Exome Screening completed by Next Generation Sequencing is used to screen individuals and couples for unidentified hereditary diseases or polygenic diseases. Polygenic diseases are those that usually involve two or more genes interacting. Next Generation Sequencing is the new generation of technology that has brought DNA sequencing to an unprecedented speed. In contrast to current sequencing tests that analyze one gene or small groups of related genes at a time, Exome Screening will analyze important regions of tens of thousands of genes at the same time. Fakih IVF Fertility Center is one of the few IVF centers in the Middle East with Next Generation Sequencing technology.
What is Exome Screening?
Exome Screening is a highly complex test, newly developed for the identification of changes in an individual’s DNA that are causative or related to medical concerns. In cases where a disease is believed to be polygenic or unknown, Exome Screening by Next Generation Sequencing is recommended. Polygenic diseases are those that are caused by two or more genes interacting whereas monogenic diseases are caused by a mutation in a single gene. The exome refers to the portion of the human genome that contains sequences of DNA that direct the body to make proteins essential for the body to function properly. These regions of DNA are referred to as exons. It is known that most of the errors that occur in DNA sequences that then lead to genetic disorders are located in the exons. In contrast to current sequencing tests that analyze one gene or small groups of related genes at a time, Exome Screening will analyze the important regions of tens of thousands of genes at the same time. Based on international studies, Exome Screening is expected to provide a diagnosis in up to 50% of the cases for rare and ultra-rare disorders. Once a mutation has been identified through Exome Screening, further steps are followed to confirm the importance of the found mutation before recommending next steps.
Who is a candidate for Exome Screening?
Exome Screening is most often recommended for couples who believe that they are carriers of a genetic disease but the genetic disease has not been previously diagnosed or it is a polygenic disease. Polygenic diseases are those that are caused by two or more genes interacting whereas monogenic diseases are caused by a mutation in a single gene. In some cases, if there is a known case of a family member effected by hereditary disease, the couple may complete Mutation Screening rather than Exome Screening. In general, couples in the following situations are recommended to complete Exome Screening:
- Couples in which either spouse has a family history of hereditary disease and the disease is unknown
- Couples who previously had a genetically abnormal child
- Couples who are close or distant relatives and know of a family history for genetic disease and the disease is unknown
What is Next Generation Sequencing?
Next Generation Sequencing is the new generation of genetics technology that has brought DNA sequencing to an unprecedented speed, enabling impressive scientific achievements. Detecting mutations in monogenic diseases, diseases caused by a mutation in a single gene, is usually easily performed utilizing Mutation Screening by Sanger Sequencing methods. In these cases, accurately identifying responsible mutations can predict disease development with high accuracy. However, such monogenic diseases tend to be fairly rare. Polygenic diseases, diseases that usually involve two or more genes interacting, are more common than their monogenic counterparts. Until recently, genetic testing technology to identify polygenic diseases was not readily available to individuals and couples. The advent of technologies, such as Next Generation Sequencing, in which multiple genes and larger areas of the genes can be tested simultaneously and efficiently, has recently changed the face of genetic testing.
What is the turn-around-time for Exome Screening?
The international turn around time for Exome Screening can vary from 6 months to 1 year. At Fakih IVF Fertility Center, Exome Screening results will be available 8 weeks after completing a consultation with our geneticists and having your blood withdrawn.
If you believe that you are a carrier of a genetic disease or would like to discuss you family history with a genetic counselor, contact the Genetics team at Fakih IVF Fertility Center today by emailing firstname.lastname@example.org