Diagnosis of Down's syndrome in neonates

Prevalence and Patterns of Congenital Heart Defects and Other Major Non-Syndromic Congenital Anomalies Among Down Syndrome Patients: A Retrospective Study

Background

Children with DS are at higher risk of developing congenital anomalies, particularly cardiac anomalies.

Methods

Medical records of 502 DS patients were reviewed. The logistic regression analyses were performed to determine independent predictors.

Results

Of the total 502 study subjects, 53.4% were males. Only 1.4% of the DS case diagnosis were confirmed by karyotyping. All cases were diagnosed postnatally. The median age at DS diagnosis was 5 months. About 13% were born preterm; 50.2% of the subjects maternal age at conception were thirty-five years and above. Over three-quarters (75.1%) had at least one structural congenital anomaly. Multiple anomalies were diagnosed in 12.8% of the subjects. At least one cardiac congenital anomaly was diagnosed in 67.3% of the study subjects, and 32.8% of them were diagnosed with multiple cardiac anomalies. Patent ductus arteriosus (28.5%), Ventricular septal defect (23.2%), and AVSD (21.9%) were the three common lesions. At least one genitourinary system anomaly was identified in 32 (6.4%) of them. Roughly, 8% of study participants exhibited congenital anomaly of the head, eye, nose, and throat. Anorectal malformation was found as the most common gastrointestinal anomaly. Maternal age at conception was found as independent predictor for presence of structural congenital anomaly (AOR 2.59; 95% CI 1.58-4.23, p-value < 0.01). Advanced maternal age is also found increasing the risk of developing congenital heart defect (AOR 2.37; 95% CI 1.52-3.7, p-value < 0.01).

Conclusion

High prevalence of congenital anomalies has been noted in the current study compared to previous studies. Predictive factors increasing risk of congenital anomalies in DS patients have been identified. The current findings may help in developing strategies and more targeted preventive and therapeutic interventions.

A reassessment of Jackson's checklist and identification of two Down syndrome sub-phenotypes

Down syndrome (DS) is characterised by several clinical features including intellectual disability (ID) and craniofacial dysmorphisms. In 1976, Jackson and coll. identified a checklist of signs for clinical diagnosis of DS; the utility of these checklists in improving the accuracy of clinical diagnosis has been recently reaffirmed, but they have rarely been revised. The purpose of this work is to reassess the characteristic phenotypic signs and their frequencies in 233 DS subjects, following Jackson's checklist. 63.77% of the subjects showed more than 12 signs while none showed less than 5, confirming the effectiveness of Jackson's checklist for the clinical diagnosis of DS. An association between three phenotypic signs emerged, allowing us to distinguish two sub-phenotypes: Brachycephaly, short and broad Hands, short Neck (BHN), which is more frequent, and "non-BHN". The strong association of these signs might be interpreted in the context of the growth defects observed in DS children suggesting decreased cell proliferation. Lastly, cognitive assessments were investigated for 114 subjects. The lack of association between the presence of a physical sign or the number of signs present in a subject and cognitive skills disproves the stereotype that physical characteristics are predictive of degree of ID.

Facial recognition accuracy in photographs of Thai neonates with Down syndrome among physicians and the Face2Gene application

Down syndrome (DS) is typically recognizable in those who present with multiple dysmorphism, especially in regard to facial phenotypes. However, as the presentation of DS in neonates is less obvious, a phenotype-based presumptive diagnosis is more challenging. Recently, an artificial intelligence (AI) application, Face2Gene, was developed to help physicians recognize specific genetic syndromes by using two-dimensional facial photos. As of yet, there has not been any study comparing accuracy among physicians or applications. Our objective was to compare the facial recognition accuracy of DS in Thai neonates, using facial photographs, among physicians and the Face2Gene. Sixty-four Thai neonates at Thammasat University Hospital, with genetic testing and signed parental consent, were divided into a DS group (25) and non-DS group (39). Non-DS was further divided into unaffected (19) and those affected with other syndromes (20). Our results revealed physician accuracy (89%) was higher than the Face2Gene (81%); however, the application was higher in sensitivity (100%) than physicians (86%). While this application can serve as a helpful assistant in facilitating any genetic syndrome such as DS, to aid clinicians in recognizing DS facial features in neonates, it is not a replacement for well-trained doctors.

Minor physical anomalies in adolescents at risk for substance use and early sex

Minor physical anomalies (MPAs) are associated with disruptions of fetal development. We propose that the same genetic compositions that contribute to the presence of MPAs, also predispose individuals to health-compromising behaviors, thus considering MPAs as particular endophenotypes.We developed a screening questionnaire for problematic conduct, substance abuse, and early sexual practice. A total of 108 adolescents (55 males, 50.9%) aged 11 to 19 years were recruited and further divided into case and control groups according to their answers to the questions of health behaviors mentioned above. We then measured their MPAs that included qualitative and quantitative physical features. Stepwise logistic regression and the receiver operating characteristic (ROC) analyses were used to determine the predictive values of MPAs for behavioral outcomes.The obliquity of palpebral fissure and the head MPAs were negatively associated with substance use. In the ROC analysis, the model provided an area under curve (AUC) of 0.91 with prediction indices being 0.89 for sensitivity and 0.85 for specificity. In addition, the feet MPAs and outer canthal distance were positively, whereas the obliquity of palpebral fissure and ear rotation was negatively associated with early sexual practices. The AUC for early sexual practice was 0.91 and the prediction indexes were 0.87 for sensitivity and 0.88 for specificity.Certain MPAs were associated with adolescent substance use and early sex, which suggests a neurodevelopmental etiology for behavioral outcomes.

Down syndrome in diverse populations

Down syndrome is the most common cause of cognitive impairment and presents clinically with universally recognizable signs and symptoms. In this study, we focus on exam findings and digital facial analysis technology in individuals with Down syndrome in diverse populations. Photos and clinical information were collected on 65 individuals from 13 countries, 56.9% were male and the average age was 6.6 years (range 1 month to 26 years; SD = 6.6 years). Subjective findings showed that clinical features were different across ethnicities (Africans, Asians, and Latin Americans), including brachycephaly, ear anomalies, clinodactyly, sandal gap, and abundant neck skin, which were all significantly less frequent in Africans (P < 0.001, P < 0.001, P < 0.001, P < 0.05, and P < 0.05, respectively). Evaluation using a digital facial analysis technology of a larger diverse cohort of newborns to adults (n = 129 cases; n = 132 controls) was able to diagnose Down syndrome with a sensitivity of 0.961, specificity of 0.924, and accuracy of 0.943. Only the angles at medial canthus and ala of the nose were common significant findings amongst different ethnicities (Caucasians, Africans, and Asians) when compared to ethnically matched controls. The Asian group had the least number of significant digital facial biometrics at 4, compared to Caucasians at 8 and Africans at 7. In conclusion, this study displays the wide variety of findings across different geographic populations in Down syndrome and demonstrates the accuracy and promise of digital facial analysis technology in the diagnosis of Down syndrome internationally. © 2016 Wiley Periodicals, Inc.

Postnatal Identification of Trisomy 21: An Overview of 7,133 Postnatal Trisomy 21 Cases Identified in a Diagnostic Reference Laboratory in China

This study describes the cytogenetic characteristics of 7,133 trisomy 21 (Tri21) identified from 247,818 consecutive postnatal cases karyotyped in a single reference laboratory in China for a period of 4 years. The average detection rate of Tri21 is 2.88% ranging from 3.39% in 2011 to 2.52% in 2014. The decreased detection rates over the years might reflect a possible impact of noninvasive prenatal testing applied rapidly in China and elective termination of affected pregnancies. 95.32% of the Tri21 karyotypes are standard Tri21, 4.53% are Robertsonian Tri21, and less than 1% are other Tri21 forms. There are more mosaic Tri21 in older children and adults, consistent with previous observations that clinical features in individuals with mosaic Tri21 are generally milder and easily missed during perinatal period. The male/female (M/F ratio) for the total 7,133 Tri21 cases and for the 6,671 cases with non-mosaic standard Tri21 are 1.50 and 1.53 respectively, significantly higher than the 0.93 for all the 247,818 cases we karyotyped, the 1.30 for the Down syndrome (DS) identified during perinatal period in China, and the 1.20 for the livebirth in Chinese population. In contrast, the mosaic standard Tri21 case has a significantly lower proportion of males when compared with the non-mosaic standard Tri21, indicating different underlying mechanisms leading to their formations. Opposite M/F ratios in different subtypes of ROB Tri21 were observed. A long list of rare or private karyotypes where Tri21 are concurrently present was identified. The large collection of Tri21 cases with a diversity of clinical findings and a wide age range allowed us to determine the frequency of the different karyotypes of Down syndrome in China, given the fact that this kind of national epidemiological data is lacking currently.

Genetics of hereditary neurological disorders in children

Hereditary neurological disorders (HNDs) are relatively common in children compared to those occurring in adulthood. Recognising clinical manifestations of HNDs is important for the selection of genetic testing, genetic testing results interpretation, and genetic consultation. Meanwhile, advances in next generation sequencing (NGS) technologies have significantly enabled the discovery of genetic causes of HNDs and also challenge paediatricians on applying genetic investigation. Combination of both clinical information and advanced technologies will enhance the genetic test yields in clinical setting. This review summarises the clinical presentations as well as genetic causes of paediatric neurological disorders in four major areas including movement disorders, neuropsychiatric disorders, neuron peripheral disorders and epilepsy. The aim of this review is to help paediatric neurologists not only to see the clinical features but also the complex genetic aspect of HNDs in order to utilise genetic investigation confidently in their clinical practice. A smooth transition from research based to clinical use of comprehensive genetic testing in HNDs in children could be foreseen in the near future while genetic testing, genetic counselling and genetic data interpretation are in place appropriately.

Trisomy 21 in one of extremely low birth weight twins

Prematurity is frequently seen in the neonatal intensive care unit, and trisomy 21 is an often diagnosed neonatal disorder. We report a unique case of extremely premature twins, one of whom was ultimately diagnosed with trisomy 21. We were able to examine the neonatal courses and outcomes of these twins, which were similar despite the presence of trisomy 21 in one twin. This is the first report comparing the neonatal course of an infant with trisomy 21 to an unaffected twin in patients born so prematurely, and demonstrates the difficulty of making the diagnosis of trisomy 21 based solely on physical examination in premature infants.

Down syndrome, Turner syndrome, and Klinefelter syndrome: primary care throughout the life span

Down syndrome, Turner syndrome, and Klinefelter syndrome constitute the most common chromosomal abnormalities encountered by primary care physicians. Down syndrome typically is recognized at birth, Turner syndrome often is not recognized until adolescence,and many men with Klinefelter syndrome are never diagnosed. Although each syndrome is caused by an abnormal number of chromosomes, or aneuploidy, they are distinct syndromes with learning disabilities and a predisposition toward autoimmune diseases,endocrinologic disorders, and cancers. Optimal health care requires a thorough knowledge of the unique health risks, psychoeducational needs, functional capabilities, and phenotypic variation associated with each condition. Syndrome-specific health care should complement standard preventive health care recommendations. Checklists and syndrome-specific growth grids should be used. Ongoing communication between specialists and primary care physicians and between pediatric and adult clinicians is essential. Support groups and Internet resources can benefit affected individuals and their families immensely.

Accuracy of the clinical diagnosis of Down syndrome

OBJECTIVES

To determine the accuracy of clinical diagnosis of Down syndrome, identify problems in reaching a diagnosis, to provide recommendations for improvement and estimate a minimum prevalence for all types of Down syndrome.

DESIGN

A retrospective observational study was carried out over a five-year period. Genesis, a database located in the Department of Medical genetics, was used to identify the number of Down syndrome karyotypes including trisomy, translocation, and mosaic sample variants. Age of diagnosis was determined using date of receipt. Karyotyping requests for a clinical diagnosis of Down syndrome were also identified. Patient notes and cytogenetic laboratory reports were used to identify clinical indication for karyotyping.

SETTING

Regional Genetics Centre, covering all cytogenetic analyses for referrals within the entire Northern Ireland population.

RESULTS

208 postnatal cases of Down syndrome were identified, 197 (94.7%) trisomy, 3 (1.45%) translocation, and 8 (3.85%) mosaic variants. 112 (54.8%) were male and 96 (46.2%) female. 268 samples were taken to confirm or exclude a clinical diagnosis of Down syndrome. 185 of these had Down syndrome, 77 were normal, and 6 had another abnormality. 90% and 100% of trisomy and translocation Down syndrome respectively were diagnosed on the basis of clinical features. This fell to 37.5% of mosaic Down syndrome patients being diagnosed clinically (p < 0.001). Simian crease, sandal gap, epicanthic folds, hypotonia, upslanting palpebral fissures, and protruding tongue are the most frequent characteristic features seen. Similarly epicanthic folds, protruding tongue, simian crease and sandal gap, hypotonia, and upslanting palpebral fissures are also described in a significant proportion of karyotypically normal individuals, thus arousing a suspicion of Down syndrome. 89.4% of patients were diagnosed between day 1 and 7 of life. Of 10.6% patients diagnosed after day 7 of life, 7.6% were adults and 3% children. The minimum prevalence was estimated at 167.9 per 100,000, or 1 in 595 births.

CONCLUSION

In a defined population, with a prevalence of around 1 in 600 births, accurate clinical diagnosis occurred in 90%, 100%, and 37.5% of trisomy, translocation, and mosaic patients. 49.5% of patients had one or more of the following phenotypic findings: Simian crease, sandal gap, epicanthic folds, hypotonia, upslanting palpebral fissures, and protruding tongue. However, the same six features aroused a suspicion of Down syndrome in individuals with normal karyotyping, thus causing undue stress and worry to parents. Mosaic cases may be more common than previously recognised, and often do not have dysmorphic features. It is therefore a diagnosis that should always be considered in those who are educationally subnormal without a definitive diagnosis.