Development and validation of a measure of dysmorphology: useful for autism subgroup classification

A bibliometric analysis of global research status and trends in neuromodulation techniques in the treatment of autism spectrum disorder

BACKGROUND

Autism spectrum disorder (ASD) is a neurodevelopmental disease which has risen to become the main cause of childhood disability, placing a heavy burden on families and society. To date, the treatment of patients with ASD remains a complicated problem, for which neuromodulation techniques are a promising solution. This study analyzed the global research situation of neuromodulation techniques in the treatment of ASD from 1992 to 2022, aiming to explore the global research status and frontier trends in this field.

METHODS

The Web of Science (WoS) was searched for literature related to neuromodulation techniques for ASD from 1992 to October 2022. A knowledge atlas to analyze collaboration among countries, institutions, authors, publishing journals, reference co-citation patterns, keyword co-occurrence, keyword clustering, and burst keywords was constructed using Rstudio software, CiteSpace, and VOSviewer.

RESULTS

In total, 392 publications related to the treatment of ASD using neuromodulation techniques were included. Despite some fluctuations, the number of publications in this field has shown a growing trend in recent years. The United States and Deakin University are the leading country and institution in this field, respectively. The greatest contributing authors are Peter G Enticott, Manuel F Casanova, and Paul B Fitzgerald et al. The most prolific and cited journal is Brain Stimulation and the most commonly co-cited journal is The Journal of Autism and Developmental Disorders. The most frequently cited article was that of Simone Rossi (Safety, ethical considerations, and application guidelines for the use of transverse magnetic stimulation in clinical practice and research, 2009). "Obsessive-compulsive disorder," "transcranial direct current stimulation," "working memory," "double blind" and "adolescent" were identified as hotspots and frontier trends of neuromodulation techniques in the treatment of ASD.

CONCLUSION

The application of neuromodulation techniques for ASD has attracted the attention of researchers worldwide. Restoring the social ability and improving the comorbid symptoms in autistic children and adults have always been the focus of research. Neuromodulation techniques have demonstrated significant advantages and effects on these issues. Transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) are new therapeutic methods introduced in recent years, and are also directions for further exploration.

The role of intellectual disability with autism spectrum disorder and the documented cooccurring conditions: A population-based study

Previous research has identified that patterns of cooccurring conditions (CoCs) associated with autism spectrum disorder (ASD) differ based on the presence of intellectual disability (ID). This study explored the association of documented CoCs among 8-year-old children with ASD and ID (ASD+ID, n = 2416) and ASD without ID (ASD-ID, n = 5372) identified by the Autism and Developmental Disabilities Monitoring Network, surveillance years (SYs) 2012 and 2014. After adjusting for demographic variables, record source, surveillance site, and SY, children with ASD+ID, as compared with children with ASD-ID, were more likely to have histories of nonspecific developmental delays and neurological disorders documented in their records but were less likely to have behavioral and psychiatric disorders. ID plays a key role on how children with ASD would experience other CoCs. Our results emphasize how understanding the pattern of CoCs in ASD+ID and ASD-ID can inform comprehensive and multidisciplinary approaches in assessment and management of children in order to develop targeted interventions to reduce possible CoCs or CoCs-related impairments.

17q12 deletion syndrome mouse model shows defects in craniofacial, brain and kidney development, and glucose homeostasis

17q12 deletion (17q12Del) syndrome is a copy number variant (CNV) disorder associated with neurodevelopmental disorders and renal cysts and diabetes syndrome (RCAD). Using CRISPR/Cas9 genome editing, we generated a mouse model of 17q12Del syndrome on both inbred (C57BL/6N) and outbred (CD-1) genetic backgrounds. On C57BL/6N, the 17q12Del mice had severe head development defects, potentially mediated by haploinsufficiency of Lhx1, a gene within the interval that controls head development. Phenotypes included brain malformations, particularly disruption of the telencephalon and craniofacial defects. On the CD-1 background, the 17q12Del mice survived to adulthood and showed milder craniofacial and brain abnormalities. We report postnatal brain defects using automated magnetic resonance imaging-based morphometry. In addition, we demonstrate renal and blood glucose abnormalities relevant to RCAD. On both genetic backgrounds, we found sex-specific presentations, with male 17q12Del mice exhibiting higher penetrance and more severe phenotypes. Results from these experiments pinpoint specific developmental defects and pathways that guide clinical studies and a mechanistic understanding of the human 17q12Del syndrome. This mouse mutant represents the first and only experimental model to date for the 17q12 CNV disorder. This article has an associated First Person interview with the first author of the paper.

Genome-wide rare variant score associates with morphological subtypes of autism spectrum disorder

Defining different genetic subtypes of autism spectrum disorder (ASD) can enable the prediction of developmental outcomes. Based on minor physical and major congenital anomalies, we categorize 325 Canadian children with ASD into dysmorphic and nondysmorphic subgroups. We develop a method for calculating a patient-level, genome-wide rare variant score (GRVS) from whole-genome sequencing (WGS) data. GRVS is a sum of the number of variants in morphology-associated coding and non-coding regions, weighted by their effect sizes. Probands with dysmorphic ASD have a significantly higher GRVS compared to those with nondysmorphic ASD (P = 0.03). Using the polygenic transmission disequilibrium test, we observe an over-transmission of ASD-associated common variants in nondysmorphic ASD probands (P = 2.9 × 10^-3). These findings replicate using WGS data from 442 ASD probands with accompanying morphology data from the Simons Simplex Collection. Our results provide support for an alternative genomic classification of ASD subgroups using morphology data, which may inform intervention protocols.

Connecting phenotype to genotype: PheWAS-inspired analysis of autism spectrum disorder

Autism Spectrum Disorder (ASD) is extremely heterogeneous clinically and genetically. There is a pressing need for a better understanding of the heterogeneity of ASD based on scientifically rigorous approaches centered on systematic evaluation of the clinical and research utility of both phenotype and genotype markers. This paper presents a holistic PheWAS-inspired method to identify meaningful associations between ASD phenotypes and genotypes. We generate two types of phenotype-phenotype (p-p) graphs: a direct graph that utilizes only phenotype data, and an indirect graph that incorporates genotype as well as phenotype data. We introduce a novel methodology for fusing the direct and indirect p-p networks in which the genotype data is incorporated into the phenotype data in varying degrees. The hypothesis is that the heterogeneity of ASD can be distinguished by clustering the p-p graph. The obtained graphs are clustered using network-oriented clustering techniques, and results are evaluated. The most promising clusterings are subsequently analyzed for biological and domain-based relevance. Clusters obtained delineated different aspects of ASD, including differentiating ASD-specific symptoms, cognitive, adaptive, language and communication functions, and behavioral problems. Some of the important genes associated with the clusters have previous known associations to ASD. We found that clusters based on integrated genetic and phenotype data were more effective at identifying relevant genes than clusters constructed from phenotype information alone. These genes included five with suggestive evidence of ASD association and one known to be a strong candidate.

Identification of Autism in Children Using Static Facial Features and Deep Neural Networks

Autism spectrum disorder (ASD) is a complicated neurological developmental disorder that manifests itself in a variety of ways. The child diagnosed with ASD and their parents’ daily lives can be dramatically improved with early diagnosis and appropriate medical intervention. The applicability of static features extracted from autistic children’s face photographs as a biomarker to distinguish them from typically developing children is investigated in this study paper. We used five pre-trained CNN models: MobileNet, Xception, EfficientNetB0, EfficientNetB1, and EfficientNetB2 as feature extractors and a DNN model as a binary classifier to identify autism in children accurately. We used a publicly available dataset to train the suggested models, which consisted of face pictures of children diagnosed with autism and controls classed as autistic and non-autistic. The Xception model outperformed the others, with an AUC of 96.63%, a sensitivity of 88.46%, and an NPV of 88%. EfficientNetB0 produced a consistent prediction score of 59% for autistic and non-autistic groups with a 95% confidence level.

A Multiplex Human Pluripotent Stem Cell Platform Defines Molecular and Functional Subclasses of Autism-Related Genes

Autism is a clinically heterogeneous neurodevelopmental disorder characterized by impaired social interactions, restricted interests, and repetitive behaviors. Despite significant advances in the genetics of autism, understanding how genetic changes perturb brain development and affect clinical symptoms remains elusive. Here, we present a multiplex human pluripotent stem cell (hPSC) platform, in which 30 isogenic disease lines are pooled in a single dish and differentiated into prefrontal cortex (PFC) lineages to efficiently test early-developmental hypotheses of autism. We define subgroups of autism mutations that perturb PFC neurogenesis and are correlated to abnormal WNT/βcatenin responses. Class 1 mutations (8 of 27) inhibit while class 2 mutations (5 of 27) enhance PFC neurogenesis. Remarkably, autism patient data reveal that individuals carrying subclass-specific mutations differ clinically in their corresponding language acquisition profiles. Our study provides a framework to disentangle genetic heterogeneity associated with autism and points toward converging molecular and developmental pathways of diverse autism-associated mutations.

Actionable and incidental neuroradiological findings in twins with neurodevelopmental disorders

While previous research has investigated neuroradiological findings in autism spectrum disorder (ASD) and attention-deficit hyperactivity disorder (ADHD), the entire range of neurodevelopmental disorders (NDDs) has not yet been well-studied using magnetic resonance imaging (MRI). Considering the overlap among NDDs and simultaneous development of the brain and face, guided by molecular signaling, we examined the relationship of actionable and incidental (non-actionable) MRI findings and NDD diagnoses together with facial morphological variants and genetic copy number variants (CNVs). A cross-sectional study was conducted with a twin cohort 8–36 years of age (57% monozygotic, 40% dizygotic), including 372 subjects (46% with NDDs; 47% female) imaged by MRI, 280 with data for facial morphological variants, and 183 for CNVs. Fifty-one percent of participants had MRI findings. Males had a statistically significantly higher percentage of MRI findings (57.7%) compared with females (43.8%, p = 0.03). Twin zygosity was not statistically significantly correlated with incidence or severity of specific MRI findings. No statistically significant association was found between MRI findings and any NDD diagnosis or facial morphological variants; however, MRI findings were statistically significantly associated with the number of CNVs (OR 1.20, 95% CI 1.00–1.44, p = 0.05, adjusted OR for sex 1.24, 95% CI 1.03–1.50, p = 0.02). When combining the presence of MRI findings, facial morphological variants, and CNVs, statistically significant relationships were found with ASD and ADHD diagnoses (p = 0.0006 and p = 0.002, respectively). The results of this study demonstrate that the ability to identify NDDs from combined radiology, morphology, and CNV assessments may be possible. Additionally, twins do not appear to be at increased risk for neuroradiological variants.

Identification of Essential, Equivocal and Complex Autism by the Autism Dysmorphology Measure: An Observational Study

The Autism Dysmorphology Measure is designed for non-expert clinicians. It uses an algorithm to assess 12 body regions and categorizes Autism on the number of dysmorphic regions identified; Essential (≤ 3), Equivocal (4-5) or Complex (≥ 6). We evaluated 200 Indian children with Autism (mean age 3.7 years) in a hospital-based cross-sectional study and compared inter-group profiles. We found 31% Essential, 49% Equivocal and 20% Complex Autism. On comparing results with existing literature, it appeared that genetic ancestry and age significantly influenced dysmorphism and hence categorization. No significant differences were observed between complex and essential autism in epilepsy, severity of autism or development, as reported earlier. These shortcomings make the present tool unsuitable for use in young Indian children with Autism.

Mapping the Relationship between Dysmorphology and Cognitive, Behavioral, and Developmental Outcomes in Children with Autism Spectrum Disorder

Previous studies investigating the association between dysmorphology and cognitive, behavioral, and developmental outcomes among individuals with autism spectrum disorder (ASD) have been limited by the binary classification of dysmorphology and lack of comparison groups. We assessed the association using a continuous measure of dysmorphology severity (DS) in preschool children aged 2-5 years (322 with ASD and intellectual disability [ID], 188 with ASD without ID, and 371 without ASD from the general population [POP]). In bivariate analyses, an inverse association between DS and expressive language, receptive language, fine motor, and visual reception skills was observed in children with ASD and ID. An inverse association of DS with fine motor and visual reception skills, but not expressive language and receptive language, was found in children with ASD without ID. No associations were observed in POP children. These results persisted after exclusion of children with known genetic syndromes or major morphologic anomalies. Quantile regression models showed that the inverse relationships remained significant after adjustment for sex, race/ethnicity, maternal education, family income, study site, and preterm birth. DS was not associated with autistic traits or autism symptom severity, behaviors, or regression among children with ASD with or without ID. Thus, DS was associated with a global impairment of cognitive functioning in children with ASD and ID, but only with fine motor and visual reception deficits in children with ASD without ID. A better understanding is needed for mechanisms that explain the association between DS and cognitive impairment in children with different disorders. Autism Res 2020, 13: 1227-1238. © 2020 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: We examined whether having more dysmorphic features (DFs) was related to developmental problems among children with autism spectrum disorder (ASD) with or without intellectual disability (ID), and children without ASD from the general population (POP). Children with ASD and ID had more language, movement, and learning issues as the number of DFs increased. Children with ASD without ID had more movement and learning issues as the number of DFs increased. These relationships were not observed in the POP group. Implications are discussed.

Identifying schizophrenia patients who carry pathogenic genetic copy number variants using standard clinical assessment: retrospective cohort study

BACKGROUND

Copy number variants (CNVs) play a significant role in disease pathogenesis in a small subset of individuals with schizophrenia (~2.5%). Chromosomal microarray testing is a first-tier genetic test for many neurodevelopmental disorders. Similar testing could be useful in schizophrenia.

AIMS

To determine whether clinically identifiable phenotypic features could be used to successfully model schizophrenia-associated (SCZ-associated) CNV carrier status in a large schizophrenia cohort.

METHOD

Logistic regression and receiver operating characteristic (ROC) curves tested the accuracy of readily identifiable phenotypic features in modelling SCZ-associated CNV status in a discovery data-set of 1215 individuals with psychosis. A replication analysis was undertaken in a second psychosis data-set (n = 479).

RESULTS

In the discovery cohort, specific learning disorder (OR = 8.12; 95% CI 1.16-34.88, P = 0.012), developmental delay (OR = 5.19; 95% CI 1.58-14.76, P = 0.003) and comorbid neurodevelopmental disorder (OR = 5.87; 95% CI 1.28-19.69, P = 0.009) were significant independent variables in modelling positive carrier status for a SCZ-associated CNV, with an area under the ROC (AUROC) of 74.2% (95% CI 61.9-86.4%). A model constructed from the discovery cohort including developmental delay and comorbid neurodevelopmental disorder variables resulted in an AUROC of 83% (95% CI 52.0-100.0%) for the replication cohort.

CONCLUSIONS

These findings suggest that careful clinical history taking to document specific neurodevelopmental features may be informative in screening for individuals with schizophrenia who are at higher risk of carrying known SCZ-associated CNVs. Identification of genomic disorders in these individuals is likely to have clinical benefits similar to those demonstrated for other neurodevelopmental disorders.

Clinical versus automated assessments of morphological variants in twins with and without neurodevelopmental disorders

Physical examinations are recommended as part of a comprehensive evaluation for individuals with neurodevelopmental disorders (NDDs), such as autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder. These examinations should include assessment for morphological variants. Previous studies have shown an increase in morphological variants in individuals with NDDs, particularly ASD, and that these variants may be present in greater amounts in individuals with genetic alterations. Unfortunately, assessment for morphological variants can be subjective and time-consuming, and require a high degree of clinical expertise. Therefore, objective, automated methods of morphological assessment are desirable. This study compared the use of Face2Gene, an automated tool to explore facial morphological variants, to clinical consensus assessment, using a cohort of N = 290 twins enriched for NDDs (n = 135 with NDD diagnoses). Agreement between automated and clinical assessments were satisfactory to complete (78.3-100%). In our twin sample, individuals with NDDs did not have greater numbers of facial morphological variants when compared to those with typical development, nor when controlling for shared genetic and environmental factors within twin pairs. Common facial morphological variants in those with and without NDDs were similar and included thick upper lip vermilion, abnormality of the nasal tip, long face, and upslanted palpebral fissure. We conclude that although facial morphological variants can be assessed reliably in NDDs with automated tools like Face2Gene, clinical utility is limited when just exploring the facial region. Therefore, currently, automated assessments may best complement, rather than replace, in-person clinical assessments.

TRANSLATION, CULTURAL ADAPTATION, AND EVIDENCE OF INSTRUMENT VALIDITY FOR A MORPHOLOGICAL EXAMINATION PERFORMED IN CHILDREN WITH AUTISM SPECTRUM DISORDER

Objective:

For every 100 random children diagnosed with autism, at least 20 have morphological abnormalities, often associated with syndromes. Brazil does not have a standardized and validated instrument for morphological physical examination. This study aimed to translate into Brazilian Portuguese and culturally adapt the clinical signs described in the Autism Dysmorphology Measure, as well as validate the instrument in a sample of children with autism.

Methods:

The original instrument was translated, culturally adapted, and published in full, following traditional procedures for translation, back-translation, and terminology adaptation according to the Nomina Anatomica. The sample included 62 children from a published multicenter study, with intelligence quotient between 50–69, of both genders, with chronological age between 3–6 years. Two clinical geneticists performed the morphological physical examination, which consisted of investigating 82 characteristics assessing 12 body areas. We used Cohen’s Kappa coefficient to evaluate the agreement between the two observers.

Results:

The final version of the instrument – translated into Brazilian Portuguese and culturally adapted – showed high agreement between the two observers.

Conclusions:

The translated instrument meets all international criteria, and minor anomalies and their clinical descriptions were standardized and are recognizable for physicians not specialized in genetics.

Investigating Potential Biomarkers in Autism Spectrum Disorder

Background

Early identification and treatment of individuals with autism spectrum disorder (ASD) improves outcomes, but specific evidence needed to individualize treatment recommendations is lacking. Biomarkers that could be routinely measured within the clinical setting could potentially transform clinical care for patients with ASD. This demonstration project employed collection of biomarker data during regular autism specialty clinical visits and explored the relationship of biomarkers with clinical ASD symptoms.

Methods

Eighty-three children with ASD, aged 5–10 years, completed a multi-site feasibility study integrating the collection of biochemical (blood serotonin, urine melatonin sulfate excretion) and clinical (head circumference, dysmorphology exam, digit ratio, cognitive and behavioral function) biomarkers during routine ASD clinic visits. Parents completed a demographic survey and the Aberrant Behavior Checklist-Community. Cognitive function was determined by record review. Data analysis utilized Wilcoxon two-sample tests and Spearman correlations.

Results

Participants were 82% male, 63% White, 19% Hispanic, with a broad range of functioning. Group means indicated hyperserotonemia. In a single regression analysis adjusting for race and median household income, higher income was associated with higher levels of blood serotonin and urine melatonin sulfate excretion levels (p = 0.004 and p = 0.04, respectively). Melatonin correlated negatively with age (p = 0.048) and reported neurologic problems (p = 0.02). Dysmorphic status correlated with higher reported stereotyped behavior (p = 0.02) and inappropriate speech (p = 0.04).

Conclusion

This demonstration project employed collection of multiple biomarkers, allowed for examination of associations between biochemical and clinical measures, and identified several findings that suggest direction for future studies. This clinical research model has promise for integrative biomarker research in individuals with complex, heterogeneous neurodevelopmental disorders such as ASD.

A Novel Approach to Dysmorphology to Enhance the Phenotypic Classification of Autism Spectrum Disorder in the Study to Explore Early Development

The presence of multiple dysmorphic features in some children with autism spectrum disorder (ASD) might identify distinct ASD phenotypes and serve as potential markers for understanding causes and prognoses. To evaluate dysmorphology in ASD, children aged 3-6 years with ASD and non-ASD population controls (POP) from the Study to Explore Early Development were evaluated using a novel, systematic dysmorphology review approach. Separate analyses were conducted for non-Hispanic White, non-Hispanic Black, and Hispanic children. In each racial/ethnic group, ~ 17% of ASD cases were Dysmorphic compared with ~ 5% of POP controls. The ASD-POP differential was not explained by known genetic disorders or birth defects. In future epidemiologic studies, subgrouping ASD cases as Dysmorphic vs. Non-dysmorphic might help delineate risk factors for ASD.

The neurological examination adapted for neuropsychiatry

The neuropsychiatric examination includes standard neurological and cognitive examination techniques with several additional observations and tasks designed to capture abnormalities common among patients with neuropsychiatric disorders or neurocognitive complaints. Although useful as a screening tool, a single standardized rating scale such as the Mini Mental State Examination (MMSE) or the Montreal Cognitive Assessment (MoCA) is insufficient to establish a neuropsychiatric diagnosis. Extra attention is paid to findings commonly seen in the setting of psychiatric disorders, dementias, movement disorders, or dysfunction of cortical or subcortical structures. Dysmorphic features, dermatologic findings, neurodevelopmental signs, signs of embellishment, and expanded neurocognitive testing are included. The neuropsychiatric clinician utilizes the techniques described in this article to adapt the examination to each patient's situation, choosing the most appropriate techniques to supplement the basic neurological and psychiatric examinations in support of diagnostic hypotheses being considered. The added examination techniques facilitate diagnosis of neurocognitive disorders and enable neuropsychiatric formulation.

Heritable genotype contrast mining reveals novel gene associations specific to autism subgroups

Though the genetic etiology of autism is complex, our understanding can be improved by identifying genes and gene-gene interactions that contribute to the development of specific autism subtypes. Identifying such gene groupings will allow individuals to be diagnosed and treated according to their precise characteristics. To this end, we developed a method to associate gene combinations with groups with shared autism traits, targeting genetic elements that distinguish patient populations with opposing phenotypes. Our computational method prioritizes genetic variants for genome-wide association, then utilizes Frequent Pattern Mining to highlight potential interactions between variants. We introduce a novel genotype assessment metric, the Unique Inherited Combination support, which accounts for inheritance patterns observed in the nuclear family while estimating the impact of genetic variation on phenotype manifestation at the individual level. High-contrast variant combinations are tested for significant subgroup associations. We apply this method by contrasting autism subgroups defined by severe or mild manifestations of a phenotype. Significant associations connected 286 genes to the subgroups, including 193 novel autism candidates. 71 pairs of genes have joint associations with subgroups, presenting opportunities to investigate interacting functions. This study analyzed 12 autism subgroups, but our informatics method can explore other meaningful divisions of autism patients, and can further be applied to reveal precise genetic associations within other phenotypically heterogeneous disorders, such as Alzheimer's disease.

Minor physical anomalies in neurodevelopmental disorders: a twin study

BACKGROUND

Minor physical anomalies (MPAs) are subtle anatomical deviations in one's appearance and may suggest altered embryogenesis. MPAs have been shown to be more common in neurodevelopmental disorders (NDDs) compared with typical development. Still, further studies are needed on MPAs in NDDs, especially using twins to adjust for confounding familial factors.

METHODS

Clinical assessments were conducted on 116 twins (61 NDD, 55 controls) from 51 monozygotic and 7 dizygotic pairs to examine MPAs and their association with DSM-5 defined NDDs. Additionally, the relationship between the number of MPAs within twins by zygosity was investigated.

RESULTS

Within the cohort sample, a specific association was found between MPAs and autism spectrum disorder (ASD) diagnosis (crude odds ratio = 1.29, p = .047; adjusted odds ratios = 1.26-1.33, adjusted p values = .032-.073) and autistic traits (crude β = 3.02, p = .002; adjusted β = 2.28, p = .019), but not NDDs in general or ADHD, nor within-pairs. Identified MPAs in ASD included overweight, hypermobility, pes planus, straight eyebrows, vision impairment, arachnodactyly/long toes, long eyelashes, and microtia. The number of MPAs within all monozygotic pairs was highly correlated (r = .88, p < .001).

CONCLUSION

MPAs are more frequent in participants with ASD and may be influenced by genetics. The value of MPAs for (early) detection should be further explored, as they might index individuals at increased risk for ASD in particular.

Determining the frequency of morphological characteristics in a sample of Brazilian children

OBJECTIVE

To establish the frequency of 82 morphological features in a sample of Brazilian children (between 3 and 13 years old), to understand the influence of age, gender, and ethnicity.

METHODS

This was a cross-sectional study that evaluated 239 children with typical development (between 3 and 13 years old) regarding the presence of 82 morphological characteristics. A previously described protocol, based on the London Dysmorphology Database, was applied to evaluate the sample. This protocol was culturally adapted to Brazilian Portuguese.

RESULTS

The frequency of 82 morphological characteristics was established in the sample; of 82 characteristics, 50% were considered morphological anomalies (frequency less than 4%). At least 25% of the sample presented more than one minor morphological anomaly. Age was shown to influence the frequency of the following morphological characteristics: widow's peak, prominent antihelix, prominent upper lip, irregular or crowded teeth, and clinodactyly, but had no influence on the frequency of minor morphological anomalies. Gender influenced dysplastic ears and attached earlobe, but had no influence on the frequency of minor morphological anomalies; ethnicity showed influence on camptodactyly and prominent antihelix. A statistically significant divergence was observed regarding 43 of the 73 morphological characteristics that could be compared with literature data (58.9%).

CONCLUSIONS

The study determined the frequency of 82 morphological characteristics in 239 children with typical development. Age was the variable that showed more influence on the frequency of morphological characteristics, and comparison with literature data showed that the frequency depends on variables such as age and ethnicity.

Feasibility of Conducting Autism Biomarker Research in the Clinical Setting

OBJECTIVE

Recruitment and completion of research activities during regular clinical care has the potential to increase research participation in complex neurodevelopmental disorders. We evaluated the feasibility, and effect on clinical care, of conducting biomarker research within a subspecialty clinical visit for autism spectrum disorder (ASD).

METHODS

Children, aged 5 to 10 years, were recruited by providers in ASD clinics at 5 institutions. Biomarkers collected were growth measurements, head circumference, neurologic and dysmorphology examinations, digit ratio (2D:4D) measurement, and platelet serotonin and urinary melatonin sulfate excretion levels. Parents completed the Aberrant Behavior Checklist-Community and a medical/demographic questionnaire. Cognitive level was abstracted from the medical record. Parents and clinicians completed surveys on the effect of the study on the clinical visit.

RESULTS

Eighty-three children and their caregivers participated. Factors limiting participation included difficulty reaching families by phone and parent concern about the study blood draw requirement. All children completed at least 4 of 7 planned research activities. Demographic factors, educational placement, and child behavior were not associated with completion of study activities. Lower nonverbal cognitive function was weakly associated with fewer activities completed. Forty-four percent of clinicians reported an effect of the research study on the clinical visit. However, neither parent-reported nor clinician-reported effect was associated with the degree of study activity completion.

CONCLUSION

Recruiting study participants in the context of scheduled ASD clinical visits required significant effort. However, once recruited, participants completed most study activities, regardless of behavioral symptom severity. Research activities did not adversely affect the clinical visit.

Developmental functioning and medical Co-morbidity profile of children with complex and essential autism

Children with Autism Spectrum Disorders (ASD) may be characterized as "complex" (those with microcephaly and/or dysmorphology) or "essential" (those with neither of these two). Previous studies found subjects in the complex group exhibited lower IQ scores, poorer response to behavioral intervention, more seizures and more abnormal EEGs and brain MRIs compared to the essential group. The objective of this study was to determine if there are differences in complex versus essential subjects based on several developmental/psychological measures as well as certain medical comorbidities. This study utilized data from 1,347 individuals (2-17 years old) well-characterized subjects enrolled in Autism Treatment Network (ATN) Registry. Head circumference measurement and the Autism Dysmorphology Measure (ADM) were used by trained physicians to classify subjects as complex or essential. Significantly lower scores were seen for complex subjects in cognitive level, adaptive behavior and quality of life. Complex subjects showed significantly increased physician-documented GI symptoms and were on a higher number of medications. No significant differences in autism severity scores, behavioral ratings and parent-reported sleep problems were found. After adjusting for multiple comparisons made, adaptive scores remained significantly lower for the complex group, and the complex group used a significantly higher number of medications and had increased GI symptoms. Complex and essential autism subtypes may have distinct developmental and medical correlates and thus underlines the importance of looking for microcephaly and dysmorphology, when evaluating a child with autism. Determining this distinction in autism may have implications in prognosis, identifying medical co-morbidities, directing diagnostic evaluations and treatment interventions. Autism Res 2017, 10: 1344-1352. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

Integrative Variation Analysis Reveals that a Complex Genotype May Specify Phenotype in Siblings with Syndromic Autism Spectrum Disorder

It has been proposed that copy number variations (CNVs) are associated with increased risk of autism spectrum disorder (ASD) and, in conjunction with other genetic changes, contribute to the heterogeneity of ASD phenotypes. Array comparative genomic hybridization (aCGH) and exome sequencing, together with systems genetics and network analyses, are being used as tools for the study of complex disorders of unknown etiology, especially those characterized by significant genetic and phenotypic heterogeneity. Therefore, to characterize the complex genotype-phenotype relationship, we performed aCGH and sequenced the exomes of two affected siblings with ASD symptoms, dysmorphic features, and intellectual disability, searching for de novo CNVs, as well as for de novo and rare inherited point variations—single nucleotide variants (SNVs) or small insertions and deletions (indels)—with probable functional impacts. With aCGH, we identified, in both siblings, a duplication in the 4p16.3 region and a deletion at 8p23.3, inherited by a paternal balanced translocation, t(4, 8) (p16; p23). Exome variant analysis found a total of 316 variants, of which 102 were shared by both siblings, 128 were in the male sibling exome data, and 86 were in the female exome data. Our integrative network analysis showed that the siblings’ shared translocation could explain their similar syndromic phenotype, including overgrowth, macrocephaly, and intellectual disability. However, exome data aggregate genes to those already connected from their translocation, which are important to the robustness of the network and contribute to the understanding of the broader spectrum of psychiatric symptoms. This study shows the importance of using an integrative approach to explore genotype-phenotype variability.

Head circumference and brain size in autism spectrum disorder: A systematic review and meta-analysis

Macrocephaly and brain overgrowth have been associated with autism spectrum disorder. We performed a systematic review and meta-analysis to provide an overall estimate of effect size and statistical significance for both head circumference and total brain volume in autism. Our literature search strategy identified 261 and 391 records, respectively; 27 studies defining percentages of macrocephalic patients and 44 structural brain imaging studies providing total brain volumes for patients and controls were included in our meta-analyses. Head circumference was significantly larger in autistic compared to control individuals, with 822/5225 (15.7%) autistic individuals displaying macrocephaly. Structural brain imaging studies measuring brain volume estimated effect size. The effect size is higher in low functioning autistics compared to high functioning and ASD individuals. Brain overgrowth was recorded in 142/1558 (9.1%) autistic patients. Finally, we found a significant interaction between age and total brain volume, resulting in larger head circumference and brain size during early childhood. Our results provide conclusive effect sizes and prevalence rates for macrocephaly and brain overgrowth in autism, confirm the variation of abnormal brain growth with age, and support the inclusion of this endophenotype in multi-biomarker diagnostic panels for clinical use.

Overweight and Obesity in a Sample of Children With Autism Spectrum Disorder

OBJECTIVE

To determine the prevalence of overweight/obese status in children with autism spectrum disorders (ASD), identify associated characteristics, and develop a model to predict weight status.

METHODS

The prevalence of overweight and obesity was determined in 2769 children with ASD enrolled in the Autism Speaks Autism Treatment Network, a collaboration of 17 academic centers, and compared with a national sample matched for age, sex, and race. Associations in the ASD sample between weight status and demographic and clinical variables, such as age, race, head circumference, and adaptive functioning, were tested using ordinal logistic regression. The accuracy of a final model that predicted weight status based on early life variables was evaluated in a validation sample.

RESULTS

The prevalence of overweight and obesity were 33.9% and 18.2%, respectively; ASD was associated with a higher risk of obesity (but not overweight) relative to the national sample (odds ratio [OR], 1.16; 95% confidence interval [CI], 1.05-1.28; P = .003). In the adjusted analysis, overweight/obese status was significantly associated with Hispanic ethnicity (OR, 1.99; 95% CI, 1.37-2.89), parental high school education (OR, 1.56; 95% CI, 1.09-2.21), high birth weight (OR, 1.56; 95% CI, 1.11-2.18), macrocephaly (OR, 4.01; 95% CI, 2.96-5.43), and increased somatic symptoms (OR, 1.41; 95% CI, 1.01-1.95). A prediction model designed to have high sensitivity predicted low risk of overweight/obesity accurately, but had low positive predictive value.

CONCLUSIONS

The prevalence of obesity in children with ASD was greater than a national sample. Independent associations with increased weight status included known risk factors and macrocephaly and increased level of somatic symptoms. A model based on early life variables accurately predicted low risk of overweight/obesity.

Use of dysmorphology for subgroup classification on autism spectrum disorder in Chinese children

Data from 1,261 Chinese Autistic Spectrum Disorder (ASD) patients were evaluated and categorized into dysmorphic (10.79 %) and non-dysmorphic groups (89.21 %) upon physical examination by the presence of dysmorphic features. Abnormal MRI/CT result, IQ scores and epilepsy were significantly associated with the dysmorphic group of ASD children. However, gender, EEG abnormality and family history and recurrence of ASD were not found to be significantly different between group statuses. It is suggested that results collected from the Chinese population generally resembles that found in the Caucasians with ethnical differences still present. Current study supports the result shown in Miles' study (Miles et al. in Am J Med Genet 135A:171-180, 2005), in which heterogeneity subtypes of autism of different genetic origins which could be distinguished by presence of dysmorphic features on the patients.

Predictive value of morphological features in patients with autism versus normal controls

We investigated the predictive power of morphological features in 224 autistic patients and 224 matched-pairs controls. To assess the relationship between the morphological features and autism, we used the receiver operator curves (ROC). In addition, we used recursive partitioning (RP) to determine a specific pattern of abnormalities that is characteristic for the difference between autistic children and typically developing controls. The present findings showed that morphological features are significantly increased in patients with autism. Using ROC and RP, some of the morphological measures also led to strong predictive accuracy. Facial asymmetry, multiple hair whorls and prominent forehead significantly differentiated patients with autism from controls. Future research on multivariable risk prediction models may benefit from the use of morphological features.

Biochemical screening and PTEN mutation analysis in individuals with autism spectrum disorders and macrocephaly

Unlike some other childhood neurodevelopmental disorders, no diagnostic biochemical marker has been identified in all individuals with an autism spectrum disorder (ASD). This deficit likely results from genetic heterogeneity among the population. Therefore, we evaluated a subset of individuals with ASDs, specifically, individuals with or without macrocephaly in the presence or absence of PTEN mutations. We sought to determine if amino or organic acid markers could be used to identify individuals with ASDs with or without macrocephaly in the presence or absence of PTEN mutations, and to establish the degree of macrocephaly in individuals with ASDs and PTEN mutation. Urine, blood and occipital-frontal circumference (OFC) measurements were collected from 69 individuals meeting DSM-IV-TR criteria. Urine and plasma samples were subjected to amino and organic acid analyses. PTEN was Sanger-sequenced from germline genomic DNA. Germline PTEN mutations were identified in 27% (6/22) of the macrocephalic ASD population. All six PTEN mutation-positive individuals were macrocephalic with average OFC+4.35 standard deviations (SDs) above the mean. No common biochemical abnormalities were identified in macrocephalic ASD individuals with or without PTEN mutations. In contrast, among the collective ASD population, elevation of urine aspartic acid (87%; 54/62), plasma taurine (69%; 46/67) and reduction of plasma cystine (72%; 46/64) were observed. PTEN sequencing should be carried out for all individuals with ASDs and macrocephaly with OFC ≥2SDs above the mean. A proportion of individuals with ASDs may have an underlying disorder in sulfur amino acid metabolism.

Determinants of maternal satisfaction with diagnosis disclosure of autism

BACKGROUND/PURPOSE

Diagnosis disclosure is an important clinical issue in developmental disabilities, which may influence parents' ability to cope with their child's conditions. This paper presents the content and patterns of diagnosis-informed counseling for mothers of children with autism and investigates the determinants for maternal satisfaction with this counseling, in order to improve clinical practice.

METHODS

Mothers of 151 children, aged 3-12 years, with DSM-IV autistic disorder, confirmed by the Chinese version of the Autism Diagnostic Interview-Revised, were assessed. We collected information about the mothers' experience with diagnosis-informed counseling, their personality characteristics, and the extent to which they were satisfied with the counseling.

RESULTS

Satisfaction with diagnosis-informed counseling was related more to the context of the counseling, including the attitude of the counselors and the timing and duration of counseling, than to its content. Parents' social desirability, educational level, and employment status were negatively associated with their satisfaction with counseling. However, immediate emotion, neuroticism, and extroversion did not have a significant effect on the satisfaction with counseling. Approximately 60% of the mothers preferred to be informed of having an autistic child after the diagnosis had been confirmed.

CONCLUSION

Our findings suggest that more efforts are needed to improve the quality of diagnosis-informed counseling in autism, particularly in the context of breaking the news to mothers of children with autism. Future study could further examine the moderating effect of diagnostic subtype of autism spectrum disorders, treatment response, or social support on maternal satisfaction with diagnosis-informed counseling (ClinicalTrials.gov number, NCT00494754).

A common X-linked inborn error of carnitine biosynthesis may be a risk factor for nondysmorphic autism

We recently reported a deletion of exon 2 of the trimethyllysine hydroxylase epsilon (TMLHE) gene in a proband with autism. TMLHE maps to the X chromosome and encodes the first enzyme in carnitine biosynthesis, 6-N-trimethyllysine dioxygenase. Deletion of exon 2 of TMLHE causes enzyme deficiency, resulting in increased substrate concentration (6-N-trimethyllysine) and decreased product levels (3-hydroxy-6-N-trimethyllysine and γ-butyrobetaine) in plasma and urine. TMLHE deficiency is common in control males (24 in 8,787 or 1 in 366) and was not significantly increased in frequency in probands from simplex autism families (9 in 2,904 or 1 in 323). However, it was 2.82-fold more frequent in probands from male-male multiplex autism families compared with controls (7 in 909 or 1 in 130; P = 0.023). Additionally, six of seven autistic male siblings of probands in male-male multiplex families had the deletion, suggesting that TMLHE deficiency is a risk factor for autism (metaanalysis Z-score = 2.90 and P = 0.0037), although with low penetrance (2-4%). These data suggest that dysregulation of carnitine metabolism may be important in nondysmorphic autism; that abnormalities of carnitine intake, loss, transport, or synthesis may be important in a larger fraction of nondysmorphic autism cases; and that the carnitine pathway may provide a novel target for therapy or prevention of autism.

Minor physical anomalies in children with autism spectrum disorders

OBJECTIVE

There is clinical heterogeneity among the autism spectrum disorders (ASD). The presence of dysmorphology (minor physical anomalies; MPAs) is one possible tool for defining a clinically relevant subset in ASD. This study employs an adaptation of Miles and Hillman's (2000) classifications by using photographs to identify a subgroup with significant dysmorphology among children with ASD, typical development (TYP), and developmental delay (DD).

METHOD

Children with ASD, DD, and TYP between 2 and 5 years old were part of the CHARGE Study. Pediatric specialists blinded to diagnostic group classified photographs based on the number of MPAs present: 'dysmorphic' if >3 and 'nondysmorphic' if <3 MPAs.

RESULTS

Photographs for 324 children were included. Significantly more children with ASD were classified as dysmorphic compared to TYP children (p = .007). In children with ASD, seizures were more prevalent in those rated dysmorphic (p = .005). Frequencies were similar between ASD versus DD (p = .19) after removing those with known syndromes.

CONCLUSION

Photographic assessment can be used to detect generalized dysmorphology in children who are often difficult to examine. This has clinical relevance, as children with multiple MPAs can be identified through the use of photographs and prioritized for investigation of brain abnormalities and underlying genetic disorders.

The speech aversion hypothesis has explanatory power in a Minimal Speech Approach to aloof, non-verbal, severe autism

In the search for 'pure autism', non-verbal children labeled aloof, Severely Autistic with Developmental Disabilities (ASA/DD), are routinely excluded from psychological research. This exclusion is predicated on the claim that they are indistinguishable from those with SLD/PMLD, which is refuted through a discussion of the extant literature. A novel, falsifiable, speech aversion hypothesis is proposed: "aloof, non-verbal young children (<7 years), with severe autism (CARS≥37), but without significant dysmorphic features, will show aversive reactions to complex speech (>2-3 words), but not to a silent interlocutor, or one imitating their vocalizations, in proximal encounters." Implications are examined by deconstructing the presenting symptoms of ASA/DD in response to the hypothesis. Supporting evidence is drawn from: Minimal Speech Approach (MSA) research showing high levels of spontaneous requests for social routines; a reinterpretation of still-face research as a still-(silent)-face paradigm; auditory processing MMN data employing EEG/MEG; and possible links to epileptiform activity and verbal auditory agnosia. Guidelines are established for future research. This hypothesis, if corroborated, would add to the auditory processing anomalies seen in severe autism and lead to synergies of existing and new areas of research, with significant theoretical, therapeutic, and educational implications.

Facial phenotypes in subgroups of prepubertal boys with autism spectrum disorders are correlated with clinical phenotypes

BACKGROUND

The brain develops in concert and in coordination with the developing facial tissues, with each influencing the development of the other and sharing genetic signaling pathways. Autism spectrum disorders (ASDs) result from alterations in the embryological brain, suggesting that the development of the faces of children with ASD may result in subtle facial differences compared to typically developing children. In this study, we tested two hypotheses. First, we asked whether children with ASD display a subtle but distinct facial phenotype compared to typically developing children. Second, we sought to determine whether there are subgroups of facial phenotypes within the population of children with ASD that denote biologically discrete subgroups.

METHODS

The 3dMD cranial System was used to acquire three-dimensional stereophotogrammetric images for our study sample of 8- to 12-year-old boys diagnosed with essential ASD (n = 65) and typically developing boys (n = 41) following approved Institutional Review Board protocols. Three-dimensional coordinates were recorded for 17 facial anthropometric landmarks using the 3dMD Patient software. Statistical comparisons of facial phenotypes were completed using Euclidean Distance Matrix Analysis and Principal Coordinates Analysis. Data representing clinical and behavioral traits were statistically compared among groups by using χ2 tests, Fisher's exact tests, Kolmogorov-Smirnov tests and Student's t-tests where appropriate.

RESULTS

First, we found that there are significant differences in facial morphology in boys with ASD compared to typically developing boys. Second, we also found two subgroups of boys with ASD with facial morphology that differed from the majority of the boys with ASD and the typically developing boys. Furthermore, membership in each of these distinct subgroups was correlated with particular clinical and behavioral traits.

CONCLUSIONS

Boys with ASD display a facial phenotype distinct from that of typically developing boys, which may reflect alterations in the prenatal development of the brain. Subgroups of boys with ASD defined by distinct facial morphologies correlated with clinical and behavioral traits, suggesting potentially different etiologies and genetic differences compared to the larger group of boys with ASD. Further investigations into genes involved in neurodevelopment and craniofacial development of these subgroups will help to elucidate the causes and significance of these subtle facial differences.

Craniofacial dysmorphism and developmental disorders among children with chromosomal microdeletions and duplications of unknown significance

OBJECTIVE

Microarray comparative genomic hybridization is an extremely sensitive technology that increasingly identifies deletions and duplications of unknown significance. Our objective was to determine whether children with autism and other developmental delays who have genomic imbalances manifest more craniofacial dysmorphism and have lower cognitive scores than children from the same clinic population who have normal microarrays.

METHOD

A clinical geneticist, blinded to the history, reviewed photographs for craniofacial dysmorphism. Forty-five (24%) of 187 children who had a microarray had a deletion or duplication >200 kb. Thirty-six of those with abnormal microarrays (11 microdeletions and 25 duplications) had completed their evaluation, which included 3 deletions and 10 duplications of unknown significance. Subjects with and without microarray anomalies did not differ in age, sex, growth parameters, parental age or education level, insurance status, or cognitive scores.

RESULTS

Twenty-eight (78%) of the 36 children with microarray anomalies had craniofacial dysmorphism as compared with 45% of those with normal microarrays (p = .0005). Among the 13 children with microarray abnormalities of unknown significance, 10 (77%) were dysmorphic, similar to 18 (78%) of 23 who had a genomic imbalance known to affect development. Among the 10 children with dysmorphism and a microarray anomaly of unknown significance, 7 also had an IQ ≤70 and/or a diagnosis of autism.

CONCLUSION

Microdeletions and duplications not previously known to be associated with human disease were strongly associated with craniofacial dysmorphism, cognitive scores ≤70, and a diagnosis of autism in this clinic population, providing presumptive evidence that these genomic imbalances are clinically significant.

Use of array CGH to detect exonic copy number variants throughout the genome in autism families detects a novel deletion in TMLHE

Autism is a neurodevelopmental disorder with increasing evidence of heterogeneous genetic etiology including de novo and inherited copy number variants (CNVs). We performed array comparative genomic hybridization using a custom Agilent 1 M oligonucleotide array intended to cover 197 332 unique exons in RefSeq genes; 98% were covered by at least one probe and 95% were covered by three or more probes with the focus on detecting relatively small CNVs that would implicate a single protein-coding gene. The study group included 99 trios from the Simons Simplex Collection. The analysis identified and validated 55 potentially pathogenic CNVs, categorized as de novo autosomal heterozygous, inherited homozygous autosomal, complex autosomal and hemizygous deletions on the X chromosome of probands. Twenty percent (11 of 55) of these CNV calls were rare when compared with the Database of Genomic Variants. Thirty-six percent (20 of 55) of the CNVs were also detected in the same samples in an independent analysis using the 1 M Illumina single-nucleotide polymorphism array. Findings of note included a common and sometimes homozygous 61 bp exonic deletion in SLC38A10, three CNVs found in lymphoblast-derived DNA but not present in whole-blood derived DNA and, most importantly, in a male proband, an exonic deletion of the TMLHE (trimethyllysine hydroxylase epsilon) that encodes the first enzyme in the biosynthesis of carnitine. Data for CNVs present in lymphoblasts but absent in fresh blood DNA suggest that these represent clonal outgrowth of individual B cells with pre-existing somatic mutations rather than artifacts arising in cell culture. GEO accession number GSE23765 (http://www.ncbi.nlm.nih.gov/geo/, date last accessed on 30 August 2011). Genboree accession: http://genboree.org/java-bin/gbrowser.jsp?refSeqId=1868&entryPointId=chr17&from=53496072&to=53694382&isPublic=yes, date last accessed on 30 August 2011.

Autism spectrum disorders--a genetics review

Autism is an etiologically and clinically heterogeneous group of disorders, diagnosed solely by the complex behavioral phenotype. On the basis of the high-heritability index, geneticists are confident that autism will be the first behavioral disorder for which the genetic basis can be well established. Although it was initially assumed that major genome-wide and candidate gene association studies would lead most directly to common autism genes, progress has been slow. Rather, most discoveries have come from studies of known genetic disorders associated with the behavioral phenotype. New technology, especially array chromosomal genomic hybridization, has both increased the identification of putative autism genes and raised to approximately 25%, the percentage of children for whom an autism-related genetic change can be identified. Incorporating clinical geneticists into the diagnostic and autism research arenas is vital to the field. Interpreting this new technology and deciphering autism's genetic montage require the skill set of the clinical geneticist including knowing how to acquire and interpret family pedigrees, how to analyze complex morphologic, neurologic, and medical phenotypes, sorting out heterogeneity, developing rational genetic models, and designing studies. The current emphasis on deciphering autism spectrum disorders has accelerated the field of neuroscience and demonstrated the necessity of multidisciplinary research that must include clinical geneticists both in the clinics and in the design and implementation of basic, clinical, and translational research.

Morphological features in children with autism spectrum disorders: a matched case-control study

This study was designed to examine morphological features in a large group of children with autism spectrum disorder versus normal controls. Amongst 421 patients and 1,007 controls, 224 matched pairs were created. Prevalence rates and odds ratios were analyzed by conditional regression analysis, McNemar test or paired t-test matched pairs. Morphological abnormalities were significantly more prevalent in patients with autism than in the normal control group and 48 morphological features distinguished patients from controls. Our findings show that morphological features are associated with autism. Exploring potential underlying genetic mechanisms of this association might lead to a better understanding of autism.

Medical conditions in autism spectrum disorders

Autism spectrum disorder (ASD) is a behaviourally defined syndrome where the etiology and pathophysiology is only partially understood. In a small proportion of children with the condition, a specific medical disorder is identified, but the causal significance in many instances is unclear. Currently, the medical conditions that are best established as probable causes of ASD include Fragile X syndrome, Tuberous Sclerosis and abnormalities of chromosome 15 involving the 15q11-13 region. Various other single gene mutations, genetic syndromes, chromosomal abnormalities and rare de novo copy number variants have been reported as being possibly implicated in etiology, as have several ante and post natal exposures and complications. However, in most instances the evidence base for an association with ASD is very limited and largely derives from case reports or findings from small, highly selected and uncontrolled case series. Not only therefore, is there uncertainty over whether the condition is associated, but the potential basis for the association is very poorly understood. In some cases the medical condition may be a consequence of autism or simply represent an associated feature deriving from an underlying shared etiology. Nevertheless, it is clear that in a growing proportion of individuals potentially causal medical conditions are being identified and clarification of their role in etio-pathogenesis is necessary. Indeed, investigations into the causal mechanisms underlying the association between conditions such as tuberous sclerosis, Fragile X and chromosome 15 abnormalities are beginning to cast light on the molecular and neurobiological pathways involved in the pathophysiology of ASD. It is evident therefore, that much can be learnt from the study of probably causal medical disorders as they represent simpler and more tractable model systems in which to investigate causal mechanisms. Recent advances in genetics, molecular and systems biology and neuroscience now mean that there are unparalleled opportunities to test causal hypotheses and gain fundamental insights into the nature of autism and its development.

Role of the dysmorphologic evaluation in the child with developmental delay

This article focuses on the dysmorphologic evaluation of the child who has developmental delay or cognitive impairment. Attention is focused on minor anomalies, because those are often considered to be the dysmorphic features that are the component manifestations of a particular syndrome. This article provides a brief discussion of craniofacial, skin, and limb anomalies (which are more likely to be noted not only by clinicians but also by allied health workers) and notes which features are particularly helpful clues to common syndromes, metabolic disorders, or autism syndromes.