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Exome Sequencing for Clinical Diagnosis

Exome sequencing is a key tool for clinical diagnosis, as it allows us to identify genetic variations which are capable of causing many types of inherited diseases.

The exome is the part of the genome which if formed by exons. These are fractions of DNA which are in charge of coding for proteins that make up an organism. Studying the exome is therefore one of the most thorough and complex ways of analysing a person’s DNA, as there are many genetic diseases or pathologies which are associated directly to mutations in the exome DNA.

What does Exome Sequencing Consist of?


Exome sequencing is a Next Generation Sequencing (NGS) method which is widely used for DNA analysis of the protein coding regions of the genome.

We must bear in mind that even though the human exome represents under 2% of the entire genome, it contains around 85% of the known variants related to pathologies.

Therefore, exome sequencing has become one of the most promising methods for clinical diagnosis, without needing to sequence the subject’s entire genome.

 

Advantages of Exome Sequencing


Exome sequencing has various advantages in the realm of clinical amplification.

Its profitability stands out in the cases where whole-genome sequencing is not necessary. Being able to exclusively analyse the coding regions allows investigators to focus their efforts on inspecting the genes with a much greater probability of being the cause of the disease. This therefore optimizes the cost-effectiveness of the whole process.

Another advantage we can consider is how concise the information is when obtained, meaning that the amount of data collected is smaller and more manageable. This shortens the time required for analysis compared to sequencing an entire genome.

In scientific investigation, exome sequencing also has multiple applications for detecting and analysing the genetic variants which lead to human diseases, such as those related to cancer, mendelian disorders, and others with more complex inheritance patterns.

Bioarray works with the Illumina NovaSeq platform for Exome Sequencing, using the Agilent SureSelect Human All Exon V6 capture kit. These systems allow for a greater enrichment efficiency, as they achieve 90% uniformity in coverage and over 90% nucleotides at 20X sequencing depth.

Nevertheless, we must understand the importance of showing the results in full detail. For this reason, Bioarray offers a complete bioinformatic analysis of the Exome Sequencing results.

 

 

New tools in Exome Sequencing


 

Human Phenotype Ontology (HPO)


There are thousands of hereditary diseases in human beings, each of which has its own specific combination of phenotypical characteristics.

For this reason, investigators and professionals have searched for tools to analyse the correlations between phenotypes and genetic mutations to discover the biological functions of certain genes.

Thanks to bioinformatics and new tools for computer analyses, platforms such as Human Phenotype Ontology (HPO)https://hpo.jax.org/app/ have been developed in order to cover all phenotypical anomalies.

 

Exome Sequencing for CNV detection


The development of new databases and technological advances have allowed bioinformatics to use data from Exome Sequencing to find Copy Number Variants (CNVs) : deletions or duplications which can be picked up with Exome sequencing and later verified with MLPA or microarrays.

Exome sequencing has become one of the most adequate tools for the analysis of CNVs, as we can obtain excellent coverage of the regions to be analysed for a more economic price than by other methods.

This way, Exome Sequencing has opened a new era in which genetics and bioinformatics become the key tools for diagnosis of clinical pathologies and improve the scientific investigation of these topics, helping with new discoveries.