Characteristics Associated with Autism Spectrum Disorder Risk in Individuals with Down Syndrome

Intricacies of aging and Down syndrome

Down syndrome is the most frequently occurring genetic condition, with a substantial escalation in risk associated with advanced maternal age. The syndrome is characterized by a diverse range of phenotypes, affecting to some extent all levels of organization, and its progeroid nature - early manifestation of aspects of the senile phenotype. Despite extensive investigations, many aspects and mechanisms of the disease remain unexplored. The current review aims to provide an overview of the main causes and manifestations of Down syndrome, while also examining the phenomenon of accelerated aging and exploring potential therapeutic strategies.

Autism Among Adults with Down Syndrome: Prevalence, Medicaid Usage, and Co-Occurring Conditions

Our objective was to examine occurrence of both conditions in Medicaid; and compare Medicaid service use and cost, and chronic conditions among adults with Down syndrome and autism to those with Down syndrome alone and those with autism alone. We used ICD9 and ICD10 codes in Medicaid claims and encounters from 2011 to 2019 to identify autism and Down syndrome in adults > 18 years. We then calculated costs, claims, hospitalizations, long term care days, and chronic conditions, and compared by group- autism alone, Down syndrome alone, Down syndrome + autism. Between 2011 and 2019, there were 519,450 adult Medicaid enrollees who met our criteria for autism (N = 396,426), Down syndrome (N = 116,422), or both Down syndrome and autism (N = 6,602). In 2011, 4.1% of enrollees with Down syndrome had co-occurring autism; by 2011 it was 6.6%. The autism group had the fewest claims and inpatient hospitalizations, followed by the Down syndrome group, then the Down syndrome + autism group. After age adjustment, those with Down syndrome alone and Down syndrome + autism had elevated prevalence of atrial fibrillation, dementia, heart failure, kidney disease, and obesity compared to the autism alone group. Both groups also had decreased occurrence of depression and hypertension compared to the autism alone group. Prevalence of autism is higher among people with Down syndrome than in peers. The increased costs and service use for those with both conditions highlight the extent to which this population need health care and signal the need for more effective preventative care and therapies.

Prediction of chromosomal abnormalities in the screening of the first trimester of pregnancy using machine learning methods: a study protocol

BACKGROUND

For women in the first trimester, amniocentesis or chorionic villus sampling is recommended for screening. Machine learning has shown increased accuracy over time and finds numerous applications in enhancing decision-making, patient care, and service quality in nursing and midwifery. This study aims to develop an optimal learning model utilizing machine learning techniques, particularly neural networks, to predict chromosomal abnormalities and evaluate their predictive efficacy.

METHODS/ DESIGN

This cross-sectional study will be conducted in midwifery clinics in Mashhad, Iran in 2024. The data will be collected from 350 pregnant women in the high-risk group who underwent screening tests in the first trimester (between 11-14 weeks) of pregnancy. Information collected includes maternal age, BMI, smoking habits, history of trisomy 21 and other chromosomal disorders, CRL and NT levels, PAPP-A and B-HCG levels, presence of insulin-dependent diabetes, and whether the pregnancy resulted from IVF. The study follows up with the women during their clinic visits and tracks the results of amniocentesis. Sampling is based on Convenience Sampling, and data is gathered using a checklist of characteristics and screening/amniocentesis results. After preprocessing, feature extraction is conducted to identify and predict relevant features. The model is trained and evaluated using K-fold cross-validation.

DISCUSSION

There is a growing interest in utilizing artificial intelligence methods, like machine learning and deep learning, in nursing and midwifery. This underscores the critical necessity for nurses and midwives to be well-versed in artificial intelligence methods and their healthcare applications. It can be beneficial to develop a machine learning model, specifically focusing on neural networks, for predicting chromosomal abnormalities.

ETHICAL CODE

IR.MUMS.NURSE.REC. 1402.134.

Autism Spectrum Disorder in Down Syndrome: Experiences from Caregivers

This study aimed to learn about the experiences of families of individuals with a dual diagnosis of Down syndrome (DS) and autism spectrum disorder (ASD) (DS-ASD), and to document the journey from early concerns to diagnosis and intervention. Caregivers completed an online survey describing their journey raising a child with DS-ASD. Survey responses were analyzed qualitatively and coded into categories to highlight common themes. Stereotypy, severe communication impairments, and behavioral difficulties prompted caregivers to pursue further evaluation. There was a mean 4.65-year gap between first noticing symptoms and receiving an ASD diagnosis. Several therapeutic interventions were identified as beneficial, including behavioral and communication support. Caregivers expressed frustration and described high levels of stress and social isolation. The diagnosis of ASD in children with DS is often delayed, and caregivers' initial concerns are frequently dismissed. Raising a child with DS-ASD can lead to social isolation and elevated caregiver stress. More research is needed to tailor diagnostic algorithms and therapeutic interventions to the unique needs of this patient population. Caregivers yearn for improved understanding of DS-ASD, more targeted therapies and educational programs, and more overall support.

Pragmatic competence in people with dual diagnosis: down syndrome and autism spectrum disorder

BACKGROUND

Pragmatics is an area that can be affected in a wide variety of disorders. In this sense, Syndromic Autism is defined as a disorder in which a causal link is established between an associated syndrome and Autism Spectrum Disorder (ASD). Likewise, Down Syndrome (DS) is one of the main genetically based syndromes in which ASD is described as one of its possible manifestations. In this direction, people with DS are described as social beings whereas in ASD there seems to be a specific alteration of this domain.

METHODS

In this study, pragmatic performance was analysed in a sample of 72 participants, where comparisons were made between the scores obtained by children with ASD (n = 24), with DS (n = 24) and with DS + ASD (n = 24).

RESULTS

The Social Communication Questionnaire (SCQ), the Block Objective and Criterial Language Battery (BLOC-SR) and the Neuropsychology subtest (NEPSY-II) aimed at Theory of Mind (ToM) identified significant differences between the groups. However, two-to-two comparisons reported no significant differences between DS and DS + ASD.

CONCLUSIONS

Although several studies report differences between the three proposed groups, our data seem to suggest that ASD symptomatology in DS is associated with Intellectual Developmental Disorder (IDD). However, the lack of solid scientific evidence regarding comorbid diagnosis makes further research along these lines indispensable.

TRIAL REGISTRATION

This study was approved by the Ethics Committee for Social Research at UCLM with reference CEIS-704,511-L8M4.

Associations Among Sex, Cognitive Ability, and Autism Symptoms in Individuals with Down Syndrome

This study explores sex-differences in (a) rates and profiles of autism symptoms as well as in (b) the contribution of intellectual quotient (IQ) to autism symptom presentation in Down syndrome (DS). Participants were 40 males and 38 females with DS, aged 6 to 23 years. Autism symptoms were rated through the Autism Diagnostic Observation Schedule-Second Edition (ADOS-2). Results show no sex differences in the ADOS-2 Calibrated Severity Scores (CSS). However, only females with DS who are classified as DS-Only have higher scores on verbal IQ than those classified as DS + autism. Furthermore, associations between IQ and all CSSs are found for females, but not for males. Findings suggest that verbal cognition may play differential roles for females and males with DS.

Heterogeneity of Autism Characteristics in Genetic Syndromes: Key Considerations for Assessment and Support

Purpose of Review

Elevated prevalence of autism characteristics is reported in genetic syndromes associated with intellectual disability. This review summarises recent evidence on the behavioural heterogeneity of autism in the following syndromes: Fragile X, Cornelia de Lange, Williams, Prader-Willi, Angelman, Down, Smith-Magenis, and tuberous sclerosis complex. Key considerations for assessment and support are discussed.

Recent Findings

The profile and developmental trajectory of autism-related behaviour in these syndromes indicate some degree of syndrome specificity which may interact with broader behavioural phenotypes (e.g. hypersociability), intellectual disability, and mental health (e.g. anxiety). Genetic subtype and co-occurring epilepsy within syndromes contribute to increased significance of autism characteristics. Autism-related strengths and challenges are likely to be overlooked or misunderstood using existing screening/diagnostic tools and criteria, which lack sensitivity and specificity within these populations.

Summary

Autism characteristics are highly heterogeneous across genetic syndromes and often distinguishable from non-syndromic autism. Autism diagnostic assessment practices in this population should be tailored to specific syndromes. Service provisions must begin to prioritise needs-led support.

Using the Social Skills Improvement System (SSiS) Rating Scales to assess social skills in youth with Down syndrome

Introduction and Methods

This study provides preliminary data on the Social Skills Improvement System (SSiS) Rating Scales Parent Form to measure social skills in a sample of 124 children and adolescents with Down syndrome (DS) ages 6–17 years.

Results

Overall, participants demonstrated relatively mild symptoms, with the sample’s average standard score falling within 1 standard deviation from the mean of the normative sample for the social skills (M = 92, SD = 15) and problem behaviors (M = 104, SD = 12) domains (normative sample M = 100, SD = 15 for both domains). However, a wide range of scores was observed across the sample for the composite and subscale scores. Differential patterns were also observed by subscale. For some subscales (i.e., Cooperation, Assertion, Responsibility, Engagement, Externalizing, Hyperactivity/Inattention, and Autism Spectrum), a disproportionate number of participants scored in the below average (i.e., lower levels of social skills) or above average (i.e., more symptomatic in problem behaviors or autism spectrum) range relative to the normative sample; for other subscales (i.e., Communication, Empathy, Self-Control, Bullying, and Internalizing), participants’ score distribution aligned more closely to that of the normative sample. SSiS composite scores correlated in the expected directions with standardized measures of autism characteristics, executive function, and expressive language.

Discussion

This study provides some of the first evidence validating the use of the SSiS in youth with DS, filling a gap in standardized measures of social functioning in this population.

Developmental Functioning of Toddlers At-Risk for Autism With and Without Down Syndrome

PURPOSE

Due to the difficulties in differentiating between impairments associated with intellectual disability and ASD symptomology, DS often leads to delayed or misdiagnoses of ASD.

METHOD

An ANOVA was run to investigate the effects of ASD risk and DS on overall developmental functioning across three groups: ASD+, DS-, and DS+ (n = 138). A MANOVA was run to investigate the differences of group on five developmental subdomains.

RESULTS

The results revealed significant group differences in the overall developmental functioning and each developmental subdomain. Children in the DS+ group demonstrated significantly lower overall developmental functioning, as well as lower adaptive, cognitive, motor, and communication skills compared to their peers; however, children in the DS- group demonstrated significantly better social skills compared to their peers in the ASD+ group.

DISCUSSION

These findings support the need for early screening and identification of ASD among those with DS.

Patterns and predictors of adaptive skills in 2- to 7-year-old children with Down syndrome

Background

There is substantial variability in adaptive skills among individuals with Down syndrome. Few studies, however, have focused on the early developmental period or on the potential sources of variability in adaptive skills. This study characterizes adaptive skills in young children with Down syndrome and investigates child characteristics associated with adaptive skills.

Methods

Participants were 44 children with Down syndrome ranging in age from 2.50 to 7.99 years (M = 4.66 years, SD = 1.46). The Vineland Adaptive Behavior Scales-3 (VABS-3) Comprehensive Interview Form was used to assess adaptive behavior in the three core domains: socialization, daily living, and communication skills. Caregivers also reported on motor skills and autism spectrum disorder symptoms. Child cognitive abilities were assessed.

Results

Analyses comparing mean standard score performance across the three VABS-3 core domains demonstrated significant differences between all pairs of domains, resulting in a group-level pattern of socialization > daily living > communication skills. At the individual level, 10 different patterns of relative strength and weakness were identified, with only 18% of participants evidencing significant differences between adaptive skill domain standard scores corresponding to the group-level pattern of significant differences. Child characteristics (cognitive abilities, motor skills, and autism spectrum disorder symptoms) were significantly associated with VABS-3 adaptive domain standard scores.

Conclusion

These findings underscore the importance of individualizing intervention programs focused on improving the adaptive skills of young children with Down syndrome based on consideration of the child’s relative adaptive strengths and weaknesses.

Latent profiles of autism symptoms in children and adolescents with Down syndrome

BACKGROUND

Down syndrome (DS) is associated with elevated rates of autism spectrum disorder (ASD) and autism symptomatology. To better characterise heterogeneity in ASD symptomatology in DS, profiles of caregiver-reported ASD symptoms were modelled for children and adolescents with DS.

METHODS

Participants (n = 125) were recruited through several multi-site research studies on cognition and language in DS. Using the Social Responsiveness Scale-2 (SRS-2; Constantino and Gruber 2012), two latent profile analyses (LPA) were performed, one on the broad composite scores of social communication and interaction and restricted interests and repetitive behaviour, and a second on the four social dimensions of social communication, social motivation, social awareness, and social cognition.

RESULTS

A three-profile model was the best fit for both analyses, with each analysis yielding a low ASD symptom profile, an elevated or mixed ASD symptom profile and a high ASD symptom profile. Associations were observed between profile probability scores and IQ, the number of co-occurring biomedical conditions reported, sex, and SRS-2 form.

CONCLUSIONS

Characterising heterogeneity in ASD symptom profiles can inform more personalised supports in this population, and implications for potential therapeutic approaches for individuals with DS are discussed.

Prenatal and Postnatal Pharmacotherapy in Down Syndrome: The Search to Prevent or Ameliorate Neurodevelopmental and Neurodegenerative Disorders

Those with Down syndrome (DS)-trisomy for chromosome 21-are routinely impacted by cognitive dysfunction and behavioral challenges in children and adults and Alzheimer's disease in older adults. No proven treatments specifically address these cognitive or behavioral changes. However, advances in the establishment of rodent models and human cell models promise to support development of such treatments. A research agenda that emphasizes the identification of overexpressed genes that contribute demonstrably to abnormalities in cognition and behavior in model systems constitutes a rational next step. Normalizing expression of such genes may usher in an era of successful treatments applicable across the life span for those with DS.

Symptoms of Autism Spectrum Disorder in Individuals with Down Syndrome

There is a growing body of evidence to suggest that individuals with Down syndrome (DS) are diagnosed with autism spectrum disorders (ASD) at a higher rate than individuals in the general population. Nonetheless, little is known regarding the unique presentation of ASD symptoms in DS. The current study aims to explore the prevalence and profiles of ASD symptoms in a sample of individuals with DS (n = 83), aged between 6 and 23 years. Analysis of this sample (MAge = 15.13) revealed that approximately 37% of the sample met the classification cut-off for ASD using the Autism Diagnostic Observation Schedule 2 (ADOS-2) Calibrated Severity Score (CSS), an indicator of the participants' severity of ASD-related symptoms. Item-level analyses revealed that multiple items on Module 2 and Module 3 of the ADOS-2, mostly in the Social Affect (SA) subdomain, differentiated the children with DS who did not meet ASD classification (DS-only) from those who did (DS + ASD). Lastly, comparisons of individuals with DS-only and those with DS + ASD differed significantly on the syntactic complexity of their expressive language. These findings shed light on the unique presentation of ASD symptoms in a sample of individuals with DS and suggest that expressive language abilities may play a pivotal role in the presentation of ASD symptoms in DS.

Relationship between Apgar scores and long-term cognitive outcomes in individuals with Down syndrome

This study examined the contribution of the Apgar score at 1 and 5 min after birth to later cognitive functioning in 168 individuals with Down syndrome who were between 6 and 25 years of age at time of cognitive testing. Our results showed that a lower Apgar score at 1 min was related to a worse performance in later cognitive measures of receptive vocabulary, verbal comprehension and production, visual memory and working memory. Results also showed that a lower Apgar score at 5 min was only related to worse later outcomes of verbal comprehension and production and auditory working memory. Our findings suggest a need for future studies investigating how specific perinatal events reflected in the Apgar score are linked to later cognitive functioning in individuals with Down syndrome.

Co-occurring Down Syndrome and Autism Spectrum Disorder: Cognitive, Adaptive, and Behavioral Characteristics

The current study explores functioning in individuals with co-occurring Autism Spectrum Disorder and Down Syndrome (ASD+DS; n = 23), individuals with ASD and cognitive impairment (ASD+ID; n = 99) and individuals with idiopathic ID (n = 38). ANCOVA results revealed that individuals with ASD+DS showed strengths in behavioral functioning compared to individuals with ID and more similar behavioral functioning to those with ASD+ID (η² = 0.12), with the exception of disruptive behaviors. Cognitive functioning (ɸ_c = 0.41) and ASD symptomatology (η² = 0.11) were more comparable for children with ASD+DS and ASD + ID than for individuals with ID. Individuals with ASD+DS had the lowest overall adaptive skills (η² = 0.11). Findings highlight similarities between ASD+DS and ASD+ID groups, emphasizing the importance of ASD identification within the DS population to provide access to specific interventions.

Capturing cognitive and behavioral variability among individuals with Down syndrome: a latent profile analysis

BACKGROUND

There is a high degree of inter- and intra-individual variability observed within the phenotype of Down syndrome. The Down Syndrome Cognition Project was formed to capture this variability by developing a large nationwide database of cognitive, behavioral, health, and genetic information on individuals with Down syndrome, ages 6-25 years. The current study used the Down Syndrome Cognition Project database to characterize cognitive and behavioral variability among individuals with Down syndrome.

METHODS

Latent profile analysis was used to identify classes across a sample of 314 participants based on their cognition (IQ and executive functioning), adaptive and maladaptive behavior, and autism spectrum disorder symptomatology. A multivariate multinomial regression model simultaneously examined demographic correlates of class.

RESULTS

Results supported a 3-class model. Each class demonstrated a unique profile across the subdomains of cognition and behavior. The "normative" class was the largest (n = 153, 48%) and displayed a relatively consistent profile of cognition and adaptive behavior, with low rates of maladaptive behavior and autism symptomatology. The "cognitive" class (n = 109, 35%) displayed low cognitive scores and adaptive behavior and more autism symptomatology, but with low rates of maladaptive behavior. The "behavioral" class, the smallest group (n = 52, 17%), demonstrated higher rates of maladaptive behavior and autism symptomatology, but with cognition levels similar to the "normative" class; their adaptive behavior scores fell in between the other two classes. Household income and sex were the only demographic variables to differ among classes.

CONCLUSIONS

These findings highlight the importance of subtyping the cognitive and behavioral phenotype among individuals with Down syndrome to identify more homogeneous classes for future intervention and etiologic studies. Results also demonstrate the feasibility of using latent profile analysis to distinguish subtypes in this population. Limitations and future directions are discussed.

Exploring Expressive Communication Skills in a Cross-Sectional Sample of Individuals With a Dual Diagnosis of Autism Spectrum Disorder and Down Syndrome

Individuals with a comorbid diagnosis of Down syndrome (DS) and autism spectrum disorder (ASD) have been found to exhibit greater deficits in expressive communication than individuals with DS only. We hypothesized that individuals with a comorbid diagnosis (n = 430) would have significantly lower Communication Matrix scores and specifically social communication scores than individuals with DS alone (n = 4,352). In a sample of 4,782 individuals with DS, scores for individuals with a comorbid diagnosis were on average 18.01 points and 7.26 points lower for total score and social score respectively as compared to individuals with DS. Comorbid diagnosis accounted for 10.5% of the variance in communication scores. Between-group differences in referential gestures and symbolic communication behaviors were also observed.

Down Syndrome and Autism Spectrum Disorder Dual Diagnosis: Important Considerations for Speech-Language Pathologists

Purpose Individuals with Down syndrome (DS) often receive speech-language therapy services starting in infancy or toddlerhood. When providing speech-language therapy services for children with DS, speech-language pathologists (SLPs) need to consider the impact of other developmental and comorbid disorders that can affect language development, such as the presence of a dual diagnosis of DS and autism spectrum disorder (DS + ASD). The prevalence rate of ASD in DS is ~20%, which is higher than in the general population. Method This clinical focus article aims to provide SLPs with additional knowledge about DS + ASD to improve service delivery and support parents' ability to advocate for their child with confirmed or suspected DS + ASD. This is accomplished by summarizing the current evidence base on the presence of ASD in DS and discussing implications of a DS + ASD diagnosis for clinical practice with SLPs. Conclusions SLPs play a key role in supporting families of those with DS + ASD by advocating and educating. By understanding the unique profiles of strengths and weaknesses of individuals with DS + ASD, SLPs can provide appropriate service delivery (i.e., treatment and intervention approaches) and advocacy for their clients and their families.

Abnormalities of synaptic mitochondria in autism spectrum disorder and related neurodevelopmental disorders

Autism spectrum disorder (ASD) is a neurodevelopmental condition primarily characterized by an impairment of social interaction combined with the occurrence of repetitive behaviors. ASD starts in childhood and prevails across the lifespan. The variability of its clinical presentation renders early diagnosis difficult. Mutations in synaptic genes and alterations of mitochondrial functions are considered important underlying pathogenic factors, but it is obvious that we are far from a comprehensive understanding of ASD pathophysiology. At the synapse, mitochondria perform diverse functions, which are clearly not limited to their classical role as energy providers. Here, we review the current knowledge about mitochondria at the synapse and summarize the mitochondrial disturbances found in mouse models of ASD and other ASD-related neurodevelopmental disorders, like DiGeorge syndrome, Rett syndrome, Tuberous sclerosis complex, and Down syndrome.

Gestational age is related to symptoms of attention-deficit/hyperactivity disorder in late-preterm to full-term children and adolescents with down syndrome

Attention-deficit/hyperactivity disorder is frequently reported in individuals with Down syndrome, with considerable variation in the expression and severity of the symptoms. Despite growing evidence that gestational age predicts later symptoms of attention-deficit/hyperactivity disorder in the euploid population, this has not been studied in down syndrome. The current study is designed to investigate the influence of gestational age in later symptoms of attention-deficit/hyperactivity disorder in 105 individuals (49 males and 56 females; aged 6–18 years) with Down syndrome who were born at or after 35 weeks gestation. Maternal age at birth, maternal level of education, household income, as well as sex, chronological age, and cognitive level of the participant with Down syndrome were considered in our analysis. Results from this study show that gestational age is related to inattentive and hyperactive/impulsive symptoms in children and adolescents with Down syndrome. Therefore, gestational age should be addressed when considering symptoms of attention-deficit/hyperactivity disorder, as it may have implications for early interventions. More attention is needed toward the advancement of care and follow-up for infants with down syndrome who are born even late preterm or early term.

Bringing the Laboratory Home: PANDABox Telehealth-Based Assessment of Neurodevelopmental Risk in Children

Background

Advances in clinical trials have revealed a pressing need for outcome measures appropriate for children with neurogenetic syndromes (NGS). However, the field lacks a standardized, flexible protocol for collecting laboratory-grade experimental data remotely. To address this challenge, we developed PANDABox (Parent-Administered Neurodevelopmental Assessment), a caregiver-facilitated, remotely administered assessment protocol for collecting integrated and high quality clinical, behavioral, and spectral data relevant to a wide array of research questions. Here, we describe PANDABox development and report preliminary data regarding: (1) logistics and cost, (2) caregiver fidelity and satisfaction, and (3) data quality.

Methods

We administered PANDABox to a cohort of 16 geographically diverse caregivers and their infants with Down syndrome. Tasks assessed attention, language, motor, and atypical behaviors. Behavioral and physiological data were synchronized and coded offline by trained research assistants.

Results

PANDABox required low resources to administer and was well received by families, with high caregiver fidelity (94%) and infant engagement (91%), as well as high caregiver-reported satisfaction (97% positive). Missing data rates were low for video frames (3%) and vocalization recordings (6%) but were higher for heart rate (25% fully missing and 13% partially missing) and discrete behavioral presses (8% technical issues and 19% not enough codable behavior), reflecting the increased technical demands for these activities.

Conclusion

With further development, low-cost laboratory-grade research protocols may be remotely administered by caregivers in the family home, opening a new frontier for cost-efficient, scalable assessment studies for children with NGS other neurodevelopmental disorders.

The Social Responsiveness Scale (SRS-2) in school-age children with Down syndrome at low risk for autism spectrum disorder

BACKGROUND AND AIMS

Little is known about how autism spectrum disorder (ASD) symptoms present in individuals with Down syndrome (DS). Some behaviors may be symptomatic of comorbid ASD or more broadly representative of the DS phenotype. A prior research study documented elevated ASD-like symptoms in adolescents and young adults with DS without comorbid ASD, using a common ASD risk screening tool-the Social Responsiveness Scale (SRS). The current study applied a similar approach to younger children with DS using the SRS-2. The primary aim was to document patterns of ASD-like symptoms in children with DS at low risk of comorbid ASD to distinguish the symptoms that may be present across DS in general.

METHODS

SRS-2 standard scores were analyzed in a sample of 40 children with DS, 6-11 years old, who were considered to be at low risk for ASD based on the Social Communication Questionnaire (SCQ) screener. Other developmental characteristics (i.e., age, nonverbal IQ, expressive language), social skills, and problem behaviors were also examined across the sample.

RESULTS

SRS-2 scores were significantly elevated in this sample compared to the normative population sample. A pattern of ASD-like symptomatology was observed across SRS-2 subdomains. These findings were similar to the findings of the prior study. However, nuanced differences were observed across the two samples that may represent developmental differences across different ages in this population.

CONCLUSIONS

Replicating and extending a prior study's findings, certain ASD-like behaviors may occur in individuals with DS who are at low risk for comorbid ASD.

IMPLICATIONS

Understanding the pattern of ASD-like behaviors that occur in children with DS who are at low risk for comorbid ASD will help clinicians in screening and identification efforts. In particular, it will lead to better specification of the behaviors or symptoms that are not characteristic of the DS phenotype and thus are red flags for comorbid ASD in this population.

Emerging biomarkers in autism spectrum disorder: a systematic review

Autism spectrum disorder (ASD) affects approximately 2% of children in the United States (US) yet its etiology is unclear and effective treatments are lacking. Therapeutic interventions are most effective if started early in life, yet diagnosis often remains delayed, partly because the diagnosis of ASD is based on identifying abnormal behaviors that may not emerge until the disorder is well established. Biomarkers that identify children at risk during the pre-symptomatic period, assist with early diagnosis, confirm behavioral observations, stratify patients into subgroups, and predict therapeutic response would be a great advance. Here we underwent a systematic review of the literature on ASD to identify promising biomarkers and rated the biomarkers in regards to a Level of Evidence and Grade of Recommendation using the Oxford Centre for Evidence-Based Medicine scale. Biomarkers identified by our review included physiological biomarkers that identify neuroimmune and metabolic abnormalities, neurological biomarkers including abnormalities in brain structure, function and neurophysiology, subtle behavioral biomarkers including atypical development of visual attention, genetic biomarkers and gastrointestinal biomarkers. Biomarkers of ASD may be found prior to birth and after diagnosis and some may predict response to specific treatments. Many promising biomarkers have been developed for ASD. However, many biomarkers are preliminary and need to be validated and their role in the diagnosis and treatment of ASD needs to be defined. It is likely that biomarkers will need to be combined to be effective to identify ASD early and guide treatment.