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Information About Genetic Testing

Genetic testing involves looking at a person’s DNA to find changes that may have been passed down from a parent, or acquired during a person’s lifetime. These changes could be linked to inherited diseases or conditions like cancer. Testing can focus on specific genes, which are sections of DNA containing instructions for making proteins, or on chromosomes, which are bundles of DNA found in cells. DNA is made up of adenines (A), thymines (T), guanosines (G), and cytosines (C) (refer to Figure 1). These appear in a very specific order in a gene and gene tests search for changes in this order. These changes could affect how a gene works, potentially leading to it not working at all or functioning incorrectly.

Figure 1. DNA Sequence
Image Courtesy of NHGRI
Figure 1. DNA Sequence

There are many different types of genetic testing, including:

Diagnostic testing

Helps make or rule out a specific diagnosis in a person with symptoms of a genetic condition

Predictive or pre-symptomatic testing

Predicts disease in a person without signs of the disorder in question

Susceptibility testing

Determines whether a healthy individual is more likely to develop a specific disease

Carrier testing

Identifies individuals who may be at risk to have a child with a recessive disorder

Prenatal diagnosis

Performed during pregnancy on the baby's DNA.

Pharmacogenetic testing

Determines how a person will respond to a specific medication

Genetic testing is different from other medical tests in several important ways. First, it can give insights into potential future diseases for someone who is currently healthy. These diseases include Alzheimer’s, cancer and others. Second, the results of genetic tests can impact decisions about having children, planning a family, and other important life choices. Moreover, these results can shed light on the health status of other family members and reveal unexpected discoveries, like non-paternity.

Genetic Counseling

Due to the complexities of genetic testing and its potential impact on individuals and their families, it is generally recommended that anyone thinking about genetic testing seek genetic counseling. Genetic counseling helps individuals and families to understand complex medical information and inheritance patterns. Additionally, it plays a crucial role in assessing the risks, benefits, and limitations of the genetic test(s) being considered. Ultimately, genetic counseling empowers individuals to make decisions in line with their beliefs and values and helps them adapt to the information they receive.

Genetic counseling services are provided by specially trained healthcare providers who have significant experience with genetics and the unique nature of genetic testing. Genetic counselors are healthcare providers with graduate degrees from programs accredited by the American Board of Genetic Counselors (ABGC). Their training includes both medical genetics and psychology. A local, board-certified genetic counselor may be found through the National Society of Genetic Counselors.

Genetic Testing for Alzheimer’s Disease

In 2011, the American College of Medical Genetics (ACMG) and the National Society of Genetic Counselors (NSGC) published guidelines regarding genetic testing for Alzheimer’s disease (AD). These guidelines state that APP, PSEN1, or PSEN2 gene testing may be considered in individuals with a personal and family history consistent with early-onset AD inherited in a dominant manner. However, they emphasize the importance of genetic counseling and informed consent before such testing. For individuals with a personal or family history consistent with late-onset AD, APOE gene testing is possible but not currently recommended. In addition, genetic testing for AD (APP, PSEN1, PSEN2, or APOE) should not be done for any individual under the age of 18.

Clinical genetic testing for AD must be ordered by a physician. However, currently, most major insurers consider this testing experimental or investigational. Therefore, APP, PSEN1, PSEN2, and APOE gene tests may not be covered by many insurance plans.

Genetic Discrimination

Thanks to the rapid progress in medical genetics, we have a better understanding of how changes in our DNA can affect our health and predisposition to various diseases. These genetic changes can influence the likelihood of genetic syndromes, cancer, and common adult-onset conditions like diabetes, heart disease, and Alzheimer’s disease. They can also indicate how a person might respond to specific treatments or medications. Overall, genetic testing has become an essential tool in diagnosing genetic disorders, predicting future diseases, and managing individuals affected by or at risk of conditions with a genetic basis. However, many individuals are concerned about the potential misuse of their genetic information. Due to these concerns and past instances of genetic discrimination, a law addressing this issue was passed in 2008.

The Genetic Information Nondiscrimination Act (GINA), which took effect in 2009, protects individuals from genetic discrimination. This law defines genetic information as both the results of genetic testing and family medical history, such as a relative with a known genetic condition or carrying a disease-related gene change. Title I of GINA applies to healthcare coverage and prevents insurers from using genetic information to determine eligibility, coverage, or premiums. It prohibits insurers from treating family medical history or genetic test results as pre-existing conditions. It also says that insurers cannot require a plan member to get genetic testing. Title II of GINA addresses employment-related discrimination by prohibiting employers with 15 or more employees from using genetic information in decisions concerning hiring, promotion, or termination. In addition, employers cannot request genetic testing or genetic information from their employees.

GINA does not cover genetic conditions that have already been diagnosed based on their symptoms. In addition, GINA does not cover other types of insurance, such as life insurance, disability insurance, or long-term care insurance.

Additional Information

For more information about genetic testing and genetic counseling:

For more information about genetic testing for AD (including the guidelines discussed above):

For more information regarding genetic discrimination: