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Frequently Asked Questions about Genetic Testing

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What is genetic testing?
Genetic testing is a method for diagnosing inherited disorders What is an inherited disorder?

Inherited disorders are caused primarily by changes in a gene sequence rather than by environmental influences. Since genes are passed on within families, an inherited disorder is also passed on within families.
. Genetic tests detect genetic variations (also called mutations) in a gene sequence. Since inherited disorders are associated with certain genetic variations, finding such disease-causing variations in an individual’s genes can allow diagnosis of the disorder.

The vast majority of inherited disorders can be caused by any one of many different genetic variations within one specific gene or within any one of several specific genes. Therefore, genetic testing involves screening all those regions of a gene (or of several genes) where genetic variation most often leads to disease. This type of genetic testing is also known as full-gene sequencing. Even full-gene sequencing, however, cannot guarantee detection of all disease-causing genetic variation. Therefore, genetic testing can only confirm, but not exclude presence of disease or high risk of disease.

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What is genetic family testing?
Genetic family testing can both confirm and exclude presence of disease or high risk of disease in members of an affected family, by detecting presence or absence of the familial mutation. The familial mutation is the specific genetic variation that causes all cases of an inherited disease within one extended family. Why are related patients likely to harbor the same disease-causing genetic variation, given that two unrelated patients typically harbor two completely different genetic variations? If a parent harbors the disease-associated genetic variation, his or her children each have a 1 in 2 chance of inheriting the parental mutation. In contrast, the general risk of harboring a disease-associated genetic variation is much lower (<1:100 for most inherited disorders). It is therefore much more likely that members of a family affected with an inherited disorder inherit the familial mutation than that they harbor a different disease-associated genetic variation. Importantly, once a familial mutation is known, this knowledge stays within the family forever and can facilitate diagnosis of the disease through many generations.

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What are the benefits of genetic testing?
In many cases, genetic testing is only one of several tools for diagnosing a specific inherited disease. However, genetic testing offers many important benefits over other diagnostic tests. It can:

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Can patients directly order genetic testing?
For most conditions, genetic testing can only be ordered through a physician, to guarantee that this diagnostic tool is used only when appropriate and that its results are considered in the context of all other medical information for a patient.

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Is genetic testing covered by insurance?
Insurance coverage varies with the insurance provider.

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Can genetic testing lead to discrimination by an employer?
On May 21, 2008, a bill prohibiting discrimination by employers based on personal genetic information (known as GINA - the Genetic Information Nondiscrimination Act) was signed into law. GINA prohibits employers from denying employment based on personal genetic information and from collecting personal genetic information about their employees without their explicit consent. In addition to GINA, many states have passed their own legislation to prevent discrimination based on genetic information.

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Can genetic testing lead to discrimination by health-insurance providers?
On May 21, 2008, a bill prohibiting discrimination by health insurers based on personal genetic information (known as GINA - the Genetic Information Nondiscrimination Act) was signed into law. GINA prohibits health-insurance providers of group or individual health care plans from denying coverage or adjusting premiums based on an individual’s personal genetic information.

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Can genetic testing lead to discrimination by life-insurance providers?
Unfortunately, this is often the case. Parents may choose to enroll their children in a life insurance plan before obtaining genetic testing for them.

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Does every genetic variation found in a disease-associated gene cause disease?
No. While some genetic variations are known, believed, or suspected to cause disease, others constitute normal variation seen throughout the general population.

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What are variants of unknown significance and possible disease variants?
A genetic variation (or variant) of unknown significance may or may not be associated with disease. A possible disease variant is suspected to be associated with disease, but this association remains quite uncertain. More information is needed to clarify the significance of such genetic variations. Over time, this information may become available in the literature. Genetic testing of affected individuals within the patient’s extended family (known as concordance testing) may also yield this information. If all affected family members harbor the genetic variation in question, it is likely to be associated with the familial disease. If some affected family members do not harbor the genetic variation in question, it is less likely to be associated with the familial disease. Clarifying the significance of a genetic variation through concordance testing not only benefits this particular family, but also other families who harbor the same genetic variation.

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Can genetic testing predict severity of disease?
Genetic testing can usually not predict severity of disease, although exceptions do exist. Typically, the results of genetic testing only indicate the probability of disease or risk of disease. In other words, a genetic variation definitively known to be associated with disease may cause a milder than usual form of the disease, while a genetic variation only suspected to be associated with disease may, in fact, cause a particularly severe form of the disease.

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More Information

For more information on individual state laws against genetic discrimination, please visit the website of the National Conference of State Legislatures at http://www.ncsl.org/research/health/genetics-overview.aspx

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