Introduction of Whole Exome Sequencing:
Whole exome sequencing (WES) is utilized when medical and family histories indicate a potential genetic origin for the observed signs and symptoms. It is often performed after previous genetic tests have failed to identify the underlying genetic cause of the patient’s condition.
Genes:
Genes act as chemical directives that dictate the functions of a cell. They resemble recipes for producing specific proteins, which play crucial roles in every cell within the body.
Genes are encoded using a four-chemical system represented by the letters A, T, C, and G. These chemicals form a sequence that provides the instructions for protein synthesis. Typically, individuals possess two copies of most genes, inheriting one copy from each parent.
Parts of a Gene:
Genes consist of two primary components: introns and exons. Exons are the segments of a gene that carry the necessary information for protein synthesis. They are considered the “coding” regions of the gene. In contrast, introns are DNA regions located between exons and do not participate in protein coding.
What is the Difference between Exome and Genome?
DNA serves as a unique blueprint for an individual’s existence. The genome encompasses the entirety of a person’s DNA, encompassing both the introns and exons. On the other hand, the exome solely comprises the exons, which are the specific regions utilized in protein synthesis. The introns and other non-coding DNA sequences are not considered part of the exome.
What is Genetic testing?
Various types of genetic tests exist. Some tests analyze the genetic code of an individual gene to detect any alterations within that specific gene. Other tests are designed to identify the presence of additional or missing sections of DNA. In contrast, whole exome sequencing enables simultaneous reading of the exons in a significant portion of genes.
What is a mutation?
A mutation refers to a modification in the DNA sequence. Such alterations can impair the functionality of proteins or prevent their production altogether. If we envision a gene as a recipe for creating a protein, a mutation can be likened to an error in the recipe that leads to abnormal protein function.
Mutations can manifest as “misspellings,” where an incorrect letter is incorporated into the gene, or as deletions or duplications, involving the presence of extra or missing DNA within a gene. It’s important to note that genetic mutations occur randomly. Individuals have no control over causing or preventing mutations from occurring.
What is the method used to perform the test?
Next-generation sequencing (NGS). This advanced technology actively determines the order of nucleotides in entire genomes or targeted regions of DNA or RNA.
What is Next-generation sequencing (NGS)?
Next-generation sequencing methodology allows for the rapid and relatively inexpensive analysis of large amounts of DNA, up to entire genomes. Exome sequencing utilizes next-generation technology to analyze all protein-coding sequences in the human genome.
What is the objective of performing whole exome sequencing?
The primary aim of whole exome sequencing is to identify a genetic explanation for the observed signs and symptoms in an individual or their child. In many cases, individuals who undergo whole exome sequencing have already undergone certain genetic tests. WES is considered one of the most comprehensive genetic tests currently available. By examining a larger number of genes compared to most other genetic tests, WES has the potential to uncover a genetic cause for the signs and symptoms, even if previous genetic testing failed to do so.
What is the procedure for conducting whole exome sequencing?
To perform whole exome sequencing, approximately 3 mLs of blood is collected from the individual undergoing the test. In some cases, blood samples from parents or other family members may also be obtained for comparative analysis. Subsequently, the laboratory will extract DNA from the blood samples. The exons, which are the coding regions, of a majority of genes will be scrutinized. This process encompasses both the person undergoing exome sequencing and any family members who provide DNA samples for comparison purposes.
What is the process of interpreting whole exome sequencing results?
During the interpretation of whole exome sequencing results, your or your child’s DNA will be compared to a standard “reference” DNA sequence, and when applicable, to the DNA of family members. The analysis will identify DNA alterations that deviate from the normal sequence. The laboratory, in collaboration with your doctor or genetic counselor, will utilize various scientific tools and clinical information to determine which genetic changes are potentially responsible for the observed signs and symptoms. The identified genetic changes, which are likely to contribute to the symptoms, will be reported to your doctor for further evaluation and discussion.
How Whole Exome Sequencing is helpful?
Whole exome sequencing (WES) has the potential to uncover the genetic basis for the signs and symptoms experienced by you or your child, which can significantly impact medical care decisions. By obtaining a genetic diagnosis, your family gains valuable information about the likelihood of having other children affected by the same condition. Additionally, this knowledge can be beneficial for other family members, aiding in their understanding and management of potential genetic risks.
What types of results can be anticipated from whole exome sequencing (WES)?
Positive Results:
Whole exome sequencing (WES) can potentially identify a genetic cause for your or your child’s condition. The identification of the genetic basis of the symptoms has the potential to inform adjustments in medical treatment, although it may not definitively predict the outcome of the condition.
Negative Results:
Whole exome sequencing may not uncover a genetic cause for your or your child’s condition. However, a negative result does not necessarily imply that the condition is non-genetic. Various factors, such as the condition lacking a genetic basis, WES’s inability to detect the specific type of genetic change responsible for the symptoms, or the limitations in our current understanding of the exome, can contribute to the absence of findings and affect our ability to interpret the test results.
Uncertain Results:
The test may detect a DNA alteration called a variant of uncertain significance (VUS), which signifies a change in the DNA that may or may not be linked to a disease. Your doctor will guide you on the need for additional testing to obtain a better understanding of these results.
What information does the report generated from the Whole Exome Sequencing test typically include?
Main results:
The report will provide a detailed discussion of genetic changes identified in genes that are likely associated with your or your child’s condition. Additionally, genetic changes detected in family members and relevant to the primary result will be included in the patient’s report.
Secondary Findings:
The patient’s report will also encompass genetic changes in genes that are unrelated to the current disease affecting you or your child. However, these changes may have a significant impact on health. Unless otherwise specified by you, this information will be included in the patient’s report. Further details regarding secondary findings can be found below.
Raw data:
Raw data is available free of charge for download (FASTQ, BAM, VCF files), along with filtered and annotated variant tables (XLS file), providing a wealth of information for further research. Moreover, researchers and scientists can access this data to delve deeper into genetic variations and explore potential associations with various conditions.
What is the difference between Whole Exome Sequencing and Clinical Exome Sequencing?
By focusing on sequencing the exome, Whole Exome Sequencing (WES) allows for the analysis of a significant portion of the genes responsible for protein synthesis. Exons, which represent the protein-coding regions of genes, comprise only a small fraction (about 1-2%) of the entire genome.
On the other hand, Clinical Exome Sequencing takes a narrower approach by targeting specific genes known or suspected to be associated with particular medical conditions or diseases. This focused approach enables a more efficient and targeted analysis of specific genes of interest, based on the patient’s clinical presentation, symptoms, and suspected diagnosis.
While WES comprehensively assesses a broad range of genes, Clinical Exome Sequencing is tailored to the specific clinical context of the patient. Its objective is to identify genetic variants within the selected genes that may explain or contribute to the patient’s presenting symptoms or condition.
In how many days the test reports will come?
You can expect the delivery of your results in 3 to 4 weeks, providing you with valuable insights into your genetic profile. Furthermore, we will include the raw data alongside the results, enabling you to actively explore and analyze the information.
How to Get an Appointment?
To schedule an appointment,
Reach out to our clinic through phone, email, or online contact form. Our friendly staff will assist you in setting up an appointment.
During the consultation, you will have the opportunity to discuss your specific needs, ask questions, and gather information about whole exome sequencing. Our team will guide you through the process, explain the benefits, and address any concerns you may have.
