Whole Exome Sequencing (WES) Test

Many diseases have a genetic basis, with the primary cause being the mutation of a specific gene. Therefore, genetic diagnosis is the medical tool used to understand the genetic causes behind the development of a disease.

In this case, whole exome sequencing helps detect the gene and mutations that cause the disease. This test involves determining the 4-letter code (A, T, C, and G) that makes up all the exons of a specific patient.

If the genetic information is altered (mutation), it means that the proteins being synthesized cannot perform their function correctly, leading to the onset of diseases.

Once the exome sequencing is completed, it is compared with another sequence where there are no alterations, in order to identify the mutation that caused the genetic disease, providing a precise and rapid diagnosis.

Throughout this text, you will find all the information about sequencing: from what an exome is to the methodology and advantages of this genetic test.

The human genome (the set of DNA molecules) is made up of over 20,000 genes, which contain all the information needed to synthesize all the proteins in our body.

Genetic information is not continuous; it is interspersed between exons (coding regions) and introns (non-coding regions). Exons provide the information for protein synthesis, while introns are interspersed within the gene and serve other functions.

In other words, the human genome is made up of portions called exons, separated by spacer regions known as introns.

The set of exons in our genome is what we refer to as the exome. Therefore, the human exome consists of 180,000 exons, which make up 1% of the total genome, or about 30 megabases of DNA.

In some cases, the combination of symptoms presented by certain patients makes it difficult to establish a clear diagnosis. This leads to a long journey of medical consultations for the patient until a diagnosis is finally found.

When this happens, it is advisable to perform a genetic test to identify the cause of the disease.

A delayed diagnosis can have a significant impact on the patient’s quality of life.

Whole exome sequencing is a genetic test that represents a comprehensive and step-by-step strategy. The techniques used to sequence the exome allow for a precise and rapid diagnosis. Additionally, based on the results, informed decisions can be made regarding treatment and medical care. But why turn to whole exome sequencing?

A large portion of diseases caused by mutations that have been identified so far have been located in the exons. Some genetic tests focus on a single gene or a set of predetermined genes, whereas the whole exome sequencing test examines thousands of genes simultaneously.

The reasons for opting for this genetic test are as follows:

• When it is difficult to establish a diagnosis.
• When a broader genetic study is needed.

Possible results of Whole Exome Sequencing

Once the whole exome study is completed, four possible outcomes may arise:

1. A genetic alteration or alterations are detected that have caused the disease being studied in your case.
   
   
2. Similarly, one or more alterations are identified in the genes, but the significance is uncertain or unclear. In such cases, it will be necessary to study the exome of other family members to determine whether the alteration is key to explaining the disease.
   
   
3. No alteration is found that explains the disease. If this happens, the study may continue when sufficient literature becomes available regarding the genes to be studied.

When analyzing the whole exome sequencing, there is a possibility that alterations unrelated to the disease being studied may be detected.

The whole exome sequencing test is recommended for all patients with an unclear clinical diagnosis. This genetic medical test helps identify many diseases with a genetic basis.

Having an early genetic diagnosis that confirms the clinical diagnosis allows for addressing the disease with all the necessary information to anticipate clinical stages and provide appropriate follow-up according to the type of disease.

Therefore, whole exome sequencing is indicated for people with:

• Intellectual disability / developmental delay
• Cardiomyopathies
• Epilepsy
• Muscular dystrophy
• Ataxia Neuropathy
• Deafness
• Retinitis Pigmentosa
• Bone and connective tissue disorders
• Undiagnosed metabolic disorder
• Short stature
• Complex dysmorphic disorder
• Immunodeficiency

On the other hand, it is important to note that whole exome sequencing is not a test that should be performed as a first option. When there is suspicion of a genetic disease, it is appropriate to conduct a full study.

A medical prescription is required to perform the whole exome sequencing test.

However, if you have one of these conditions or if your symptoms are somewhat confusing and you have the necessary medical prescription, you can purchase this test and undergo whole exome sequencing by clicking on the following image:

Do you need to perform a Whole Exome Sequencing test?

Purchase your medical voucher, select your nearest Megalab laboratory and identify the genetic causes behind the development of a disease.

Purchase Test

Whole exome sequencing is performed using a sample of blood, a small amount of saliva, or cheek cells to obtain your DNA. The technology used to sequence the entire exome represents an advance in genetic diagnosis.

The methodology for conducting whole exome sequencing is as follows:

1. Sample Collection: a sample is taken and the relevant bibliographic data is prepared to optimize the workflow and reduce response times.
   
   
2. Alignment and Sequencing: the resulting sequence is aligned with the genome to identify genetic variants.
   
   
3. Analysis of Variants: the variants are analyzed and potentially pathogenic diseases are identified.
   
   
4. Interpretation of Results: finally, the clinical geneticists at Megalab interpret the results and prepare a report.

Once the sample is collected, the Megalab genetics team will explain how to access your results:

• You will be provided with an access code to enter your private area.
• From there, you can check the status of the results report.
• If the results are not available, the status will show as "pending".
• Additionally, you will receive the contact number for the laboratory where you underwent the test, should you have any questions while waiting for the results.

After Megalab sends the results, you will be able to schedule a consultation with a genetic counselor over the phone to discuss the implications of the results.

In addition to the blood sample and its analysis, the phone consultation with the genetic counselor is included in the cost of the test. During the consultation, the geneticist will explain the interpretation of the results.

The goal of whole exome sequencing is to obtain the maximum genetic information from the patient, searching for genetic variants across the more than 20,000 genes that make up the exome, thus determining the appropriate course of action.

Whole exome sequencing allows for a detailed study of the coding sequences, that is, the genetic regions that contain information.

This genetic test enables the transcription of DNA, in addition to offering several advantages, such as:

• Currently, it is the genetic test with the highest diagnostic performance.
• As you know, this test studies a variety of genes, so it is likely that new genes with clinical significance will be identified. This helps expand the clinical phenotype, that is, the expression of the genotype (genetic information) based on the environment to which it is exposed.
• It is also capable of detecting new variants or genes associated with the studied pathology that have not yet been described.
• It allows for the resolution of complex diagnostic cases.

The whole exome sequencing test can be performed at any Megalab center you choose, without the need to book an appointment in advance.

Through our website, you can purchase the whole exome sequencing test. Shortly afterward, you will receive an email with the voucher for this medical test.

Whole Exome Sequencing at Megalab Centers

Megalab is one of the largest laboratories in Spain, with over 25 years of experience and a well-established track record. It operates in 54 private hospitals across Spain, serving more than 4,500 hospital beds.

In addition, it has a network of over 60 laboratories throughout the country and provides services to all medical societies, healthcare centers, and hospital management companies.

More than 500 centers send samples to Megalab’s headquarters in Madrid, where around 10,000 analyses are performed daily, including whole exome sequencing.

If you have a valid medical prescription or a personal or family history that warrants the test, you can purchase the Whole Exome Sequencing test by clicking on the image below.

If you have any questions, Operarme’s Patient Service Department will be happy to assist you immediately at +34 91 141 33 56, or you can fill out the contact form, and we will call you.

Do you need to perform a Whole Exome Sequencing test?

Purchase your medical voucher, select your nearest Megalab laboratory and identify the genetic causes behind the development of a disease.

Purchase Test