Gene expression variation across genetically identical individuals predicts reproductive traits

Area of Science:

• Genetics
• Developmental Biology
• Molecular Biology

Background:

• Genome-wide association studies (GWAS) explain limited individual differences in complex traits.
• Environmental factors significantly contribute to trait etiology, causing variation even in genetically identical individuals.
• Distinguishing genetic from environmental causation is challenging.

Purpose of the Study:

• Investigate the basis of individual differences in gene expression in the absence of genetic variation.
• Identify genes and mechanisms driving non-genetic contributions to trait variation.
• Assess the predictive and causal roles of gene expression in trait determination.

Main Methods:

• Measured reproductive traits in 180 genetically identical *Caenorhabditis elegans*.
• Performed single-individual transcriptomics on each worm.
• Manipulated mRNA levels of predictive genes and analyzed chromatin environment.

Main Results:

• Identified hundreds of genes with expression variation associated with reproductive traits.
• Small gene sets accurately predicted over half and a quarter of variation in two traits.
• Demonstrated causal roles for specific genes and linked expression variation to chromatin structure (H3K27 trimethylation).

Conclusions:

• Individual, non-genetic differences in gene expression are highly predictive of traits.
• Gene expression variation is causal in shaping reproductive traits.
• Chromatin structure may contribute to non-genetic gene expression variation.