Exoomsequencing

Exoomsequencing, commonly written as exome sequencing, is a genomic technique for sequencing all protein-coding regions of the genome. By capturing exons with probes and sequencing them with high-throughput next-generation sequencing, researchers and clinicians can identify genetic variants that cause disease. The exome comprises about 1–2% of the genome but contains the majority of known disease-caising variants.

The standard workflow involves DNA extraction, library preparation, and targeted capture of exons using hybridization-based probes (in-solution or array-based) or amplification-based methods. The captured material is sequenced on platforms such as Illumina, producing reads that are aligned to a reference genome, followed by variant calling, annotation, and interpretation. Coverage depth and uniformity are important considerations, influencing the sensitivity for detecting variants.

Applications include diagnosing suspected Mendelian disorders, guiding rare disease gene discovery, and analyzing cancer genomes for somatic mutations and potential therapeutic targets. Exome sequencing is often preferred over whole-genome sequencing when a coding-region etiology is likely and when cost, data interpretation, or turnaround time are limiting factors. It is also used in population genetics studies and pharmacogenomics.

Limitations include incomplete or uneven coverage of some exons, particularly in GC-rich or poorly represented regions, and the inability to reliably detect non-coding variants, regulatory elements, or certain structural variants and copy number changes. Some exons may be missed entirely, and results may require confirmatory testing. Ethical, regulatory, and clinical considerations apply in diagnostic use, including informed consent and appropriate result disclosure.