Whole genome sequencing streamlines diagnosis

Answers from the Lab

Expert groups recommend whole genome sequencing for patients with congenital anomalies, developmental delay, or intellectual disability. In this test-specific episode of the "Answers From the Lab" podcast, Nicole Boczek, Ph.D., and Sarah Barnett, M.S., CGC, describe Mayo Clinic laboratories' whole genome sequencing test, which interrogates nearly every base pair of an individual's DNA.

"Genome sequencing can provide a quick diagnosis," Barnett says. "Studies have shown that broad-based genome testing resulted in direct changes to treatment recommendations in about 20% of patients, eliminated the need for additional invasive medical procedures in almost a quarter of patients, and had a clinical impact in more than half of patients."

Other genetic tests — such as exome sequencing and microarray testing — cover fewer variant classes and regions of the genome.

"Whole genome sequencing is advantageous because it can be the most comprehensive and cost-effective genetic testing method for patients who have clinical features that do not neatly fit within one specific disorder, or who have a suspected genetic disorder that may have many underlying genetic causes," Dr. Boczek says.

Listen to learn more about Mayo Clinic Laboratories' new whole genome sequencing test.

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Additional testing

Useful information

Serving as a first-tier test to identify a molecular diagnosis in patients with suspected genetic disorders, which can allow for:

  • Better understanding of the natural history/prognosis
  • Targeted management (anticipatory guidance, management changes, specific therapies)
  • Predictive testing of at-risk family members
  • Testing and exclusion of disease in siblings or other relatives
  • Recurrence risk assessment

Serving as a second-tier test for patients in whom previous genetic testing was negative.

Providing a potentially cost-effective alternative to establishing a molecular diagnosis compared to performing multiple independent molecular assays.

Specimen requirements

Whole Genome Sequencing: Ordering Checklist is required for all patients, and Informed Consent is required for New York clients. Fill out one form for the family and send with the specimens.

  • Specimen Type: Whole Blood
  • Patient Preparation: A previous bone marrow transplant from an allogenic donor will interfere with testing. Call 800-533-1710 for instructions for testing patients who have received a bone marrow transplant.


  • Lavender top (EDTA) or yellow top (ACD)


  • Any anticoagulant
  • Specimen Volume: 3 mL
  • Collection Instructions:
    1. Invert several times to mix blood.
    2. Send whole blood specimen in original tube. Do not aliquot.

Additional Information: If a cord blood specimen is received, MATCC / Maternal Cell Contamination, Molecular Analysis, Varies will be performed at an additional charge; maternal blood sample is required.

Performance information

Analytic time: 84 days

Days performed: Varies

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Barbara J. Toman

Barbara J. Toman is a Senior Communications Specialist at Mayo Clinic Laboratories. She is also the science writer for Mayo’s Neurosciences Update newsletter, which helps referring physicians to stay informed about Mayo’s treatment and research. Barbara has worked at Mayo Clinic since 2007. She enjoys international travel and cooking.