Structural variants exhibit widespread allelic heterogeneity and shape variation in complex traits

Area of Science:

• Genomics
• Population Genetics
• Evolutionary Biology

Background:

• Complex traits exhibit significant variation.
• Individually rare structural variants (SVs) are hypothesized to contribute to this variation.
• Short-read sequencing may miss many SVs.

Purpose of the Study:

• Identify and characterize euchromatic SVs in Drosophila melanogaster.
• Assess the frequency and impact of SVs on gene content and complex traits.
• Determine the proportion of SVs missed by short-read genotyping.

Main Methods:

• Analysis of 14 Drosophila melanogaster genome assemblies.
• Identification of over 20,000 euchromatic SVs.
• Comparison of SV detection with short-read genotyping methods.
• Assessment of SV frequency in genes and association with quantitative trait loci (QTLs).

Main Results:

• Over 20,000 euchromatic SVs identified, with ~40% missed by short-read approaches.
• 31.5% of individuals have SVs in genes >5kb; 24% have multiple SVs in genes >10kb.
• SVs are rarer than amino acid polymorphisms, suggesting they are more deleterious.
• SVs are enriched in QTL candidate genes and harbor functionally important genes.

Conclusions:

• Structural variants are ubiquitous in Drosophila and frequently hidden.
• SVs act as a source of rare alleles with potentially large effects on complex phenotypes.
• SVs contribute significantly to genetic variation and evolution.