What is Genetic Carrier Screening?
Genetic carrier screening- what and why?
Genetic carrier screening is a type of testing that can identify if an individual carries a gene mutation which might in turn cause specific genetic syndromes or rare diseases.
It provides individuals with important information about their own genetic health, and can also help them to understand the genetic health of their future children. Generally it is carried out either before marriage or pregnancy, but can be carried out at any point during an individual’s life. As greater awareness about rare diseases, and their causes, grows, so the demand for carrier screening increases too.
The testing itself is very simple, and involves taking a sample of blood, saliva or tissue from the inside of the cheek. It is considered to be a form of non-invasive testing, and there are no risks involved with the testing.
What are the different types of genetic carrier screening?
Targeted carrier screening: this type of genetic screening looks only for specific gene mutations and rare diseases based on ethnicity or family history. For example, in Jewish individuals, it would look specifically for the HEXA gene on chromosome 15, which is responsible for causing Tay-Sachs. If you have a family history of a specific rare disease, so this specific condition will be screened for. This type of carrier screening is very specific, and generally will have a negative/positive result.
Expanded carrier screening: this type of genetic testing involves screening for hundreds of different disorders from one sample. This testing panel is usually determined by the company or organization offering the testing. Generally the testing will focus on the more commonly inherited syndromes, or those that have the largest impact on an individual’s life due to the severity and complexity of their symptoms.
Who should undergo genetic carrier screening?
- If you have a family history of a rare disease, or someone in the family is a carrier of a specific gene mutation for a rare disease.
- If you belong to an ethnic group that is considered to be at higher risk for developing specific inherited rare diseases.
- Anyone looking to understand more about their own genetic health before starting a family.
Genetic carrier screening & genetic counseling
Genetic counseling is an integral part of genetic carrier screening. No genetic screening should be started before embarking on genetic counseling.
Genetic counseling provides the following for those about to begin carrier screening:
- An understanding of their own family history, and which , if any, specific genes should be tested for. This will help determine if someone should opt for targeted or expanded carrier screening.
- An explanation of each of the different testing options for carrier screening, their methods, and what the test is screening for. They will also explain the accuracy of each test, and how to make sense of its results.
- Once the screening is complete, genetic counseling helps individuals understand their own genetic health, and what it means for their future children, if they are indeed carriers of a specific gene or gene mutation.
- An understanding of how rare syndromes are inherited, including the different modes of inheritance. The main modes include autosomal recessive, autosomal dominant, and X-linked inheritance. This understanding is important for carriers to plan future pregnancies.
- Information about options for future pregnancies, if both parents are carriers of a specific gene mutation. This would place any child at high risk of developing a rare disease, and so possible options might include egg or sperm donation, or adoption.
- Recommendations for testing options for other family members, who may also be carriers, or children who may need to be screened for a rare disease based on their parents carrier testing results.
- Emotional support, helping individuals come to terms with their own genetic health, and the impact it could have on their future children’s health.7
Genetic carrier screening is an important genetic health testing option, for all parents-to-be. However, as with any type of genetic testing, genetic counseling is essential in order for individuals to fully understand what the testing involves, what it means, and the implications of any results from the testing. Genetic counseling is an integral and inseparable part of carrier screening, regardless of which type of screening is done, and regardless of which gene mutation or potential rare disease is identified. It is a stage in the process which can not be missed.
