Whole-exome sequencing (WES) is helping physicians diagnose a genetic condition that has defied diagnosis by traditional means. The implication here is that exons in the nuclear genome are sequenced in the hopes that, by comparison with the genomes of nonaffected individuals, a diagnosis might be revealed.

If you were ordering WES for a patient, would you also include an analysis of the patient's mitochondrial genome?

Key Concepts

Whole-Exome Sequencing (WES)

Whole-exome sequencing (WES) is a genomic technique that focuses on sequencing all the protein-coding regions, or exons, of the genome. These exons represent about 1-2% of the entire genome but contain the majority of known disease-related variants. WES is particularly useful for diagnosing genetic disorders that are difficult to identify through traditional methods, as it allows for a comprehensive analysis of the coding regions.

Mitochondrial Genome

The mitochondrial genome is the genetic material found in mitochondria, the energy-producing organelles in cells. Unlike nuclear DNA, which is inherited from both parents, mitochondrial DNA is maternally inherited and is crucial for cellular energy metabolism. Analyzing the mitochondrial genome can be important in diagnosing certain genetic conditions, especially those related to energy production and mitochondrial dysfunction.

Comparative Genomics

Comparative genomics involves comparing the genomic features of different organisms to understand the function and evolution of genes. In the context of WES, this approach allows clinicians to compare the patient's exonic sequences with those of nonaffected individuals to identify potential pathogenic variants. This comparison is essential for making accurate diagnoses and understanding the genetic basis of diseases.