June, 2020
Director of Deep-Sequencing Lab: PHD. Rosenbluh Chaggai, |
[email protected] Director of Bioinformatic Analysis: PHD. Mor Shaked Hagar|
[email protected]The Hadassah Deep-Sequencing Laboratory is part of the Genetics Dept. and is located on the 5th floor of the Ein Kerem Campus.
Administrative staff:
Mrs. Bruria Dadon, 02-6776931, ext. 5 |
[email protected] Ms. Shiraz Tashra, 02-6779307 |
[email protected]
What is exome sequencing?
In whole exome sequencing analysis we read the genetic sequence in search of genetic variants that may be disease-causing.
The human DNA consists of segments called genes, separated by regulatory regions. The genes themselves are made up of exons that are the code for synthesizing proteins in the human body, and of introns that are additional internal regulatory sequences. While exons make up only about 1% of the entire human genome, it is generally accepted that changes in them are responsible for approximately 80% of all human genetic diseases. Thus, by sequencing only the exon sequences, we are able to detect a large fraction of these genetic diseases at a very reasonable cost. This assay is called Whole Exome Sequencing, and it is performed on a Deep Sequencer.
Here at Hadassah we offer both the 'wet-lab' sequencing service, complemented by our expert team of bioinformatic analysts. We are proud to use the most advanced sequencing platform available today – the Illumina NovaSeq6000. Our in-house team of bioinformaticians was the first in Israel, and one of the first in the world, to apply WES analysis in a clinical setting. Since starting in 2011, we have gained extensive expertise in the clinical analysis of exome sequencing results.
When should you consider exome sequencing?
Exome sequencing is only performed following a referral by a doctor or genetic counselor.
Typically, exome sequencing is offered to patients whom we suspect are suffering from a genetic disease.
Exome sequencing may also be performed during pregnancy; in this case we sequence DNA extracted from fetal sample obtained by chorionic villi sampling or an amniocentesis.
How long will it take to get results?
Exome sequencing results are typically available within 10-days. In urgent, high-priority cases, we try to provide results within as little as 4 days.
What is the chance that exome sequencing will lead to a diagnosis?
We will be able to offer a conclusive diagnosis to approximately 60% of our patients. This depends on the disease from which the patient suffers, the family background, and many other variables.
During exome sequencing, we discover many variants, most of which are frequent in the population, while others are rare. We compare the patient's variant list to a healthy control and try to isolate the disease-causing variant using multiple bioinformatic tools. These tools allow us not only to identify single nucleotide variants, but also more complex disease causing changes, including, among others, deletions, duplications, and uniparental disomies.
Even if we are unable at the time of testing to reach a conclusive prognosis, the genetic information stays in our database and is re-evaluated periodically, allowing us on occasion to solve cases that were initially unresolved. The raw sequencing data is also available to the patient and can be transferred upon request.
What is the cost?
At present (2020) Whole Exome Sequencing costs about 2,200NIS per test, including analysis and interpretation. In addition to this, we have recently added mitochondrial DNA sequencing to the suite of services we offer, and this is now included in all our exome sequencing analyses, free of charge.
Can we request a second re-evaluation of data generated in another facility?
Yes. If a patient has sequenced their exome elsewhere and wishes to have our team of experts look over the data and re-analyze it, we are happy to do so. In this case we will need the patient to transfer the raw sequencing data to us, and we will re-evaluate it over the course of a few days. It is important to remember that methods in exome sequencing and analysis vary between institutions, and for that reason it is possible that re-analyzing the data may lead to a diagnosis that differs from the original.
Second-opinion re-evaluation costs approximately 1000NIS.