specific identity and cellular diversification. Endothelial cell types form distinct vascular structures that we show are regionally compartmentalized within FBM. Finally, we reveal selective disruption of B lymphocyte, erythroid and myeloid development owing to a cell-intrinsic differentiation bias as well as extrinsic regulation through an altered microenvironment in Down syndrome (trisomy 21).
Overexpression of the amyloid precursor protein (APP) gene on chromosome 21 in Down syndrome (DS) has been linked to increased brain amyloid levels and early-onset Alzheimer's disease (AD). An ...elderly man with phenotypic DS and partial trisomy of chromosome 21 (PT21) lacked triplication of APP affording an opportunity to study the role of this gene in the pathogenesis of dementia. Multidisciplinary studies between ages 66-72 years comprised neuropsychological testing, independent neurological exams, amyloid PET imaging with 11C-Pittsburgh compound-B (PiB), plasma amyloid-β (Aβ) measurements, and a brain autopsy examination. The clinical phenotype was typical for DS and his intellectual disability was mild in severity. His serial neuropsychological test scores showed less than a 3% decline as compared to high functioning individuals with DS who developed dementia wherein the scores declined 17-28% per year. No dementia was detected on neurological examinations. On PiB-PET scans, the patient with PT21 had lower PiB standard uptake values than controls with typical DS or sporadic AD. Plasma Aβ42 was lower than values for demented or non-demented adults with DS. Neuropathological findings showed only a single neuritic plaque and neurofibrillary degeneration consistent with normal aging but not AD. Taken together the findings in this rare patient with PT21 confirm the obligatory role of APP in the clinical, biochemical, and neuropathological findings of AD in DS.
Noninvasive prenatal screening (NIPS) using cell-free DNA has transformed prenatal care. Belgium was the first country to implement and fully reimburse NIPS as a first-tier screening test offered to ...all pregnant women. A consortium consisting of all Belgian genetic centers report the outcome of two years genome-wide NIPS implementation.
The performance for the common trisomies and for secondary findings was evaluated based on 153,575 genome-wide NIP tests. Furthermore, the evolution of the number of invasive tests and the incidence of Down syndrome live births was registered.
Trisomies 21, 18, and 13 were detected in respectively 0.32%, 0.07%, and 0.06% of cases, with overall positive predictive values (PPVs) of 92.4%, 84.6%, and 43.9%. Rare autosomal trisomies and fetal segmental imbalances were detected in respectively 0.23% and 0.07% of cases with PPVs of 4.1% and 47%. The number of invasive obstetric procedures decreased by 52%. The number of trisomy 21 live births dropped to 0.04%.
Expanding the scope of NIPS beyond trisomy 21 fetal screening allows the implementation of personalized genomic medicine for the obstetric population. This genome-wide NIPS approach has been embedded successfully in prenatal genetic care in Belgium and might serve as a framework for other countries offering NIPS.
We aimed to estimate the nonselective live birth prevalence, actual live birth prevalence, reduction percentage because of selective terminations, and population prevalence for Down syndrome (DS) in ...European countries. The number of people with DS alive in a country was estimated by first modeling the number of live births of children with DS by year of birth. Subsequently, for these different years of birth, survival curves for people with DS were constructed and then applied to these yearly estimates of live births with DS. For Europe, 2011-2015, we estimate 8,031 annual live births of children with DS, which would have been around 17,331 births annually, absent selective terminations. The estimated reduction of live birth prevalence was, on average, 54%, varying between 0% in Malta and 83% in Spain. As of 2015, we estimate 417,000 people with DS are living in Europe; without elective terminations, there would have been about 572,000 people with DS, which corresponds to a population reduction rate of 27%. Such statistics can be important barometers for prenatal testing trends and resource allocation within countries. Disability awareness initiatives and public policy initiatives can also be better grounded with these more precise estimates.
Down syndrome (DS) is a genetic disease characterized by a supernumerary chromosome 21. Intellectual deficiency (ID) is one of the most prominent features of DS. Central nervous system defects lead ...to learning disabilities, motor and language delays, and memory impairments. At present, a prenatal treatment for the ID in DS is lacking. Subcutaneous administration of synthetic preimplantation factor (sPIF, a peptide with a range of biological functions) in a model of severe brain damage has shown neuroprotective and anti-inflammatory properties by directly targeting neurons and microglia. Here, we evaluated the effect of PIF administration during gestation and until weaning on Dp(16)1Yey mice (a mouse model of DS). Possible effects at the juvenile stage were assessed using behavioral tests and molecular and histological analyses of the brain. To test the influence of perinatal sPIF treatment at the adult stage, hippocampus-dependent memory was evaluated on postnatal day 90. Dp(16)1Yey pups showed significant behavioral impairment, with impaired neurogenesis, microglial cell activation and a low microglial cell count, and the deregulated expression of genes linked to neuroinflammation and cell cycle regulation. Treatment with sPIF restored early postnatal hippocampal neurogenesis, with beneficial effects on astrocytes, microglia, inflammation, and cell cycle markers. Moreover, treatment with sPIF restored the level of DYRK1A, a protein that is involved in cognitive impairments in DS. In line with the beneficial effects on neurogenesis, perinatal treatment with sPIF was associated with an improvement in working memory in adult Dp(16)1Yey mice. Perinatal treatment with sPIF might be an option for mitigating cognitive impairments in people with DS.
Individuals with Down syndrome (DS) have specific health care needs and require additional screening and surveillance for commonly associated conditions. The American Academy of Pediatrics (AAP) ...Committee on Genetics has provided clinical guidance in “Health Supervision for Children and Adolescents with Down Syndrome.” Many DS specialty centers (DSC) have been created, in part, to help ensure adherence to these guidelines. The primary purpose of this work is to determine the financial impact of a specialized DSC. A retrospective chart review was completed for all patients seen in DSC for fiscal year 2018 (June 2018–June 2019). Charts were reviewed to ascertain the financial impact of a DSC to a healthcare system by calculating total downstream charges (using CMS Chargemaster) as a surrogate marker for financial impact. Five‐hundred‐seventy‐four patient encounters were conducted; 99 were new patient visits. Annual charges totaled $1,399,450. The 1–5‐year‐old age group accounted for greater than half of all charges. The greatest proportion of charges resulted from sleep studies and other diagnostic testing (55%). DS clinics are extremely helpful in ensuring that children receive guideline‐based care. Taking into account downstream revenue, specialized DSCs are also financially beneficial to the institutions with whom they are affiliated.
PDF
