Genetic testing can help doctors look for changes in genes that can cause diseases or disorders. As doctors learn more about the genetic causes of and genetic influences on disease, genetic testing can provide important clues about the origin of disease or symptoms.
Genetic testing can also provide families with more information about long-term needs, health care needs, and future family planning. Genetic testing has both risks and benefits, and it is important to talk with your health care provider or a genetic counselor about the pros and cons of testing.
Working with a licensed genetic counselor (LGC) will help ensure that you understand the benefits and limitations of the test, the cost of testing, possible results, the implications of those results, the results of the tests and have the information needed to make informed decisions about the results.
When Is Genetic Testing Appropriate for My Child?
Your doctor might recommend genetic testing if you have a family history of a genetic disease or if your child has symptoms of a condition that has been associated with a genetic disorder.
Some conditions or symptoms that may be linked to a genetic disorder include:
Developmental delays in motor, speech or cognitive function
Anatomical birth defects in two or more organs
Hearing or vision impairment
Cancer (usually before the age of 50)
Heart rhythm problems
What Types of Genetic Testing Are Performed?
Genetic testing is performed on a small sample of blood, tissue or saliva. Some genetic tests look for specific variations or analyze certain genes. These tests, called gene panels, are used when the physician ordering the test has a good idea about what genes could be linked to the symptoms or conditions.
Other genetic tests look to analyze the whole genome (all the genetic code found in a person’s DNA) or whole exome (all the genetic material that codes for proteins produced in the body). These tests (whole exome and whole genome sequencing) are most often used when doctors can’t find a reason for a person’s symptoms after a gene panel or if the symptoms are very broad and do not point to a specific condition. Many rare diseases have been discovered through whole genome or exome sequencing.
What Does It Mean for the Rest of the Family If a Genetic Variant Is Found?
Sometimes, genetic variants that cause disorders are inherited from biological parents. Every person has two copies of every gene. One copy is inherited from each parent. If the gene is associated with an “autosomal recessive” condition, a person must have causative variants in both of the gene copies in order to have the disorder. If the gene is associated with an “autosomal dominant” condition, only one copy having a causative variant is needed for the person to be affected. If the genetic disorder is caused by a gene located the X-chromosome (girls have two copies of the X chromosome, while boys have one), it is called an “X-linked” disorder. X-linked disorders, such as hemophilia, are seen more often in boys than girls.
Genetic conditions can also result from a spontaneous or de novo – not inherited – mutation in a gene. Or from mutations in mitochondrial DNA found in the mother’s egg.
Depending on the type of mutations found by genetic testing, families might choose to work with a doctor and genetic counselor to decide if additional family members need to get tested.
Abbie Roth, MWC, is a passionate communicator of science. As the managing editor for science communication at Nationwide Children’s Hospital, she shares stories about innovative research and discovery with audiences ranging from parents to preeminent researchers and leaders.
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