Page Contents:

• How does testing typically work?

• Saliva Samples

• Buccal Samples

• Blood Samples

• Spinal Fluid

• Somatic Cells

Depending on the type of genetic testing being performed, individuals may need to provide specific sample types in order to get accurate results from the laboratory. Genetic testing facilitated by Clover Genetics can almost always be performed using a provided saliva swab to collect your sample. However, in some instances, blood or other samples may need collected to perform the correct analysis based on each person’s testing recommendations.

If you decide to pursue genetic testing through Clover Genetics, our team will assist you through a very simple process.

The General Process:

1. Schedule an appointment with Clover Genetics

   • Use a “Referral Form” from your physician to expedite testing

     • NOTE: If you do not have a physician who can sign off on your testing, we can facilitate physician review for a small fee

   • If you have health insurance, provide the information so that it can be used for genetic testing if possible.

     • NOTE: we do not accept insurance for our genetic counseling services, but the genetic testing may be covered by your insurance and may be used at the laboratory for the testing portion of the bill

2. Discuss your options for genetic testing during your appointment

3. Receive a sample kit in the mail

   • For those submitting self-administered samples, you can collect your sample at home!

   • Read the instructions on the kit thoroughly and ensure that you strictly follow them when collecting your sample

     • Saliva and buccal samples are the only options we offer for self-administered sample collection; blood samples can be collected at home by a mobile phlebotomist (see “Blood Samples”).

4. Return the kit to the lab via mailing the package with pre-paid postage

5. Schedule a follow-up appointment with your genetic counselor to review your results

   • We will notify you of the anticipated date of when we should have your test results so that we can schedule a follow-up appointment to discuss your results as soon as they’re received

   • During this appointment, based on your results, we will discuss any risks for your parents, siblings, and children and discuss options for additional care or testing

   • We will provide you with resources and personalized support!

Saliva Sample

Saliva is a viscous watery fluid secreted in the mouth by the salivary glands primarily as the first step in digesting food. Saliva samples are a non-invasive method of collecting DNA.1

• How is it generally performed?

• First, the patient must read all instructions on the kit before collecting a sample. After waiting approximately 30 minutes without eating, drinking, smoking, or chewing gum, the patient allows some saliva to collect in their mouth, then spits it into a sterile plastic tube. 5

• Examples of different tests saliva samples can be used for:

• Single-gene testing: Cystic Fibrosis

• Multiple-gene testing: Spinal Muscular Atrophy

• Gene-panel testing: carrier screenings, cancer risk panels

• Whole Exome Sequencing

• Whole Genome Sequencing

Buccal Sample

Buccal testing is the painless removal of some epithelial cells from the inside of the cheek. It can often be done by the patient themselves with a buccal swab kit. 

• What types of testing can be completed?

• Example 1: Sex chromatin test (for sex determination)(7).

• Example 2: SNP (single nucleotide polymorphism) multiplex analysis, such as with prelingual deafness screens (GJB2 variant)(8).

• How is it generally performed?

  • The patient may not eat, drink, chew gum, or smoke for at least 30 minutes prior to sample collection. A sterile swab is rubbed against the inside cheek (without touching the teeth) to collect a sample. The swab is inserted into the collection tube, and the tube must be shaken to mix the sample (9).

• What conditions CANNOT be identified through these samples?

  • Buccal swabs are not recommended for patients with allogenic bone marrow or stem cell transplants due to the high presence of donor DNA (10).

Blood Sample

Blood is the fluid that transports oxygen and nutrients to cells and carries away waste products and metabolites. Blood tests are one of the most common forms of both general medical and genetic testing (11). Blood is collected from veins in a procedure known as venipuncture.

• What types of testing can be completed?

• Example 1: Non-Invasive Prenatal Screening (NIPS) can be performed on pregnant people as part of a prenatal genetic screen because fetal chromosomes are present in maternal serum. This allows for doctors to examine the fetal DNA without collecting cells from the fetus itself (11).

  • NOTE: It is important to keep in mind that this is a screening, NOT a test. That means that it is looking for possibly concerning genetic changes in the fetal DNA within the maternal blood. Any positive results must be followed-up on with direct testing (not screening) of the fetal DNA via either amniocentesis, products of conception, or waiting and testing the newborn.

• Example 2: Non-genetic blood tests such as complete blood cell (CBC) counts and tumor marker tests can be performed to identify and diagnose certain cancers, particularly leukemias and other blood cancers (12).

• How is it generally performed?

• A lab professional specifically trained for drawing blood, or phlebotomist, ties a rubber band around the arm and inserts a sterile needle into a vein in the patient’s arm to collect a sample (13).

• Mobile Phlebotomy: in-home blood draws may be offered for specific locations. The provider will request a test, and the testing company will reach out and schedule a time with the patient. Results are sent to the provider.  

• What conditions CANNOT be identified through these samples?

• While blood tests are close to 100% accuracy for identifying chromosomal aneuploidies, like Down Syndrome, Trisomy 13, and Trisomy 18 (33). However, prenatal blood tests have low accuracy in testing for smaller chromosomal rearrangements or deletions, particularly for conditions like Prader-Willi or DiGeorge syndrome, where prenatal blood tests can be false in up to 90% of cases (15).

Spinal Fluid

Cerebrospinal fluid (CSF) is a clear liquid that surrounds the brain and spinal cord. Its purpose is to cushion the brain and spinal cord to protect it from injury (19).

• What types of testing can be completed?

• Example 1: CSF testing can investigate DNA changes in cancer cells within the brain through analyzing cell-free DNA (cfDNA) from circulating tumors:

  • Tumor cfDNA is enriched with CSF compared to blood, especially for those with tumors in the central nervous system, such as the brain or spinal cord, also called CNS-limited neoplasia(20).

• Example 2: CSF testing can sometimes differentiate between disorders causing rapid progressive dementia:

  • Creutzfeldt-Jakob Disease (CJD): degenerative brain disease that affects muscle coordination and memory

• Example 3: CSF testing is differential in those with undiagnosed degenerative brain disorders (21):

  • Gerstmann-Straussler-Scheinker disease (GSS): degenerative brain disease caused by misfolded proteins or prions. CSF testing can assist in analysis of certain protein markers.

• How is it generally performed? A healthcare professional obtains CSF through a lumbar puncture, sometimes called a spinal tap, where the needle is inserted between the third and fourth lumbar vertebrae of the spine (22). This procedure has to be done in a hospital.

• What conditions CANNOT be identified through these samples? Data from the analyzed markers alone are not specifically linked to any diagnosis. They only indicate the presence of axonal injury and point to neurological disorders that may indicate such a process, like Multiple Sclerosis, inflammatory demyelinating diseases, and others (23).

Somatic Cells

Somatic cells refer to all cells in the human body other than sperm and egg cells. Somatic cells contain two sets of chromosomes (28). Unlike germline testing, which searches for inherited genetic conditions, somatic testing looks for acquired mutations in a confined set of cells, like those of a tumor (29).

• What types of testing can be completed?

• Example 1: Cancerous tissue is analyzed by identifying spontaneous mutations in an isolated sample (29). Genomic information obtained from somatic testing can also be used to identify prognosis and suitable treatments, such as targeted drugs (30).

• Example 2: Facioscapulohumeral Muscular Dystrophy (FSHD) utilizes muscle biopsies to test for a missing section of DNA in chromosome 4. It may also be performed on blood cells (31).

• How is it generally performed? A piece of tissue or tumor is collected through biopsy or surgery under a medical setting. The cells from that tissue are then processed and the DNA is analyzed (29).

• What conditions CANNOT be identified through these samples? Detection of certain variants known to be associated with hereditary cancer syndromes is limited- additional testing with saliva or blood is typically required to confirm these syndromes. Large deletions and duplications in particular may not be picked up by paired germline-somatic testing (31).

Citations:

1. Bellagambi, F. G., et al. (2020, March). Saliva Sampling: Methods and devices. An overview. TrAC Trends in Analytical Chemistry 124. https://doi.org/10.1016/j.trac.2019.115781 

2. N.A. (n.d.). “What are the different types of genetic tests?” Medline Plus. https://medlineplus.gov/genetics/understanding/testing/types/ 

3. N.A. (n.d.). “Whole Exome Sequencing” Yale Medicine. https://www.yalemedicine.org/conditions/exome-sequencing 

4. Brown, T. A. (2002). “Understanding a Genome Sequence” Genomes, 2nd Edition. Oxford Press. https://www.ncbi.nlm.nih.gov/books/NBK21136/

5. N.A. (n.d.). “Saliva Testing.” ZRT Labs. https://www.zrtlab.com/sample-types/saliva/ 

6. Uribe-Alvarez, C., et al. (2021, May 5). Low saliva pH can yield false positive results in simple RT-LAMP-based SARS-CoV-2 diagnostic tests. PLoS ONE 16(5): e0250202 https://doi.org/10.1371/journal.pone.0250202 

7. Chernecky, C.C. and Berger, B. J. (2013). Barr body analysis buccal smear for staining sex chromatin mass-diagnostic. Laboratory Tests and Diagnostic Procedures, 6th Edition. St. Louis, MO: Elsevier Saunders, pp 186-187. ISBN: 9781455706945. https://evolve.elsevier.com/cs/product/9781455706945?role=student

8. Babovic-Vuksanovic, D., et al. (1999, June 4). Guidelines for buccal smear collection in breast-fed infants. Am J Med Genet 84(4): 357-360. https://onlinelibrary.wiley.com/doi/10.1002/(SICI)1096-8628(19990604)84:4%3C357::AID-AJMG9%3E3.0.CO;2-4 

9. McMichael, G. L., et al. (2009, Dec). DNA from Buccal Swabs Suitable for High-Throughput SNP Multiplex Analysis. J Biomol Tech 20(5): 232-235. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2777348/ 

10. Gaur, R., et al. (2021, May). Buccal swabs as non-invasive specimens for detection of severe acute respiratory syndrome coronavirus-2. J Int Med Res 49(5): 03000605211016996. https://journals.sagepub.com/doi/10.1177/03000605211016996 

11. N.A. (2020, December). “Prenatal Genetic Screening Tests.” The American College of Obstetricians and Gynecologists. https://www.acog.org/womens-health/faqs/prenatal-genetic-screening-tests.

12. N.A. (n.d.). “How is Cancer Diagnosed?” Stanford Medicine. https://stanfordhealthcare.org/medical-conditions/cancer/cancer/cancer-diagnosis.html 

13. N.A. (n.d.). “Blood Test.” Johns Hopkins Medicine. https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/blood-test 

14. Liu, M. C. (2021, April 27). Transforming the landscape of early cancer detection using blood tests—Commentary on current methodologies and future prospects. Br J Cancer 124(9): 1475-1477.  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8076196/ 

15. Kliff, S. and Bhatia, A. (2022, January 1). “When They Warn of Rare Disorders, These Genetic Tests Are Usually Wrong.” The New York Times. https://www.nytimes.com/2022/01/01/upshot/pregnancy-birth-genetic-testing.html.

16. Antonella, G., et al. (2015, October 1). Conservative and timely treatment in retained products of conception: a case report of placenta accreta retention. Int J Clin Exp Pathol 8(10): 13625-13629. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4680531/ 

17. Dahdouh, E. M. And Kutteh, W. H. (2021, March 22). Genetic testing of products of conception in recurrent pregnancy loss evaluation. Reproductive Biomedicine Online 43(1): 120-126. https://doi.org/10.1016/j.rbmo.2021.03.015 

18. N.A. (n.d.). “Cytogenetics Products of Conception (POC) Chromosome Analysis.” Labcorp. https://womenshealth.labcorp.com/tests/180/cytogenetics-products-of-conception-poc-chromosome-analysis 

19. N.A. (n.d.). “Cerebrospinal Fluid (CSF) Leak” Johns Hopkins Medicine. https://www.hopkinsmedicine.org/health/conditions-and-diseases/cerebrospinal-fluid-csf-leak 

20. McEwen, A. E., et al. (2020, February 18). Beyond the Blood: CSF-Derived cfDNA for Diagnosis and Characterization of CNS Tumors. Front Cell Dev Biol 8: 45. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7039816/ 

21. Ladogana, A., et al. (2009, May 15). Cerebrospinal fluid biomarkers in human genetic transmissible spongiform encephalopathies. J Neurol 256(10): 1620-1628. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3085782/ 

22. N.A. (2023, April 29). “CSF analysis.” Icahn School of Medicine at Mount Sinai. https://www.mountsinai.org/health-library/tests/csf-analysis 

23. Deisenhammer, F., et al. (2019, April 12). The Cerebrospinal Fluid in Multiple Sclerosis. Front Immunol 10: 726. https://www.frontiersin.org/articles/10.3389/fimmu.2019.00726/full 

24. Fitzsimmons, E. D., and Bajaj, T. (2023, July 17). Embryology, Amniotic Fluid. Treasure Island, FL: StatPearls Publishing.  https://www.ncbi.nlm.nih.gov/books/NBK541089/ 

25. N.A. (n.d.). “Amniocentesis (amniotic fluid test).” Medline Plus. https://medlineplus.gov/lab-tests/amniocentesis-amniotic-fluid-test/ 

26. N.A. (n.d.). “Amniocentesis.” Johns Hopkins Medicine. https://www.hopkinsmedicine.org/health/treatment-tests-and-therapies/amniocentesis 

27. N.A. (n.d.). “Chromosome Analysis, Amniotic Fluid.” Mayo Clinic Laboratories. https://genetics.testcatalog.org/show/CHRAF

28. Hurle, B. (2023, August 21). “Somatic Cells.” National Human Genome Research Institute. https://www.genome.gov/genetics-glossary/Somatic-Cells 

29. Norquist, B. (2022, November 30). “Germline vs Somatic Testing; Genomic vs Genetic Testing — What it means and Why it Matters.” Ovarian Cancer Research Alliance. https://ocrahope.org/news/germline-vs-somatic-testing-genomic-vs-genetic-testing/ 

30. Kate Reed, E. (2019, February). Somatic Testing: Implications for Targeted Treatment. Seminars in Oncology Nursing 35(1): 22-33. https://doi.org/10.1016/j.soncn.2018.12.009 

31. N.A. (n.d.). “Diagnosis: Facioscapulohumeral Muscular Dystrophy (FSH, FSHD).” Muscular Dystrophy Association. https://www.mda.org/disease/facioscapulohumeral-muscular-dystrophy/diagnosis#:~:text=Today%2C%20the%20most%20reliable%20way,4q35%20region%20of%20chromosome%204.

32. Quinlan, M. (2008, May). “Amniocentesis: Indications and Risks.” AMA Journal of Ethics. https://journalofethics.ama-assn.org/article/amniocentesis-indications-and-risks/2008-05

33. Zhu H, Jin X, Xu Y, Zhang W, Liu X, Jin J, Qian Y, Dong M. Efficiency of non-invasive prenatal screening in pregnant women at advanced maternal age. BMC Pregnancy Childbirth. 2021 Jan 26;21(1):86. doi: 10.1186/s12884-021-03570-6. PMID: 33499806; PMCID: PMC7836475. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7836475/