Epidemiology of Down syndrome in 118,265 consecutive births

Impact of increased APP gene dose in Down syndrome and the Dp16 mouse model

INTRODUCTION

People with Down syndrome (DS) are predisposed to Alzheimer's disease (AD). The amyloid hypothesis informs studies of AD. In AD-DS, but not sporadic AD, increased APP copy number is necessary, defining the APP gene dose hypothesis. Which amyloid precursor protein (APP) products contribute needs to be determined.

METHODS

Brain levels of full-length protein (fl-hAPP), C-terminal fragments (hCTFs), and amyloid beta (Aβ) peptides were measured in DS, AD-DS, non-demented controls (ND), and sporadic AD cases. The APP gene-dose hypothesis was evaluated in the Dp16 model.

RESULTS

DS and AD-DS differed from ND and AD for all APP products. In AD-DS, Aβ42 and Aβ40 levels exceeded AD. APP products were increased in the Dp16 model; increased APP gene dose was necessary for loss of vulnerable neurons, tau pathology, and activation of astrocytes and microglia.

DISCUSSION

Increases in APP products other than Aβ distinguished AD-DS from AD. Deciphering AD-DS pathogenesis necessitates deciphering which APP products contribute and how.

The horseshoe kidney: Surgical anatomy and embryology

Horseshoe kidneys are a common, yet enigmatic, renal malformation. This review critically appraised the literature surrounding the embryology, etiology and clinical anatomy of horseshoe kidneys. The systematic literature search produced 104 articles, and 56 primary and further secondary references. There were several etiological theories regarding horseshoe kidneys. The established view was that during ascent, the kidneys come into close apposition as they pass through an arterial fork. Another possible mechanism related to lateral flexion of the trunk or rotation of the caudal embryo; the association of asymmetrical horseshoe kidneys with a number of vertebral conditions supported this hypothesis. More recent animal models implicated the notochord and sonic hedgehog signaling. Furthermore, it has been suggested that the isthmus may be the result of ectopic mesenchymal tissue. Surgical anatomy of the horseshoe kidney is complex, due to variability in location, orientation and blood supply. Both arterial and venous anatomy is highly variable. This raised the question of whether anomalous blood supply is the cause or result of abnormal renal position. In the majority of cases, the isthmus contained functional renal parenchyma. In over 90% of cases, fusion between the kidneys occurred at the lower pole. Despite commonly being quoted as 'held back by the inferior mesenteric artery' at L3, in reality the isthmus was only found immediately inferior to this in 40% of cases.

Calretinin-Immunoreactive Hypoinnervation in Down Syndrome (DS): Report of an Infant with Very Short-Segment Hirschsprung Disease and Comparison to Biopsy Findings in 20 Normal Infants and 11 Infants with DS and Chronic Constipation

In Down syndrome (DS) constipation is common, and the incidence of Hirschsprung disease (HD) is 1-2%. Rectal suction biopsies (RSBs) in DS may show discordant features; calretinin immunoreactivity (CRir) often helps resolve discrepancies. We report a case of unequivocal very short-segment HD (vsHD) in an infant with DS who had aganglionosis with abnormal acetylcholine esterase (AChE) activity in 3 RSBs. The CRir patterns were scanty positive rather than the expected absent CRir innervation in the lamina propria (LP). The resection specimen was grossly typical for short-segment HD, with a 5.5-cm, narrow but normally ganglionated segment proximal to the verified very short distal anganglionic zone. Unequivocal calretinin hypoinnervation was limited to the distal 2 cm, substantiating the warning of Kapur that small numbers of CRir nerves in the LP do not exclude a diagnosis of vsHD. We evaluated RSBs from 11 DS and 20 randomly selected normal infants <6 months of age with chronic constipation. The normal infants had abundant mucosal calretinin innervation and AChE histochemistry. We observed variable CRir hypoinnervation in RSBs in DS infants (including 6/7 with "normal" original diagnosis and 1/4 with HD). Our findings caution against overdependence on "normal" calretinin immunohistochemistry and suggest that AChE may be more reliable than CRir in the context of DS. An unknown number of patients with DS may have enteric nervous system disorders functionally similar to HD, which are possibly related to abnormal or imbalanced autonomic innervation, of which distal calretinin hypoinnervation is one manifestation, despite the presence of ganglia.

The Incidence of Cardiac Lesions among Children with Down's Syndrome in Jamaica - A Prospective Study

OBJECTIVES

This study aimed to define the incidence of Down's syndrome and to describe the epidemiology of cardiac lesions in Jamaican children with Down's syndrome.

METHODS

A prospective study was conducted on 53 infants during the period January 1, 2007 to December 31, 2007, at the Bustamante Hospital for Children, Kingston, Jamaica. A medical history, physical examination and echo Doppler was performed on each child.

RESULTS

Forty-six thousand babies were born in Jamaica in 2007, of which 53 infants were diagnosed with Down's syndrome, giving an incidence of 1:868. Forty-two (79.2%) infants had congenital heart lesions. Of the 42 patients with cardiac lesions, 50% had an isolated cardiac lesion while 50% had multiple defects. The most common single defect was the atrioventricular septal defect found in 10 (24%) patients. The most frequent concomitant malformation was a patent ductus arteriosus, found in 16 (38.1%) of the patients. The median age of diagnosis with Down's syndrome was 0.14 weeks (interquartile range (IQR) 0 to 68 weeks). The median age of diagnosis with the cardiac lesion was 15.1 weeks (IQR 0 to 40.0 weeks).

CONCLUSIONS

The incidence of Down's syndrome in Jamaica is similar to the reported international experience. The distribution of cardiac malformations is similar to other countries; however, the main difference is the higher incidence of congenital heart disease and a higher incidence of combined lesions.

The pattern of congenital heart defects arising from reduced Tbx5 expression is altered in a Down syndrome mouse model

BACKGROUND

Nearly half of all individuals with Down Syndrome (DS) have some type of congenital heart defect (CHD), suggesting that DS sensitizes to CHD but does not cause it. We used a common mouse model of DS, the Ts65Dn mouse, to study the contribution of Tbx5, a known modifier of CHD, to heart defects on a trisomic backgroun. Mice that were heterozygous for a Tbx5 null allele were crossed with Ts65Dn mice. Thoraxes of progeny were fixed in 10% formalin, embedded in paraffin, and sectioned for analysis of CHD. Gene expression in embryonic hearts was examined by quantitative PCR and in situ hybridization. A TBX5 DNA binding site was verified by luciferase assays.

METHODS

Mice that were heterozygous for a Tbx5 null allele were crossed with Ts65Dn mice. Thoraxes of progeny were fixed in 10% formalin, embedded in paraffin, and sectioned for analysis of CHD. Gene expression in embryonic hearts was examined by quantitative PCR and in situ hybridization. A TBX5 DNA binding site was verified by luciferase assays.

RESULTS

We crossed mice that were heterozygous for a Tbx5 null allele with Ts65Dn mice. Mice that were trisomic and carried the Tbx5 mutation (Ts65Dn;Tbx5 (+/-) ) had a significantly increased incidence of overriding aorta compared to their euploid littermates. Ts65Dn;Tbx5 (+/-) mice also showed reduced expression of Pitx2, a molecular marker for the left atrium. Transcript levels of the trisomic Adamts1 gene were decreased in Tbx5 (+/-) mice compared to their euploid littermates. Evidence of a valid binding site for TBX5 upstream of the trisomic Adamts1 locus was also shown.

CONCLUSION

Haploinsufficiency of Tbx5 and trisomy affects alignment of the aorta and this effect may stem from deviations from normal left-right patterning in the heart. We have unveiled a previously unknown interaction between the Tbx5 gene and trisomy, suggesting a connection between Tbx5 and trisomic genes important during heart development.

Disruptive behavior in Down syndrome children: a cross-sectional comparative study

BACKGROUND AND OBJECTIVES

Down syndrome (DS) is associated with intellectual disability, and patients with DS show significant psychopathology. The objectives of this study were to estimate the prevalence of disruptive behavior in DS patients compared to their siblings, and to find any association between the disruptive behavior and the degree of intelligence.

DESIGN AND SETTINGS

This is a cross-sectional comparative study done in Mansoura University Children's Hospital during the period March 1, 2012-February 28, 2013.

SUBJECTS AND METHODS

In this study, 100 cases of DS and an equal number of their brothers/sisters were enrolled in the study. The Arabic version of Vineland Adaptive Behavior Scale was used for assessing social and mental intelligence quotient (IQ). The Arabic version of Mini International Neuropsychiatric Interview for Children (MINI-KID) and disruptive behavior disorder (DBD) rating scale were used for assessing disruptive behavior disorders.

RESULTS

Both social and mental IQs were significantly higher in non-DS than in DS cases. The prevalence of different variants of attention deficit/hyperactive disorder (ADHD)-impulsive, inattentive, and combined types-was significantly lower in non-DS than in DS cases; however, there was no statistical difference between both groups as regards oppositional defiant disorder and conduct disorder (CD). Also among DS cases, impulsive and combined types varied significantly with the degree of their IQ.

CONCLUSION

ADHD was more common among DS patients with a special impact of IQ on the type of psychiatric illness. We recommend psychiatric assessment for DS patients as a part of multidisciplinary management.

National growth charts for United Arab Emirates children with Down syndrome from birth to 15 years of age

Background

Specific centile growth charts for children with Down syndrome (DS) have been produced in many countries and are known to differ from those of normal children. Since growth assessment depends on the growth pattern characteristic for these conditions, disorder-specific charts are desirable for various ethnic groups.

Aims

To provide cross-sectional weight, height, and head circumference (HC) references for healthy United Arab Emirates (UAE) children with DS.

Methods

A retrospective and cross-sectional growth study of Emirati children with DS, aged 0 to 18 years old, was conducted. Height, weight, and HC were measured in each child. Cole’s LMS statistical method was applied to estimate age-specific percentiles, and measurements were compared to UAE reference values for normal children.

Results

Incidence of DS in the UAE population is 1 in 374 live births (267 in 10 000 live births). We analyzed 1263 growth examinations of 182 children with DS born between 1994 and 2012. The male-to-female ratio was 1.6:1. Height, weight, and HC centile charts were constructed for ages 0 to 13 years. The prevalence of overweight and obesity in DS children aged 10 to 13 years of age was 32% and 19%, respectively. The DS children were significantly shorter and heavier than normal children in the UAE.

Conclusions

Weight, height, and HC growth charts were created for children with DS. These can be used as a reference standard for the UAE children with DS. Overweight and obesity are quite common in DS children ≥10 years of age, as DS children tend to be shorter and heavier than non-DS children.

Cytogenetic and comorbidity profile of Down syndrome in Mansoura University Children's Hospital, Egypt

BACKGROUND:

Down syndrome (DS) is the most common chromosomal disorder. It has three chromosomal patterns.

AIM:

To determine the cytogenetic and comorbidity profiles of DS in the Genetic Unit of Mansoura University Children's Hospital, Mansoura, Egypt.

MATERIALS AND METHODS:

A retrospective analysis was performed on the case records of 712 cytogenetically diagnosed cases of DS at the Genetic Unit of Mansoura University Children's Hospital, Egypt, during a 10-year period.

RESULTS:

About 19% of the cases had one or more cardiac anomalies and about 8% were hypothyroid. Nondisjunction was the most common type of abnormality, followed by translocation and lastly mosaic: 96.1, 3.1, and 0.8%, respectively. Hypothyroidism was significantly more common in translocation and mosaic karyotypes than in the nondisjunction karyotypes. First and second birth orders were significantly higher in the translocation and mosaic groups than in the nondisjunction group. Mothers are significantly older at the index pregnancy in the nondisjunction group than in the other two groups. We compared our findings with those of previous studies.

CONCLUSION:

Knowing karyotype of DS will help in genetic counseling of the parents. Wide-scale national community-based survey with DS registry could help in estimating the size of the problem.

Maternal smoking and twinning

In order to investigate a possible association between maternal smoking during pregnancy and twinning, information on 1 096 330 single births and 12 342 twin births in 1983–95 was obtained from the Swedish Medical Birth Registry (MBR). All odds ratios (OR) were estimated after stratification for year of birth and maternal age, parity, and educational level. Smoking women, compared with non-smoking women, were at increased risk of having dizygotic (DZ) twins, but the risk increase was only evident among multiparas. A strong association between previous involuntary childlessness and dizygotic (DZ) twinning (especially in primiparas) was found. The strongest association between maternal smoking and DZ twinning was found among multiparas without any history of involuntary childlessness (OR: 1.35, 95%CI:1.22–1.49), whereas among women who had experienced involuntary childlessness, the opposite was seen (OR: 0.82, 95%CI:0.66–1.00, no difference between parity strata). Weinberg's differential method was used to estimate the number of monozygotic (MZ) twins, and a method of estimating stratified ORs among mothers of MZ twins was presented. No association was found between MZ twinning and maternal smoking (OR: 0.96, 95%CI:0.86–1.07), and no confounding by parity or previous involuntary childlessness was indicated. Several non-causal explanations to the positive association between DZ twinning and maternal smoking among multiparas were discussed, but homogeneity over strata indicated that maternal smoking may be a true risk factor for double ovulation.

Effect of communication strategy on personal risk perception and treatment adherence intentions

Past research suggests that semantic and numerical medical risk descriptors may lead to miscommunication and misinterpretation of risk. However, little research has been conducted on systematic features of this bias, and the resulting potential risks to people contemplating or receiving treatment. Three studies explore the influence of verbal versus numerical medical risk descriptions. In Study 1a, San Francisco Bay area residents (N = 59) were presented with semantic descriptors for low-likelihood events and reported their perceived quantitative risk for the events. In Study 1b, undergraduates (N = 29) were presented with semantic versus numerical information about side effects for a prescribed medication and reported their perceived risk and adherence intentions. In Study 1c, San Francisco Bay area residents (N = 125) were presented with semantic versus numerical information about their risk for a disease and reported their perceived risk and intention to adhere to a prescribed treatment. The results of the first study suggest that people systematically overestimate the likelihood of low probability events described in semantic terms such as "low risk" or "people may occasionally experience." The results of the second and third experiment suggest that presenting semantic information about the risks of engaging in a new behavior makes people less likely to engage in that behavior, whereas presenting semantic information about the risks of not engaging in a new behavior makes people more likely to engage in the behavior. The decision to present semantic versus probabilistic information is tantamount to a decision about whether to encourage risk acceptance versus risk avoidance.

A study of congenital cardiac disease in a neonatal population--the validity of echocardiography undertaken by a neonatologist

OBJECTIVES

To estimate the incidence of, and profile the spread of, congenital cardiac defects, and to assess the accuracy of the echocardiographic diagnosis as performed by a neonatologist.

DESIGN

Hospital-based study.

METHODS

All neonates meeting our criterions, specifically those with a persistent murmur 48 hours after birth, underwent an echocardiographic examination to exclude an underlying congenital cardiac defect. All scans performed by the neonatologist were videotaped and reviewed by a paediatric cardiologist. We assessed concordance according to inter-rater agreement.

RESULTS

Out of 11,085 live births, there were 83 infants with a congenital cardiac defect, giving an incidence of 7.49 per 1000 live births, with 95% confidence interval from 5.88 to 9.09. Of the infants with a murmur persisting at or greater than 48 hours after birth, who had a median age of 4.5 days, 75% had a congenital heart defect, with ventricular septal defect being the commonest, encountered in 56.7% of cases. Concordance between the neonatologist and the cardiologist was good, with Cohen's Kappa coefficient being calculated at 0.68, and 95% confidence interval from 0.51 to 0.85.

CONCLUSION

The incidence of congenital cardiac malformations as determined in our hospital-based study in the United Arab Emirates is similar to that described in the Gulf region and worldwide. A persistent murmur at or greater than 48 hours after birth is strongly suggestive of an underlying congenital cardiac malformation. Our experience shows that a neonatologist appropriately trained in echocardiography can perform as well as a paediatric cardiologist. Where specialist resources are limited, this allows for early diagnosis, earlier referral if necessary, and early institution of appropriate therapy.

Effect of maternal smoking and coffee consumption on the risk of having a recognized Down syndrome pregnancy

To evaluate the possible effects of maternal smoking and caffeine or coffee consumption on the occurrence of a recognized pregnancy with Down syndrome, the authors analyzed data from a case-control study of 997 liveborn infants or fetuses with Down syndrome ascertained in California from 1991 to 1993 and 1,007 liveborn controls without a birth defect. Interviews with mothers covered demographic information, pregnancy, and medical history, with detailed questions on the use of tobacco, alcohol, and caffeinated beverages. All analyses were age-adjusted. High alcohol consumption (> or =4 drinks/week) in the first month of pregnancy was associated with reduced risk for a recognized Down syndrome conceptus (odds ratio (OR) = 0.54; 95% confidence interval (CI): 0.34, 0.85). Maternal smoking during the periconceptional period was not associated with risk of recognized Down syndrome (OR = 1.04; 95% CI: 0.79, 1.37), but maternal consumption of four or more cups of coffee per day was inversely associated (OR = 0.63; 95% CI: 0.41, 0.96). In multivariate analysis, a significant interaction between coffee drinking and smoking was observed. The inverse association remained only for nonsmoking mothers who drank four or more cups of coffee per day (OR = 0.48; 95% CI: 0.28, 0.82). These results suggest that among nonsmoking mothers, high coffee consumption is more likely to reduce the viability of a Down syndrome conceptus than that of a normal conceptus.

Seasonal variation in the prevalence of Down syndrome at birth: a review

STUDY OBJECTIVE

Many studies on seasonality in Down syndrome (DS) have been performed and have come to different conclusions. It is suggested that seasonal variation in hormone production by the hypothalamus-pituitary-ovarian axis just before ovulation leads to seasonality in conception rates of DS. This study aimed to determine whether there is seasonal variation in the prevalence of DS at birth as a proxy for seasonality in DS at conception.

DESIGN

All the English and Dutch articles on this topic were reviewed. Articles published between 1966 and January 1996 were traced by Medline, and by the reference lists.

MAIN RESULTS

Twenty articles met the criteria for inclusion. Although seven of these studies reported seasonality in DS prevalence, no consistent seasonal pattern was found in DS at birth in these studies, or in the remaining studies. A seasonal pattern could not have been masked by the effects of maternal age, induced abortions, shortened gestation, or misclassification of DS.

CONCLUSION

Seasonality in the prevalence of DS at birth does not exist. Evidence did not support the suggestion that DS occurrence is related to seasonality in hormone production.

Taking account of vaginal bleeding in screening for Down's syndrome

OBJECTIVE

To derive a method for revising the risk of Down's syndrome in maternal serum marker screening when there is vaginal bleeding. The effect on screening performance of routinely allowing for the presence or absence of bleeding in all women is also assessed.

DESIGN

Overview of published studies on the rate of reported vaginal bleeding in pregnancies with Down's syndrome, on the rate according to maternal age and on the association of bleeding with alpha-fetoprotein (AFP) level. The publications are supplemented with data on unconjugated oestriol (uE3), human chorionic gonadotrophin (hCG) and AFP levels in a consecutive series of screened women.

SETTING

Routine Down's syndrome screening tests carried out on women having antenatal care at the St James's University Hospital, Leeds.

SUBJECTS

Eight hundred and nine screened women.

RESULTS

In five studies the rate of vaginal bleeding in Down's syndrome pregnancies was 1.7 times that in unaffected pregnancies on average. In three studies, the vaginal bleeding rate increased proportionally by 2.2% on average for each year of maternal age. Three studies and our own data were consistent with a 10% increase in the mean AFP level associated with vaginal bleeding, but it did not appear to materially alter uE3 and hCG levels or the standard deviations and correlation coefficients for any of the three analytes. An individual woman's risk was calculated by multiplying her age-specific odds of Down's syndrome by two likelihood ratios, one relating to the vaginal bleeding itself and one from the marker levels. Routine allowance for the presence or absence of vaginal bleeding was estimated to increase the detection rate by less than 1%.

CONCLUSION

Our method is of clinical value in revising the risk when there is concern that vaginal bleeding might be responsible for a negative maternal serum Down's syndrome screening result. A policy of routinely incorporating information on vaginal bleeding in risk estimation for all women would have too small an effect on overall screening performance to recommend it.