Prenatal Exome Sequencing-XL – Trio Analysis
Key Information
Lab:
TAT:
21 days
Price:
Contact Lab
CPT Code(s):
81415, 81416x2
Test Code:
DPX3
Prenatal Samples Accepted
Prenatal Exome Sequencing-XL – Trio Analysis
Prenatal Exome Sequencing-XL (PES-XL) Trio Analysis (maternal, paternal, and fetal sample) is available for patients with abnormal ultrasound findings. This is a phenotype-driven analysis where only pathogenic and likely pathogenic variants related to the reported clinical features will be included in the prenatal report.
Maternal Cell Contamination (MCC) is required for this test, and cell culture may be necessary. A preliminary report will be available at 21 days from sample receipt, if requested. The final report will be available within 3-5 weeks. If a cell culture is needed, turnaround time may be an additional 2-4 weeks.
Reanalysis may be requested at no additional charge after the baby is born, and any new medical information should be reported to the lab upon request for reanalysis. A new consent and test requisition form will be required for reanalysis. Any changes suspected of causing the concerns identified during pregnancy will require a postnatal sample for confirmation.
Technical Information
PES-XL detects single nucleotide variants (SNVs) within exonic regions, intronic regions, promoters, and 3’-UTRs. SNVs are only detected in intergenic regions if the variant has been previously reported. PES-XL will detect copy number variants (CNVs). Disease-associated sequence variants in the mitochondrial genome will also be reported. If a causative variant is identified during either SNV or CNV analysis, the other analysis may not be performed. However, the clinical team will be given the option to proceed with the full analysis and it will also be noted in the final report. PES-XL will not detect trinucleotide repeat expansions, methylation abnormalities, balanced rearrangements, and some small exonic-level copy number changes. The following will not be reported for PES-XL: variants of uncertain clinical significance, variants in new genes where the function of the gene is currently unknown, secondary findings, benign variants, and carrier status. If requested, the postnatal reanalysis may include additional variants in novel genes and variants of uncertain significance as well as the option to report secondary findings.
Specimen Requirements
Amniotic Fluid: Direct amniotic fluid will be accepted for analysis given there is sufficient volume for back-up culture to be established. A back-up culture at a reference lab OR Greenwood lab is required. Additional charges may apply if cell culture is required after receipt of the sample. If sending direct fluid for PWES-XL only, 10-20 ml of amniotic fluid is requested. Chromosome studies will require an additional 10-15 ml of fluid. Cultured amniocytes: 2x T25 confluent flasks Maternal Sample: A maternal sample is required. Accepted maternal sample types include whole blood in an EDTA/lavender top tube (4-5 ml), saliva/saliva swab, or extracted DNA (≥ 3 μg). For CVS sample, please contact the laboratory to determine if sample can be accepted for PWES-XL. If a postnatal reanalysis or targeted analysis is requested, an additional blood sample after delivery may be requested.
Prenatal Testing Information
Prenatal diagnosis is available if one or more ultrasound findings are identified. Additional fees for cell culture and maternal cell contamination may apply. Maternal cell contamination studies are required for all prenatal molecular tests.
Prenatal Specimen Requirements
Amniotic Fluid: Direct amniotic fluid will be accepted for analysis given there is sufficient volume for back-up culture to be established. A back-up culture at a reference lab OR Greenwood lab is required. Additional charges may apply if cell culture is required after receipt of the sample. If sending direct fluid for molecular analysis only, 10-20 ml of amniotic fluid is requested. Chromosome studies will require an additional 10-15 ml of fluid.
Chorionic Villi Sample (CVS): 10-50 mg of chorionic villi is requested in a sterile tube with CVS media. Direct testing on CVS is not available; an additional 1-3 weeks may be needed for cultures to grow.
Cultured amniocytes/CVS: 2x T25 confluent flasks
Maternal Sample: A maternal sample is required. Accepted maternal sample types include whole blood, saliva/saliva swab, and extracted DNA. Collect 3-4ml of whole blood in an EDTA (lavender top) tube. Send approximately 5µg of extracted DNA at a requested concentration of 90-130 ng/µl.
Saliva samples must be submitted in an approved saliva kit.
Blood and saliva kits are available by request.
Prenatal Transport Instructions
Amniotic fluid should be kept at room temperature; do not freeze or refrigerate. Specimen should be sent by courier or overnight mail to arrive at the laboratory the next day. FedEx is preferred.
CVS and cultured amniocytes should be kept at room temperature; do not freeze or refrigerate. Specimen should be sent by courier or overnight mail to arrive at the laboratory the next day. FedEx is preferred.
The blood specimen should be kept at room temperature and delivered via overnight shipping. FedEx is preferred. If shipment is delayed by one or two days, the specimen should be refrigerated and shipped at room temperature. Do not freeze the specimen. Please contact the lab with any questions.
Extracted DNA should be sent at room temperature via overnight delivery.
Saliva is stable at room temperature and can be delivered via overnight or ground shipping.
Associated Tests
Connect With Our Experts
Call 1-800-473-9411 to speak with our team of laboratory genetic counselors for questions or additional information.
Robin Fletcher, MS, CGC
Falecia Thomas, MS, CGC
Alex Finley, MS, CGC