*Please note: The information provided below is in reference to our "known familial mutation testing" only and does not apply to all tests we offer.*

Familial Known Mutation Testing

What is Familial Testing? What Can the Test Tell Me? Benefits of Testing Limitations of Testing Costs Turn-Around-Time for Results What is Familial Testing?                   If previous genetic testing has identified a mutation(s) known to cause disease (called pathogenic) in your family, then you or your family members can also undergo testing specifically for that mutation(s). Testing will allow you to determine if you have also inherited the mutation(s) and are at risk to develop the disease in your family. This test is called a familial known mutation test and differs from the original test performed. This test looks only for the specific mutation(s) identified in your family. For autosomal dominant, mitochondrial, and X-linked conditions, the test looks for one mutation, where as for autosomal recessive conditions two mutations are tested. Mutations "hold true" in a family. This means that within a family, anyone who has the disease will usually have the same mutation(s) as his/her relative. It is extremely uncommon to find two individuals in a family with the same disease caused by different mutations. If the significance of the mutation found in your family is unknown (the result stated as inconclusive on the report) then please contact the lab and speak to a genetic counselor before pursuing familial known mutation testing. What Can the Test Tell Me? Testing for a familial mutation(s) will tell you whether or not you inherited the disease present in your family. If the result of the test is negative, then you do not have the mutation and are now at the same risk as the general population to develop the disease. If the result is positive, it means you were found to have the mutation. For instance, a person found to have a mutation causing an autosomal dominant disease like Li Fraumeni Syndrome in his/her family, he/she is now at increased risk to develop the disease and has a 50% (or 1 in 2) chance to pass this same mutation onto his/her children. In recessive conditions like cystic fibrosis and some forms of hearing loss, a person found to have one mutation is considered a carrier for that condition. Carriers are not at risk to develop the disease. If a person is found to have two mutations, then he/she has the disease. A positive result does not always mean that an individual will develop the disease. The severity of some diseases is affected by other factors, such as diet or other environmental exposures. To understand the meaning of a positive test result, please contact the lab and speak with a genetic counselor. Benefits of Testing: For autosomal dominant conditions like Marfan syndrome, identification of a mutation confirms the diagnosis. Testing the parents of an individual with an autosomal dominant condition will allow you to also determine if the mutation was inherited or sporadic (a new occurrence in the patient). Testing the patient's mother for X-linked and mitochondrial mutations can provide similar information. This information is important in order to provide accurate recurrence risks for future pregnancies. In a disease with reduced penetrance like hypertrophic cardiomyopathy (HCM), if an individual has no signs and symptoms of the disease and is found to have the mutation, then he/she remains at increased risk to develop the disease and cardiac surveillance is recommended but they may also never develop HCM. In autosomal recessive conditions like cystic fibrosis, known mutation testing of an affected child's parents can confirm that each parent is a carrier for the disease and allow for accurate risk assessment for future pregnancies of this couple. Testing of the parents in autosomal recessive conditions also allows one to determine if a single mutation was inherited from each parent, if both mutations were inherited from a single parent, or if either of the mutations were new occurrences in the child, which would change the recurrence risks provided to the parents. Confirming that each parent carries a single mutation also helps to confirm a diagnosis in some children. Help ease uncertainty and anxiety about one's genetic status Can eliminate the need for unnecessary follow up and reduce medical costs (if negative) May allow for earlier detection and prevention (if positive) Guide physicians in patient management based on the severity of the mutation found (if positive) Make more informed family planning decisions Limitations of Testing: Potential negative emotional impact Feeling guilty about not having the mutation ("survivor guilt") or having passed it on Anxiety about what the future holds (if positive) Insurance Discrimination Please refer to the Genetic Discrimination section under the Resources page of our website for more information. Costs: Testing for one mutation: $250 Testing for two mutations: $300 Turn-Around-Time for Results: 2 weeks from the time we receive the sample. Sample Requirements: Sample can be blood or saliva. Please refer to the Ordering Page of our website for more information on how to send a sample. Download a pdf version of this document Return To The Table Of Contents If you have any questions, please call the Laboratory for Molecular Medicine at 617-768-8500 or email us at LMM@partners.org