Distributional Properties and Criterion Validity of a Shortened Version of the Social Responsiveness Scale: Results from the ECHO Program and Implications for Social Communication Research

Prior work proposed a shortened version of the Social Responsiveness Scale (SRS), a commonly used quantitative measure of social communication traits. We used data from 3031 participants (including 190 ASD cases) from the Environmental Influences on Child Health Outcomes (ECHO) Program to compare distributional properties and criterion validity of 16-item “short” to 65-item “full” SRS scores. Results demonstrated highly overlapping distributions of short and full scores. Both scores separated case from non-case individuals by approximately two standard deviations. ASD prediction was nearly identical for short and full scores (area under the curve values of 0.87, 0.86 respectively). Findings support comparability of shortened and full scores, suggesting opportunities to increase efficiency. Future work should confirm additional psychometric properties of short scores.

     

Association between pica and gastrointestinal symptoms in preschoolers with and without autism spectrum disorder: Study to Explore Early Development

BackgroundPica, the repeated ingestion of nonfood items, can result in gastrointestinal (GI) outcomes. Children with autism spectrum disorder (ASD) and other developmental disabilities (DDs) are disproportionately affected by both pica and GI symptoms. Study of the inter-relationship between pica, GI symptoms, and ASD/DD is limited.Objective/HypothesisWe assessed associations between pica and GI symptoms in preschool-aged children with and without ASD and other (non-ASD) DDs in the Study to Explore Early Development.MethodsOur sample included children with ASD (n = 1244), other DDs (n = 1593), and population (POP) controls (n = 1487). Data to define final case-control status, pica, and GI symptoms were from standardized developmental assessments/questionnaires. Prevalence ratios, adjusted for sociodemographic factors (aPRs), and 95% confidence intervals were derived from modified Poisson regression.ResultsWithin each group (ASD, DD, POP) and for the total sample, pica was associated with vomiting (aPR for total sample 2.6 [1.7, 4.0]), diarrhea (1.8 [1.4, 2.2]), and loose stools (1.8 [1.4, 2.2]). In the DD group, pica was associated with constipation (1.4 [1.03, 1.9]) and pain on stooling (1.8 [1.2, 2.6]). In analyses of the subgroup without pica, increases in GI symptoms were still evident in the ASD and DD groups compared to POP group.ConclusionThese findings highlight an important adverse effect of pica, GI symptoms, in children with and without ASD and DDs; nonetheless, pica does not fully explain the increased risk for GI symptoms among children with ASD and DDs. These findings inform the specialized healthcare needs of children with ASD and other DDs.     

SNP-specific array-based allele-specific expression analysis

We have developed an optimized array-based approach for customizable allele-specific gene expression (ASE) analysis. The central features of the approach are the ability to select SNPs at will for detection, and the absence of need to PCR amplify the target. A surprisingly long probe length (39-49 nt) was needed for allelic discrimination. Reconstitution experiments demonstrate linearity of ASE over a broad range. Using this approach, we have discovered at least two novel imprinted genes, NLRP2, which encodes a member of the inflammasome, and OSBPL1A, which encodes a presumed oxysterol-binding protein, were both preferentially expressed from the maternal allele. In contrast, ERAP2, which encodes an aminopeptidase, did not show preferential parent-of-origin expression, but rather, cis-acting nonimprinted differential allelic control. The approach is scalable to the whole genome and can be used for discovery of functional epigenetic modifications in patient samples.     

Comprehensive high-throughput arrays for relative methylation (CHARM)

This study was originally conceived to test in a rigorous way the specificity of three major approaches to high-throughput array-based DNA methylation analysis: (1) MeDIP, or methylated DNA immunoprecipitation, an example of antibody-mediated methyl-specific fractionation; (2) HELP, or HpaII tiny fragment enrichment by ligation-mediated PCR, an example of differential amplification of methylated DNA; and (3) fractionation by McrBC, an enzyme that cuts most methylated DNA. These results were validated using 1466 Illumina methylation probes on the GoldenGate methylation assay and further resolved discrepancies among the methods through quantitative methylation pyrosequencing analysis. While all three methods provide useful information, there were significant limitations to each, specifically bias toward CpG islands in MeDIP, relatively incomplete coverage in HELP, and location imprecision in McrBC. However, we found that with an original array design strategy using tiling arrays and statistical procedures that average information from neighboring genomic locations, much improved specificity and sensitivity could be achieved, e.g., approximately 100% sensitivity at 90% specificity with McrBC. We term this approach "comprehensive high-throughput arrays for relative methylation" (CHARM). While this approach was applied to McrBC analysis, the array design and computational algorithms are fractionation method-independent and make this a simple, general, relatively inexpensive tool suitable for genome-wide analysis, and in which individual samples can be assayed reliably at very high density, allowing locus-level genome-wide epigenetic discrimination of individuals, not just groups of samples. Furthermore, unlike the other approaches, CHARM is highly quantitative, a substantial advantage in application to the study of human disease.