What are the Most Common Genetic Tests?
Carrier screening
Genetic carrier screening is one of the most common genetic tests. It is often recommended to couples who are thinking about starting a family, and in some countries it is often a part of standard preconception testing and preparation.
The aim of carrier screening is to identify genetic changes in an individual, or pair of individuals, that might affect the health of their future children. Carrier screening, combined with genetic counseling, can also inform parents-to-be about inheritance patterns, and if their combined genetic health may lead to a rare disease in their children.
Carrier screening is only relevant to genetic mutations and rare diseases that can be inherited, and not those cases where they occur randomly or as the result of a new mutation.
Prenatal genetic tests
Prenatal genetic tests have developed into perhaps the most common of all genetic tests. This is in large part due to an increased awareness about their existence and their ability to identify rare diseases before an infant is born.
Some prenatal genetic tests are able to diagnose a rare disease. These diagnostic tests include amniocentesis and chorionic villus sampling. Other forms of prenatal genetic screening options can only identify increased risk, or not, for specific rare diseases in infants.
Prenatal genetic screening is now commonly a part of standard prenatal care, in the developed world.
Recently the development of cell-free DNA testing, and non-invasive prenatal testing have increased the availability of genetic testing to parents-to-be where the health of their unborn child is concerned. They have also helped increase awareness around the causes of rare disease.
Newborn screening
Genetic screening for a newborn is a common form of genetic testing. In the US it is performed on newborns as a part of their standard post birth care. It can diagnose specific genetic syndromes, many of which can have a significant impact on the health and life of an infant in the first few months of their life.
Generally parents will only receive a result from newborn screening if it identifies potential higher risk for a specific condition.
Diagnostic testing
Diagnostic testing is a common type of genetic test used to screen for specific rare syndromes, if a doctor or genetic counselor suspects an individual may be at risk for one.
An individual may be deemed as needing diagnostic genetic testing for the following reasons:
-A parent or sibling was diagnosed with a rare disease
-Their parents are carriers of a gene mutation that can be inherited, dependent on its inheritance pattern. Rare diseases inherited in a recessive pattern, require that both parents be carriers of the gene mutation for their child to potentially be affected. Rare diseases inherited in a dominant pattern, mean only one parent may pass down the gene mutation for a child to be affected by the consequent genetic syndrome.
-They show symptoms that suggest a rare disease or syndrome
-Genetic screening, either before or after birth suggested higher risk for a rare disease
Types of diagnostic genetic testing include karyotype and chromosomal microarray, depending on the rare disease being tested for.
For genetic testing to be accurate and return a diagnosis that is correct, it is important that as much information as possible is known about the family medical history of the individual, as well as their own medical conditions and symptoms. Genetic testing is not able to test for every known gene mutation and syndrome, it is targeted and requires some idea of what to test.
In order to improve the accuracy of even the most common genetic tests, genetic counseling should be a critical part of the process. Genetic counseling and the services it provides ensure that genetic testing is more precise for the individual or family concerned.
