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HelpComprehensive Carrier Screen (Inheritest)
Specimen and Container/Tube
Specimen Type: Whole blood
Preferred Specimen: lavender-top (EDTA)
Other Acceptable specimens: Yellow-top (ACD-A) tube
Specimen Stability
Whole blood: 4 days at room temperature or 4°C
Collection Instructions
Collect blood according to the standard laboratory collection procedures.
Specimen Handling and Transport Instructions
Maintain specimen at room temperature
Clinical Indications
Technologies used do not detect germline mosaicism and do not rule out the presence of large chromosomal aberrations including rearrangements and gene fusions, or variants in regions or genes not included in this test, or possible inter/intragenic interactions between variants or repeat expansions.
Variant classification and/or interpretation may change over time if more information becomes available. False positive or false negative results may occur for reasons that include: rare genetic variants, sex chromosome abnormalities, pseudogene interference, blood transfusions, bone marrow transplantation, somatic or tissue-specific mosaicism, mislabeled samples or erroneous representation of family relationships.
Methodology
Next Generation Sequencing: Identifies genetic variants, including small nucleotide variants (SNVs), insertions, deletions and copy number variants (CNVs).
Spinal muscular atrophy (SMA): Copy number assessment of SMN1 exon 7 by quantitative polymerase chain reaction (qPCR). For carrier screening, when two copies of SMN1 are detected, allelic discrimination qPCR targeting c.*3+80T>G in SMN1 is performed. The presence or absence of c.*3+80T>G correlates with an increased or decreased risk, respectively, of being a silent carrier (2+0).
Fragile X syndrome: Polymerase chain reaction (PCR) followed by capillary electrophoresis, with reflex to AGG interruption analysis and methylation PCR analysis for positive samples.
Additional Information
Males are not tested for x-linked disorders, including fragile X syndrome.
Test orders must include an attestation that the provider has the patient's informed consent for genetic testing.
Turnaround Time
14 - 21 days (In some cases, additional time may be required for confirmatory or reflex tests.)
Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Volume
Preferred Volume: 8.5 mL whole blood
Minimum Volume: 3 mL whole blood
Rejection Criteria
Frozen or hemolyzed specimen; quantity not sufficient for analysis; improper container or blood specimens more than four days post draw