What is genetic testing?
Genetic testing is a tool used to determine if a person is a carrier of a specific altered gene that causes a particular medical condition.
What are the different types of genetic testing?
The different types of genetic tests and their purpose are:
- Diagnostic genetic testing: to diagnose a person with a genetic condition. Cystic fibrosis or Huntington’s disease may be determined.
- Predictive genetic testing: to determine the likelihood that a person will develop a genetic disease before they have symptoms. This usually occurs when the medical condition is inherited. This can be useful in determining the risk of certain types of colorectal cancer.
- Preimplantation testing: used when trying to conceive a child through in vitro fertilization, as embryos are screened for genetic abnormalities. Embryos without abnormalities are implanted in the uterus.
- Prenatal testing: to find a genetic disease in the genes of an unborn baby. Down syndrome and trisomy 18 syndrome are two disorders that are tested for during prenatal genetic testing. This is done by looking at markers in the blood. Newer tests, called cell-free DNA testing, can sample the baby’s DNA using a blood test from the mother.
- Newborn screening: offered to babies in their first six to eight weeks. For babies with health problems, the benefits are enormous, as newborns are screened for certain genetic and metabolic abnormalities that can cause certain conditions.
- Carrier testing: Patients are advised to have this test before having children if they have a family history of a genetic disorder, such as sickle cell disease or cystic fibrosis. Some ethnic groups are at increased risk for some genetic disorders.
- Pharmacogenetics: this can help determine what medication and dosage would be most effective if someone has a health condition or disease.
Genetic testing is a tool used to determine whether a person is a carrier of an altered gene.
How is genetic testing performed?
There are different ways to perform the test, which collects samples that will be sent to a laboratory for analysis. These include:
- Blood sample
- Cheek swab
- Amniocentesis: used for prenatal genetic testing, a thin needle is inserted through the abdominal wall into the uterus to take a sample of the amniotic fluid.
- Chorionic villus sampling: also used for prenatal testing, the physician takes a sample from the placenta.
What is genetic counseling?
Genetic counseling provides support, information and advice to those who have been referred to a genetic counselor by the physician. A health care professional will assess the underlying condition in the family and how it may be affecting the patient and family. The counselor will consider the risk of a couple passing on an inherited condition to their child and offer support if the patient wishes to have another child. The counselor may also discuss the different types of genetic testing, including the risks and benefits of each.