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Table 1 Key features of the EMA study

From: A profile and review of findings from the Early Markers for Autism study: unique contributions from a population-based case–control study in California

Feature Benefit for autism epidemiologic study
Population-based Avoids biases due to selected clinical samples
Improves generalizability to source populations
Capitalizes on existing resources (DDS, Vital Statistics, CBP) Enables relatively large sample size
Enables prospective examination of biomarkers through use of archived biospecimens
Efficient design- no participant re-contact required
Multiple comparison groups (GP, ID)a Enables consideration of specificity of associations to ASD (ASD vs GP) vs broader developmental delays (ID vs GP and ASD vs ID comparisons)
Inclusion of biospecimens collected during critical developmental periods prior to diagnosis Allows for measurement of exposure levels during mid-pregnancy or in newborn period, rather than estimation via reported or recalled information
Availability of a wide range of biomarkers (see Table 3)
Case confirmation via clinician review of records Enhances confidence in validity of diagnostic categories under study
Reduces potential for outcome misclassification
Rich dataset of multiple exposures/biomarkers Allows for examination of combined effects
Ability to examine mechanisms through pathway analyses considering intermediate biomarkers (e.g., thyroid hormones, immune markers as intermediates between EDCs and outcomes)
Interdisciplinary team Supports cross-cutting science
Early stage investigator engagement and mentorship supportedb
  1. ASD autism spectrum disorder, CBP California Biobank Program, DDS Department of Developmental Services, EDCs endocrine-disrupting chemicals, GP general population controls, ID intellectual disability
  2. aThe EMA study also included a small number of siblings (67 siblings of those with ASD and 65 of those with ID) to enable additional within-family sibling comparisons; however, these have not been utilized in studies summarized here to date
  3. bOver 70% of EMA publications to date have been led by early stage investigators, often stimulating career development