Genetic Testing Company | The DNA Diagnostic Experts | GeneDx


Frequently Asked Questions








Specimen Requirements

Q: Do you prefer a blood specimen over the buccal brush specimen? Is there any difference?
A: The accuracy and turnaround time of the testing is the same between a blood specimen and a buccal brush specimen. We prefer blood specimens for all our tests. Please check test information sheets to see tests for which buccal brushes can be used.

Q: Can I use a buccal (cheek) brush kit that isn’t a GeneDx kit?
A: We strongly encourage you to use a GeneDx kit to collect a cheek brush sample. We have optimized our procedures in the laboratory for use with our kits. The worst case scenario is that we cannot complete the test and must request a second specimen. If we receive a kit that is not ours or if a specimen appears to be suboptimal, we generally perform a quick test to determine if the DNA is of a high enough quality to run the test that was ordered. If the DNA is not adequate, we will contact the person who sent the specimen to request another one. This is usually accomplished within the first week of receiving a specimen. Unanticipated problems can arise with any specimen, however, and with each case we make every effort to reduce the time between when we receive a specimen and when we ask for a second one.

Q: Why can’t I use a cheek brush kit for certain tests?
A: For some tests, the quality of DNA required to complete the testing in a timely manner cannot be obtained from a buccal sample. Such tests include: quantitative PCR (CopyDx), MLPA, microarray (GenomeDx, prenatal array analysis, ExonArrayDx), whole exome sequencing (XomeDx), and all Next-Generation sequencing tests. Please see test-specific requirements on test information sheet or our website for acceptable specimens.

Q: I am drawing a specimen from an infant. What is the minimum amount of blood required?
A: We would like at least 1-2 cc of whole blood in EDTA (purple top tube) to perform any test.

Q: Can buccal brush specimens be collected on infants?
A: We have had less success in obtaining adequate DNA from buccal brush specimens on infants under the age of 6 months. Therefore, we request blood specimens (1-2 cc of whole blood in EDTA) on small babies.

Q: If more than one test is being ordered on the same patient, is it better to provide a tube of blood for each test?
A: No. GeneDx obtains enough DNA from one specimen to complete a number of tests. We generally discard all but 5 milliliters of whole blood on a patient, because more than that is unnecessary and we have limited space in which to store specimens. Pediatric patients usually don’t require more than 2 milliliters. 

Q: What are the specimen requirements for prenatal testing?
A: The following specimens are necessary for completion of a prenatal test:

  • Maternal blood (1-4 ml in a purple-top EDTA tube) is required for maternal cell contamination (MCC) studies. The maternal sample should accompany the prenatal specimen or be shipped to arrive prior to or concurrently with the prenatal sample.
  • *Maternal and Paternal blood is required for prenatal array testing.
  • If more than one prenatal test is being ordered on a specimen, one of the following is required: 30 ml of Amniotic fluid, 30 mg of Chorionic villi, 3 T25 flasks of cultured amniocytes or cultured chorionic villi.
  • In multiple pregnancies, a separate requisition form is required for each fetus.

Please click here for printable instructions for collecting a prenatal sample.

Q: Can I order more shipping kits?
A: Yes, you can order shipping kits easily through our website under Shipping Supplies or by sending an email to

Q: Can I send DNA?
A: Yes. Please send a minimum volume of 20 ul and minimum concentration of 50 ng/ul (50 ug/ml). For testing on a single exon, we require 1-2 ug of DNA. If we are testing 2-10 exons, we require 5-10 ug and for tests with more than 10 exons, we need 20 ug. For specific DNA requirements please click here.

Q: If a patient has had a bone marrow transplant, what types of specimens can I send for testing?
A: Skin punch and tissue biopsies are acceptable after a bone marrow transplant. Blood, saliva, buccal and oral rinse kits are NOT acceptable after a bone marrow transplant. 

Q: If a patient has had blood transfusion, is there a waiting time before I can send a sample for genetic testing?
A: The only tests that require a waiting period after blood transfusion are mitochondrial genome tests that are measuring a level of heteroplasmy in the blood. For the following tests, we recommend waiting 3-4 weeks after a blood transfusion before drawing a blood sample for DNA testing:

            615: Combined Mito Genome Plus Mito Nuclear Gene Panel

            554: Full sequence analysis and deletion testing of the mitochondrial genome

            704: 58 mtDNA point mutations plus large deletions panel

            444: Deletion/duplication analysis of the mito genome

            453: Testing of One of the Three mtDNA mutation(s) with heteroplasmy

            690: XomeDxPlus

            9017: Testing for one mtDNA mutation without heteroplasmy

For all other tests, no waiting period is required before submitting a blood sample for testing. 

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Q: Where do I send a specimen?
A: Attn: Accessions
GeneDx, Inc.
207 Perry Parkway
Gaithersburg, MD 20877


Q: How do I send a specimen?
A: A specimen should be packed in materials that prevent its container from being damaged during shipment. Unlabeled specimen tubes should be labeled with patient name and date of birth. Specimen tubes will be rejected by GeneDx. Cheek brush specimens can be sent through the regular postal mail using the envelope addressed to GeneDx that is included with the kit. Blood, prenatal and other specimens should be shipped to us using an overnight delivery service. Minimally, the specimen should be shipped to us with a completed sample submission (requisition) form and payment options form. For more information visit our Specimen Requirements page.

Q: Can I ship specimens by regular postal mail?
A: Cheek brush samples or DNA may be shipped by regular mail. All other types of samples should be sent by overnight or second-day delivery for receipt Monday through Saturday. If a sample is collected on a Friday evening or over a weekend then it should be kept in the refrigerator and shipped on the next business day for overnight delivery. Keeping the specimen refrigerated over the weekend will not compromise the quality of the specimen.

Q: Does GeneDx pay for shipping?
A: No, the cost of shipping is the responsibility of the sender. GeneDx provides shipping kits with prepaid FedEx labels for US customers only. To order a kit visit Supply Ordering.


Required Paperwork

Q: What paperwork do I need to include?
A: Minimally, you will need to complete the Requisition Form and the Payment Options Form and include these with the specimen. Specimens without proper ordering or payment information will be held until the appropriate information is provided to us.


Q: Is the consent document required?
A:You are not required to send GeneDx a completed consent document according to the federal regulations governing clinical laboratories. However, for your convenience, we do provide consent forms for each test we offer. It is important to know that your state government may require documentation of the informed consent process (for a listing, see: In addition, although GeneDx does not require the consent form to accompany the sample, we recognize that the informed consent process is an important component to any genetic testing protocol and encourage practitioners to obtain informed consent from patients being tested.



Q: Does GeneDx accept insurance?
A: Yes, visit our Billing Page for more information on insurance and payment options.

Q: Does GeneDx accept my state’s Medicaid?
A: GeneDx is a registered provider with several Medicaid plans. Although we are a registered provider with these plans, prior authorization is required for Medicaid samples and must be obtained by the ordering physicians office. In an instance where we receive a Medicaid sample without a prior authorization, the test will go on hold and not proceed in the lab. In most cases, Medicaid will not cover genetic testing for these conditions, as Medicaid coverage varies by state. For more information, please call  us at 301-519-2100.

Q: Can I set up an institutional billing account?
A: There is generally no need to set up an account with us if you are shipping specimens from a hospital laboratory or physician’s office. Simply provide the contact information (name, phone and fax numbers, and address) to which we can mail an invoice and CPT codes for the services rendered.


Results and Analysis

Q: Why are the results of testing sent directly to the referring physician rather than the patient or parent of a patient?
A: Genetic testing is usually performed as a tool to help the physician make a diagnosis or to help a physician manage a patient’s health care. Because the results of genetic testing may lead to additional testing, it is best for the physician to receive the results so that an appropriate plan for the care of the patient can be determined. In addition, the results of genetic testing can be complicated and difficult to understand. In most cases it is best to report the results to a healthcare professional who has both a relationship with and the time to explain such results to the patient or patient’s parents.


Q: Is my test finished yet?
A: Our goal is to provide you with an accurate result in a reasonable time period. The time it takes to complete a test varies depending on a number of factors such as the size of the gene, the complexity of the interpretation, the occasional need to redesign primers or confirm an abnormal result.  The information page for each condition indicates an estimated turn around time for completion of the test. These estimates are based on the average amount of time it has taken us to complete the test in the past. As soon as a test is completed the results are sent to the referring physician or ordering facility. Positive test results and tests performed on prenatal specimens are also called if a physician’s phone number is provided to us.

Q: The test result has been lost or was never received, can you resend it?
A: GeneDx can provide you with a duplicate copy of the test result if you are the ordering physician or are from the ordering facility. We cannot send results to the patient or other physicians involved in the care of the patient without a signed release from the patient authorizing us to do so. When calling for a report, please let us know the first and last name of the patient and when the specimen was sent.

Q: I received an invoice, but not the result.
A: Billing occurs separately from the laboratory analysis and bills are sent out shortly after the specimen is received at GeneDx. We understand that many lab policies require the results before a payment is made. Second notices are faxed out 60 days after the report is issued.

Q: Can a test be expedited?
A: All prenatal specimens are expedited. If there are other medical indications for expediting a test, please let us know and we will do our best to get a result out as quickly as possible. The most common indications for expediting a test in the lab are a scheduled or necessary procedure (e.g. surgery, bone marrow transplant) and testing on a pregnancy or family member of a pregnant woman.


Adding on Tests

Q: I would like to order another test on a patient who was tested previously. Do I need to submit another specimen?
A: No. Generally, GeneDx obtains enough DNA from one specimen to allow completion of a number of tests. A second specimen is not necessary.


Q: What is the procedure for adding on further testing to a sample already at GeneDx?
A: An additional test can be added on to a sample already at GeneDx by submitting a written request or required paperwork (Add-on form) for the new test to be performed. This request can be faxed or emailed to GeneDx at 301-519-2892 or


Contact Information

Q: Can I speak to the person in charge of ordering supplies and marketing at GeneDx?
A: The easiest way to reach us at GeneDx is by email. Please send your question to and it will be delivered to the appropriate person.

Certifications and important numbers

Q: What is your CLIA identification number?
A: Our CLIA identification number is 21D0969951.


Q: What is GeneDx’s tax ID number?

Q: Are you CAP certified?
A: Yes.

Q: Are your tests FDA-approved?
A: No. Our tests are developed and validated in-house and the FDA has determined that such clearance or approval is not necessary.

Q: Do you have a New York state license?
A: Yes. Please see our New York Test List.

Q: Does GeneDx comply with the EU Safe Harbor Framework?
A: The company complies with the U.S.-EU Safe Harbor Framework as set forth by the U.S. Department of Commerce regarding the collection, use, and retention of personal information from European Union member countries. The company has certified that it adheres to the Safe Harbor Privacy Principles of notice, choice, onward transfer, security, data integrity, access, and enforcement. To learn more about the Safe Harbor program, and to view the company’s certification, please visit


Downloadable Forms

Q: How can I open the downloadable forms from your site?
A: To view documents in PDF format, you need to install Adobe Acrobat Reader, a free application distributed by Adobe Systems. All test requisition forms are available here.

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