Functionalization of ASD Variants of PTEN in C. Elegans

Background: This study is part of a multi-model platform to functionalize Autism Spectrum Disorder (ASD) gene variants. A primary challenge in studying genes associated with ASD is the lack of an in vivo system in which to rapidly and cost-effectively functionally validate and characterize the large number of candidate risk genes. The sheer number of mutations associated with ASD and the time and money constraints associated with modeling ASD in mammals necessitates an alternative approach.

Objectives: Use the high throughput capacity of Caenorhabditis elegans as an in vivo platform to functionally validate and characterize ASD-associated genes and their variants.
Methods: We have identified a list of high confidence ASD-associated gene variants by combining evidence from >20 exome and whole genome sequence reports. Here, we use our machine vision system, the Multi-Worm Tracker, to characterize morphology, locomotion, and habituation phenotypes of 99 strains of C. elegans covering 87 ASD-associated gene orthologs. In parallel, we have created transgenic C. elegans each expressing a different ASD-associated de novo missense mutation in PTEN in order to validate and assess the functional affects of these putatively pathogenic amino acid substitutions in vivo.

Results: This research has generated a large number of novel genotype to phenotype relationships that range from severe developmental delays and uncoordinated movement to subtle deficits in sensory and learning behaviours, as well as detailed structure-function information indicating which ASD-associated PTEN variants are strong function altering mutations.

Conclusions: This data will be a powerful in vivo tool to identify missense mutations in ASD-associated genes that impact protein function and induce dysfunction in a well characterized neural system assay. Findings will inform future targeted in vivo studies in higher organisms and holds the potential of identifying novel therapeutic targets for ameliorating the effects of ASD.