Whole Exome Sequencing – DUO (Proband), Products of Conception (POC)
Use
WES is currently intended for use by patients suspected to have a genetic disorder. While the test is most frequently ordered for patients who have been unable to obtain a definitive diagnosis through traditional genetic testing, physicians may opt to initiate whole exome sequencing earlier in the diagnostic pathway. An initial workup using whole exome sequencing may be especially useful when a multigene testing approach is desired but would be prohibitively time-consuming, or when a known genetic disorder is suspected but testing for the genes of interest is not available. Patients with atypical presentation of a suspected syndrome may be candidates for exome sequencing. While patients can be of any age, many of the patients with the most pressing need for exome-wide interpretation are children with serious childhood genetic diseases. TRIO testing consists of a proband or patient sample, and both biological parents. In the case both parents are not available for testing, up to two family member samples are also accepted. TRIOs are preferred for better diagnostic sensitivity.
Special Instructions
All Whole Exome test orders require prior authorization review. WES is not offered for ongoing pregnancies and requires maternal cell contamination (MCC) testing for fetal samples. WES testing starts post-MCC analysis completion. If MCC is detected, WES is canceled. Maternal blood must be submitted with a separate requisition. Contact genetic coordinators at 800-345-4363 before submitting fetal samples.
Limitations
This test is not FDA-approved. WES has limited ability to capture quality sequence across the genome. Negative results do not exclude a genetic cause. It detects some mtDNA variants but not low level heteroplasmic, large deletions or depletions. Cannot detect mosaicism, CNVs, trinucleotide repeats, epigenetic effects, or large chromosomal rearrangements. It struggles with repetitive regions and may miss insertions/deletions. Findings may not impact management or outcomes.
Methodology
NGS (WES)
Biomarkers
LOINC Codes
- 86205-2
- 86205-2
- 56850-1
Result Turnaround Time
28-42 days
Related Documents
For more information, please review the documents below
Specimen
Body Fluid
Volume
10-15 mL
Minimum Volume
5 mL
Container
Sterile plastic conical tube or two T-25 flasks
Collection Instructions
Flasks should be completely filled with media and cells should be ~90% confluent. If product of conception, use a sterile tube with Ringer's lactate, Hanks' solution, or Labcorp medium.
Storage Instructions
Sample should be shipped in an insulated container at room temperature or refrigerated.
Causes for Rejection
Flasks insufficiently filled; contamination; formalin-fixed paraffin-embedded tissue; tissue is not fetal in origin
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 2 - 3 days |
| Refrigerated | 2 - 3 days |
| Frozen | Do not freeze. |