Exome (eg, unexplained constitutional or heritable disorder or syndrome); sequence analysis
CPT4 code
Name of the Procedure:
Exome Sequencing (also known as Whole Exome Sequencing or WES)
Summary
Exome sequencing is a genetic test that analyzes the exons, or protein-coding regions, of an individual's DNA. This test can identify genetic variants that may be responsible for unexplained medical conditions or inherited disorders.
Purpose
This procedure aims to diagnose genetic conditions by identifying mutations in the exome. It is particularly useful for:
- Individuals with unexplained medical symptoms.
- Patients with suspected genetic disorders.
- Families with a known hereditary condition seeking more information.
The goal is to provide a precise diagnosis, leading to targeted treatments and better management of the condition.
Indications
- Unexplained developmental delays or intellectual disabilities.
- Uncommon or atypical symptoms not easily diagnosed through standard tests.
- A family history of a genetic disorder.
- Support for personalized treatment plans based on genetic information.
Preparation
- No specific preparation is generally needed.
- Pre-test genetic counseling is often recommended to discuss potential outcomes and implications.
- A blood sample or saliva sample is typically required.
Procedure Description
- A blood or saliva sample is collected from the patient.
- The DNA is extracted from the sample.
- The exome is sequenced using high-throughput sequencing technologies.
- Bioinformatics analysis is performed to identify genetic variants.
- Genetic counseling is provided to discuss the results.
Tools and Equipment:
- High-throughput sequencers.
- Bioinformatics software for data analysis.
Duration
The entire process, from sample collection to results, can take several weeks to a few months.
Setting
The procedure is performed in a laboratory setting. Sample collection can occur in various locations such as hospitals, outpatient clinics, or through at-home kits.
Personnel
- Geneticist or genetic counselor.
- Laboratory technicians.
- Medical geneticists or genetic specialists.
Risks and Complications
- Psychological impact due to unexpected or distressing results.
- Incidental findings unrelated to the primary reason for testing.
- Risk of misinterpretation without adequate genetic counseling.
Benefits
- Precise diagnosis of genetic disorders.
- Informed decision-making for treatment and management.
- Potential to uncover new information about rare genetic conditions.
Recovery
- No physical recovery is needed; it's a non-invasive test.
- Post-test genetic counseling is crucial to discuss results and plan next steps.
Alternatives
- Targeted gene panels focusing on specific suspected genes.
- Chromosomal microarray analysis for copy number variations.
- Whole-genome sequencing for a more comprehensive analysis.
Pros and Cons of Alternatives:
- Targeted gene panels are faster and less expensive but less comprehensive.
- Chromosomal microarray might miss single-gene mutations detected by exome sequencing.
- Whole-genome sequencing is more comprehensive but more costly and data-intensive.
Patient Experience
- Sample collection is quick and straightforward, with minimal discomfort.
- The waiting period for results can be anxiety-inducing.
- Genetic counseling ensures understanding and support throughout the process.