Stratification based on language-related endophenotypes in autism: attempt to replicate reported linkage
Sarah J Spence1, Rita M Cantor, Lien Chung
1Department of Psychiatry and Biobehavioral Sciences, University of California at Los Angeles, Los Angeles, California 90095, USA.
Summary
Stratifying autism families by language delay endophenotypes showed nominal linkage signals in several regions, suggesting this approach may reduce heterogeneity. However, larger sample sizes are needed for replication and confirmation of autism susceptibility genes.
Area of Science:
- Genetics
- Neuroscience
- Developmental Disorders
Background:
- Autism susceptibility gene identification is challenging due to significant phenotypic heterogeneity.
- Endophenotypes, particularly language-related ones, show promise in reducing this heterogeneity and pinpointing autism-related regions.
- Previous studies suggest language delay as a potential endophenotype for autism.
Purpose of the Study:
- To investigate the utility of language-related endophenotypes in autism linkage analysis.
- To determine if stratifying families by speech delay (phrase and word delay) improves the identification of autism susceptibility loci.
- To assess the impact of parental phenotype information on linkage findings.
Main Methods:
- Whole genome scan utilizing a multipoint non-parametric linkage (NPL) approach.
- Analysis of 133 multiplex autism families stratified by phrase speech delay and word delay (WD).
- Inclusion of parental phenotype data for language delay to evaluate its effect on linkage results.
Main Results:
- No chromosomal regions met genome-wide or replication significance thresholds.
- Nominal linkage signals were observed on chromosomes 1, 2, 4, 6, 7, 8, 9, 10, 12, 15, and 19 in delayed speech groups.
- Linkage findings for chromosomes 7 and 13, previously associated with language delay, were not supported. Parental phenotype data did not significantly alter linkage outcomes.
Conclusions:
- Language delay endophenotype stratification shows potential for reducing heterogeneity in autism genetics studies.
- The observed nominal linkage signals warrant further investigation with larger sample sizes.
- Increased sample sizes are crucial for achieving adequate statistical power to replicate findings and confirm autism susceptibility loci.
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