Population prevalence of Down's syndrome in the United Kingdom

Editorial on common mental health disorders and cognitive decline in a longitudinal Down syndrome cohort

This editorial discusses a study by Idris and colleagues, where the authors investigated the impact of common mental disorders (CMDs) among patients with Down syndrome, with respect to development of clinical features of Alzheimer's disease.

Adaptation at the Family Level in Families of Individuals With Down Syndrome: A Scoping Review

Down syndrome (DS) is a chromosomal disorder associated with intellectual and physical disabilities and has historically been viewed by health care providers through a negative lens when considering the effect the condition has on the individual, family, and community. The purpose of this scoping review was to provide an overview of recent research concerning adaptation in families of individuals with DS with a focus on family adaptation rather than individual or dyadic adaptation. Three literature indexes were searched from 2017 to 2022, with 41 articles included. Foci of the studies included strength/resilience, stress/coping, and negative/challenge. Thirteen studies reported using a family framework. Multiple methodological approaches and family measures were used in the studies and are outlined. Findings from this review show there has been a shift in focus when researching families of individuals with DS from a negative and challenging experience to one of strength and resilience.

An approach to identifying young children with developmental disabilities via primary care records

Background: Preschool aged children with developmental disabilities frequently receive a diagnosis of an indicator of disability, such as developmental delay, some time before receiving a definitive diagnosis at school age, such as autism spectrum disorder. The absence of a definitive diagnosis potentially underestimates the need for support by families with young disabled children, also delaying the access of families to condition-specific information and support. Our aim was to develop a strategy to identify children with probable and potential developmental disabilities before the age of five in primary care records for a UK birth cohort, considering how the identification of only probable or potential developmental disability might influence prevalence estimates.

Methods: As part of a study of the effects of caring for young children with developmental disabilities on mothers’ health and healthcare use, we developed a two-part strategy to identify: 1) children with conditions associated with significant disability and which can be diagnosed during the preschool period; and 2) children with diagnoses which could indicate potential disability, such as motor development disorder. The strategy, using Read codes, searched the electronic records of children in the Born in Bradford cohort with linked maternal and child sociodemographic information. The results were compared with national and Bradford prevalence estimates.

Results: We identified 83 children with disability conditions and 394 with potential disability (44 children had a disability condition and an indicator of potential disability). Combined they produced a developmental disability prevalence of 490 per 10,000 which is above the UK estimate for developmental disabilities in children under five (468 per 10,000) and within the 419-505 per 10,000 prevalence estimated for Bradford (for children aged 0-18).

Conclusions: When disability prevalence is estimated only using conditions diagnosed as developmental disabilities, most young children with developmental disabilities likely to be diagnosed at later ages will be missed.

One-carbon metabolism and global DNA methylation in mothers of individuals with Down syndrome

Down syndrome (DS) is the most common chromosomal disorder, resulting from the failure of normal chromosome 21 segregation. Studies have suggested that impairments within the one-carbon metabolic pathway can be of relevance for the global genome instability observed in mothers of individuals with DS. Based on the association between global DNA hypomethylation, genome instability, and impairments within the one-carbon metabolic pathway, the present study aimed to identify possible predictors, within the one-carbon metabolism, of global DNA methylation, measured by methylation patterns of LINE-1 and Alu repetitive sequences, in mothers of individuals with DS and mothers of individuals without the syndrome. In addition, we investigated one-carbon genetic polymorphisms and metabolites as maternal predisposing factors for the occurrence of trisomy 21 in children. Eighty-three samples of mothers of children with DS with karyotypically confirmed free trisomy 21 (case group) and 84 of mothers who had at least one child without DS or any other aneuploidy were included in the study. Pyrosequencing assays were performed to access global methylation. The results showed that group affiliation (case or control), betaine-homocysteine methyltransferase (BHMT) G742A and transcobalamin 2 (TCN2) C776G polymorphisms, and folate concentration were identified as predictors of global Alu DNA methylation values. In addition, thymidylate synthase (TYMS) 28-bp repeats 2R/3R or 3R/3R genotypes are independent maternal predisposing factors for having a child with DS. This study adds evidence that supports the association of impairments in the one-carbon metabolism, global DNA methylation, and the possibility of having a child with DS.

Epidemiology of Acute Leukemia among Children with Down Syndrome in Korea

Purpose

Children with Down syndrome (DS) show a higher risk of acute leukemia than those without DS. In this study, we investigated the nationwide incidence of acute leukemia among children with DS and compared their epidemiologic characteristics with those of children with acute leukemia but without DS.

Materials and Methods

Using the National Health Insurance Service database, we selected patients with acute leukemia aged 0–19 years at diagnosis between 2007 and 2016.

Results

Among the 4,697 children with acute leukemia, 54 (1.1%) had DS. The median incidence rate of leukemia with DS by year was 1.3% (range, 0.2% to 2.0%). Sixteen patients with acute lymphoblastic leukemia (ALL; 29.6%) and 36 with acute myeloid leukemia (AML; 66.7%) had DS. The DS group showed younger age at diagnosis than the non-DS group, and diagnosis of AML was more frequent in the DS group than in the non-DS group (3 years vs. 9 years, p < 0.001; 66.7% vs. 32.4%, p < 0.001, respectively). The 5-year overall survival was comparable between the DS and non-DS groups (88.0% vs. 81.9%, p=0.375). Among all the Koreans born between 2007 and 2008, the incidences of acute leukemia, ALL, and AML were 49.25, 20.75, and 163.38 times higher, respectively, in the DS group than in the non-DS group.

Conclusion

Our findings support the fact that the incidence of acute leukemia is higher among patients with DS than among those without DS in Korea. However, the DS and non-DS groups in this study had a comparable overall survival rate.

Multi-segmental postural control patterns in down syndrome

BACKGROUND

Patients with Down Syndrome (DS) exhibit less efficient and unstable standing postural control. The specificities of somatosensorial deficits might result in a different utilization of resources and in distinct whole-body kinematic patterns, to date still unexplored. In this paper we aim at addressing multi-segmental coordination patterns in people with DS while maintaining standing balance under different visual conditions (open and closed eyes).

METHODS

This cross-sectional observational cohort study involved two groups of 23 patients with DS and 12 healthy controls. A 30-s standing balance test allowed to extract (i) the length of the trajectory of the center-of-pressure sway and 95% confidence ellipse area from Ground Reaction forces, and (ii) Principal Movement (PM) components from full-body motion kinematics; the latter were obtained exploiting a Principal Component Analysis-based approach, also embracing a motor-control perspective through the evaluation of the number of modifications applied by the neuromuscular controller on segments' acceleration.

FINDINGS

Trajectory length was significantly higher in patients; 95% ellipse confidence area did not differ between groups/condition. Postural movement components differed in people with DS from healthy controls not only in the "observable", behavioural phenotype (PM3 and PM8), but also in the amount of activation of the associated control (PM1 to PM8, over-activated in DS) in all spatial directions.

INTERPRETATION

Results reinforced the prevalence of a medio-lateral hip strategy (instead of an ankle strategy) in maintaining postural stability. Most important, they revealed a less frequent activation of postural patterns in all spatial directions.

Effect of antibiotics in preventing hospitalizations from respiratory tract infections in children with Down syndrome

BACKGROUND

Children with Down syndrome (DS) are at high risk of respiratory tract infections (RTIs) due to anatomical variations, comorbidities, and immune system immaturity. Evidence on interventions to reduce this risk is incomplete. This study aims to quantify the effect of antibiotics prescribed for RTIs in primary care on the subsequent risk of RTI-related hospitalization for children with DS versus controls.

METHODS

We conducted a retrospective cohort study of 992 children with DS and 4874 controls managed by UK National Health Service General Practitioners (GPs) and hospitals as identified in CALIBER (Clinical disease research using LInked Bespoke studies and Electronic health Records), 1997-2010. Univariate and multivariate logistic regression were undertaken.

RESULTS

In children with DS, the prescription of antibiotics following an RTI-related GP consultation did not significantly reduce the risk of RTI-related hospitalization in the subsequent 28 days (risk with antibiotics, 1.8%; without, 2.5%; risk ratio, 0.699; 95% confidence interval, 0.471-1.036). Subgroup analyses showed a risk reduction only in infants with DS, after adjustment for covariates. There was no reduction in risk for controls, overall or across subgroups.

CONCLUSIONS

In conclusion, while prescription of antibiotics following RTI-related GP consultations were effective for infants with DS in reducing subsequent RTI-related hospitalization, this was not the case for older children with DS. We would encourage further high-quality cohort and randomized controlled trials to interrogate this finding, and to examine the impact of antibiotics on other endpoints, including symptom duration.

Estimation of the number of people with Down syndrome in Europe

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.

Adults with Down syndrome challenge another paradigm: When aging no longer entails arterial hypertension

The paradigmatic relationship between aging and atherosclerotic cardiovascular events does not apply to all patient populations. Though trisomy 21 (T21) and its phenotypic expression, Down syndrome (DS), are conditions that involve premature aging, the cardiovascular system of adults with DS appears to be particularly spared from this early senescence. Despite a higher prevalence of some classic cardiovascular risk factors in adults with DS than in the general population, such as dyslipidemia, obesity, or sedentarism, these individuals do not develop hypertension or suffer major cardiovascular events as they age. The protective factors that prevent the development of hypertension in T21 are not well established. Genes like RCAN1 and DYRK1A, both on chromosome 21 and over-expressed in adults with DS, appear to play a major role in cardiovascular prevention. Their regulation of the renin-angiotensin-aldosterone system (RAAS) and neprilysin synthesis could underlie the constitutive protection against arterial hypertension in adults with DS and explain the absence of increased arterial stiffness in this population. A better understanding of these molecular pathways could have enormous implications for the clinical management of adults with DS and might foster the development of novel therapeutic targets in cardiovascular prevention for the general population.

The Population Prevalence, Associations of Congenital Heart Defect and Mortality Risk for Down's Syndrome in South Korea Based on National Health Insurance Service (NHIS) Data

Background

In the present study, we estimated the population prevalence, associations of congenital heart defect (CHD) and mortality risk for DS using data from National Health Insurance Service (NHIS) and Rare Diseases Registry (RDR).

Methods

We collected data on subjects with DS who were registered in the RDR between 2010 and 2015. To estimate associations of CHD and mortality risk of DS, the data of DS subjects were compared with 1:5 age- and sex-matched controls.

Results

In 2015, 2077 individuals with DS were identified out of the total population of 51,574,044 South Koreans and the prevalence was 4.03 per 100,000 persons. The trend of DS population prevalence across 10-year-old intervals showed a peak in the group under the age of 10 years (26.0 per 100,000 persons) and then declined sharply after the age of 20 years (0.98 per 100,000 persons at 30-39 years of age). In subjects with DS, the frequencies of atrial septal defect [odds ratios (OR) =65.9; 95% CI, 84.1-99.1], ventricular septal defect (OR = 88.1, 95% CI, 57.9-134.1), patent ductus arteriosus (OR = 56.9, 95% CI, 40.1-80.8), tetralogy of fallot (OR = 42.1, 95% CI, 19.3-92.3), or atrioventricular septal defect (OR = 510.0, 95% CI, 126.7-999.0) were higher than those of age- and sex-matched controls. The risk of death in patients with DS was significantly higher than that of age- and sex-matched controls [hazard ratio (HR) =41.7, 95% CI 20.0-87.0].

Conclusion

In South Korea, the DS population prevalence was 4.03 per 100,000 persons in 2015. The subjects with DS were more likely to accompany CHD and have higher mortality risk than healthy controls.

Nocturnal hypoventilation in Down syndrome children with or without sleep apnea

BACKGROUND

There is a high prevalence of obstructive sleep apnea (OSA) in children with Down syndrome (DS), sometimes associated with alveolar hypoventilation.

OBJECTIVE

To compare transcutaneous partial pressure of carbon dioxide (PtcCO₂ ) and pulse oximetry (SpO₂ ) in children with DS and in control children with OSA.

PATIENTS AND METHODS

This retrospective case-control study involved children followed in Trousseau Hospital (Paris) Sleep Center. Polysomnography (PSG) recordings and clinical files of children with DS were reviewed to identify clinical signs of OSA and comorbidities associated with DS. Controls were children who presented with OSA of ENT origin without other comorbidities (exceptions: two overweight, one obese, and three with well-controlled asthma). DS subjects and controls were matched for age and apnea hypopnea index.

RESULTS

There were 28 children in each group. Mean PtcCO₂ during sleep was significantly higher in patients with DS compared to controls (44 mm Hg vs 42 mm Hg, P = .001). Five (21%) patients with DS met the American Academy of Sleep medicine criteria for hypoventilation, compared to one (4%) in the control group. The mean PtcO₂ during sleep was significantly lower in patients with DS (77 mm Hg vs 82 mm Hg, P = .003).

CONCLUSIONS

This is the first study to compare nocturnal gas exchange in children with DS to a control group of children with similar OSA. Our data demonstrate that children with DS have increased PtcCO₂ regardless of the presence of OSA and its severity. This may be due to respiratory muscle hypotonia and/or ventilatory control alteration in patients with DS.

The Underreporting of Vision Problems in Statutory Documents of Children with Williams Syndrome and Down Syndrome

Vision problems can lead to negative developmental outcomes. Children with Williams syndrome and Down syndrome are at higher risk of vision problems, and these are less likely to be detected due to diagnostic overshadowing and difficulty accessing eye-care. Education, Health and Care (EHC) plans are statutory documents, introduced by the Children and Families Act 2014 in England, with the intention of integrating provision across these domains. Vision issues should be reported in these plans, and recommendations made about appropriate adjustments for them. We analysed the EHC plans from 53 children with Down or Williams syndrome. Our results showed significant underreporting, especially for children with Williams syndrome, and little explanation of what adjustments should be made. We also report pockets of good practice.

Clinical performance of non-invasive prenatal testing for trisomies 21, 18 and 13 in twin pregnancies: A cohort study and a systematic meta-analysis

INTRODUCTION

The objective of this study was to report on the clinical performance of non-invasive prenatal testing (NIPT) for trisomies 21, 18 and 13 in twin pregnancies and to define the performance of NIPT by combining our cohort study results with published studies in a systematic meta-analysis.

MATERIAL AND METHODS

A cohort study was carried out in the First Affiliated Hospital of Sun Yat-sen University and Kanghua Hospital. Meanwhile, searches of PubMed, EMBASE, The Cochrane Library and Web of Science for all relevant peer-reviewed articles were performed with a restriction to English language publication before 15 June 2019. Quality assessments were conducted with the Quality Assessment Tool for Diagnostic Accuracy Studies-2 checklist. Data analysis, heterogeneity, subgroup analysis and publication bias were carried out using META-DISC 1.4 and STATA 12.0.

RESULTS

In all, 141 twin pregnancies included in our cohort study; confirmation revealed one true-positive case for trisomy 21 and 140 true-negative cases. The sensitivity and specificity for trisomy 21 by NIPT were both 100%. Twenty-two eligible studies were enrolled in this meta-analysis together with our study. There were 199 cases of trisomy 21, 58 cases of trisomy 18, 14 cases of trisomy 13 and 6347 cases of euploids in total. For trisomy 21, NIPT showed the pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and diagnostic odds ratio were 0.99, 1.00, 145.81, 0.06 and 1714.09, respectively. For trisomy 18, the pooled sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and diagnostic odds ratio were 0.88, 1.00, 200.98, 0.19 and 483.68, respectively.

CONCLUSIONS

The performance of NIPT for trisomy 21 in twin pregnancy was excellent and it was similar to that reported in singleton pregnancy. However, due to publication bias (trisomy 18) and small number of cases (trisomy 13), accurate assessment of the predictive performance of NIPT for trisomies 18 and 13 could not be achieved.

Alzheimer's disease in Down syndrome: An overlooked population for prevention trials

The discovery that adults with Down syndrome (DS) have neuropathological features identical to individuals with sporadic Alzheimer's disease (AD) played a key role in the identification of the amyloid precursor protein gene on chromosome 21 and resulted in the amyloid cascade hypothesis. Individuals with DS have a lifetime risk for dementia in excess of 90%, and DS is now acknowledged to be a genetic form of AD similar to rare autosomal-dominant causes. Just as DS put the spotlight on amyloid precursor protein mutations, it is also likely to inform us of the impact of manipulating the amyloid pathway on treatment outcomes in AD. Ironically, however, individuals with DS are usually excluded from AD trials. This review will discuss primary and secondary prevention trials for AD in DS and the potential barriers and solutions to such trials and describe the Europe-wide Horizon21 Consortium to establish a DS-AD prevention clinical trials network.

Mosaic Turner syndrome shows reduced penetrance in an adult population study

Purpose

Many women with X chromosome aneuploidy undergo lifetime clinical monitoring for possible complications. However, ascertainment of cases in the clinic may mean that the penetrance has been overestimated.

Methods

We characterized the prevalence and phenotypic consequences of X chromosome aneuploidy in a population of 244,848 women over 40 years of age from UK Biobank, using single-nucleotide polymorphism (SNP) array data.

Results

We detected 30 women with 45,X; 186 with mosaic 45,X/46,XX; and 110 with 47,XXX. The prevalence of nonmosaic 45,X (12/100,000) and 47,XXX (45/100,000) was lower than expected, but was higher for mosaic 45,X/46,XX (76/100,000). The characteristics of women with 45,X were consistent with the characteristics of a clinically recognized Turner syndrome phenotype, including short stature and primary amenorrhea. In contrast, women with mosaic 45,X/46,XX were less short, had a normal reproductive lifespan and birth rate, and no reported cardiovascular complications. The phenotype of women with 47,XXX included taller stature (5.3 cm; SD = 5.52 cm; P = 5.8 × 10⁻²⁰) and earlier menopause age (5.12 years; SD = 5.1 years; P = 1.2 × 10⁻¹⁴).

Conclusion

Our results suggest that the clinical management of women with 45,X/46,XX mosaicism should be minimal, particularly those identified incidentally.

Chromosomal abnormalities: subgroup analysis by maternal age and perinatal features in zhejiang province of China, 2011-2015

BACKGROUND

Recently, the prevalence of chromosomal abnormalities (CA) increased as the increasing proportion of mothers with advanced age. We aimed to explore the prevalence of CA in relation to maternal age and perinatal features.

METHODS

A retrospective study was performed based on provincial birth defects surveillance data. The relative risk (RR) and 95% confidence interval (CI) were used to calculate maternal age-specific rates of CA. Socio-demographic characteristics of mothers and perinatal features were listed.

RESULTS

The total prevalence of CA was 6.38 per 10,000 births, which increased per 10,000 births linearly from 4.02 in 2011 to 9.13 in 2015 (x ²_line-trend =52.69, p < 0.001). During this period, the prevalence for CA per 10,000 births among women over 35 years old increased from 15.34 in 2011 to 33.82 in 2015 (x ²_line-trend =115121.6, p < 0.001). The RR for overall CA, trisomy 21(T21), trisomy 18(T18) and others in mothers 35 years or older were 6.64 (95% CI 5.55 ~ 7.93), 6.83 (95% CI 5.63 ~ 8.30), 4.06 (95% CI 2.09 ~ 7.90) and 7.54 (95% CI 4.02 ~ 14.11) respectively in comparison to mothers aged 25-29 years old. The stillbirths rate for total CA was 76.45%. T21 and T18 were strongly associated with multiple anomalies, especially congenital heart abnormalities.

CONCLUSIONS

The prevalence of CA increased as maternal age increased. Cases with CA were associated with other congenital defects and high mortality risk.