Ch. 18 - Genomics, Bioinformatics, and Proteomics

Klug - Essentials of Genetics 10th Edition

Klug10th EditionEssentials of GeneticsISBN: 9780135588789Not the one you use?Change textbook

Klug 10th Edition

Ch. 18 - Genomics, Bioinformatics, and Proteomics

Problem 22b

Chapter 18, Problem 22b

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?

Verified step by step guidance

Understand that Whole-exome sequencing (WES) targets the exons of nuclear DNA, which are the protein-coding regions of the nuclear genome.

Recognize that the mitochondrial genome is separate from the nuclear genome and consists of a small circular DNA molecule found in mitochondria, which is not covered by standard WES.

Consider that many genetic conditions can be caused by mutations in mitochondrial DNA, which would not be detected by WES alone.

Therefore, if a mitochondrial disorder is suspected or if the clinical presentation suggests mitochondrial involvement, it is important to order a separate analysis specifically targeting the mitochondrial genome.

In summary, WES does not include mitochondrial DNA analysis, so to comprehensively evaluate genetic causes, especially those related to mitochondria, a dedicated mitochondrial genome analysis should be included.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.

Video duration:

39s

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Whole-Exome Sequencing (WES)

WES is a genomic technique that sequences all the protein-coding regions (exons) of nuclear DNA. Since exons represent about 1-2% of the genome but harbor most known disease-causing mutations, WES is efficient for identifying genetic variants linked to disorders. It focuses on nuclear DNA and typically excludes non-coding regions and mitochondrial DNA.

Mitochondrial Genome and Its Role in Disease

The mitochondrial genome is a small, circular DNA molecule found in mitochondria, inherited maternally and separate from nuclear DNA. Mutations in mitochondrial DNA can cause distinct genetic disorders, often affecting energy metabolism. Because WES targets nuclear exons, mitochondrial DNA is usually not analyzed unless specifically requested.

Diagnostic Strategy for Genetic Disorders

Choosing which genomic regions to analyze depends on the suspected disease and inheritance pattern. For unexplained conditions, including mitochondrial genome analysis alongside WES can be crucial if mitochondrial disease is suspected. Comprehensive diagnosis may require combining nuclear and mitochondrial DNA sequencing to capture all possible genetic causes.

Recommended video:

Guided course

03:45

Descriptive Genetics

Related Practice

Textbook Question

An interactive Web site for the Human Proteome Map (HPM) is available at http://www.humanproteomemap.org. Visit this site, and then answer the question.

Use the 'Query' tab and select the 'Gene family' dropdown menu to do a search on the distribution of proteins encoded by a pathway of interest to you. Search in fetal tissues, adult tissues, or both.

536

views

Textbook Question

Researchers have compared candidate loci in humans and rats in search of loci in the human genome that are likely to contribute to the constellation of factors leading to hypertension [Stoll, M., et al. (2000). Genome Res. 10:473–482]. Through this research, they identified 26 chromosomal regions that they consider likely to contain hypertension genes. How can comparative genomics aid in the identification of genes responsible for such a complex human disease? The researchers state that comparisons of rat and human candidate loci to those in the mouse may help validate their studies. Why might this be so?

601

views

Textbook Question

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.

What are the strengths and weaknesses of this approach?

519

views