Useful For: Prenatal diagnosis of copy number changes (gains or losses) across the entire genome Diagnosing chromosomal causes for fetal death Determining recurrence risk of future pregnancy losses Determining the size, precise breakpoints, gene content, and any unappreciated complexity of abnormalities detected by other methods such as conventional chromosome and fluorescence in situ hybridization (FISH) studies Determining if apparently balanced abnormalities identified by previous conventional chromosome studies have cryptic imbalances, since a proportion of such rearrangements that appear balanced at the resolution of a chromosome study are actually unbalanced when analyzed by higher-resolution chromosomal microarray Assessing regions of homozygosity related to uniparental disomy or identical by descent.
This test does not detect balanced chromosome rearrangements such as Robertsonian or other reciprocal translocations, inversions, or balanced insertions.
A maternal blood sample is requested when ordering this test, see PPAP / Parental Sample Prep for Prenatal Microarray Testing. The PPAP test must be ordered under a different order number than the prenatal specimen.
Maternal cell contamination (MCC) testing will be performed at no additional charge on the maternal blood and fetal tissue to rule out the presence of maternal cells in the product of conception sample. Testing will not be rejected if maternal blood is not received; however, the possibility of maternal cell contamination cannot be excluded. A paternal blood sample is desired but not required, see PPAP / Parental Sample Prep for Prenatal Microarray Testing. If an insufficient sample is received or MCC is identified in the prenatal sample, microarray testing will be performed on cultured material.
CMAPC code is for fresh tissue specimens in RPMI CMAMT code is for tissue block specimens
Specimen Requirements
Specimen Type: Products of conception or stillbirth Supplies: Hank's Solution (T132) Container/Tube: Sterile container with sterile Hank's solution, Ringer's solution, or normal saline Specimen Volume: 1 cm(3) of placenta (including 50-mg chorionic villi) and 1 cm(3) biopsy specimen of muscle/fascia from the thigh Collection Instructions: 1. Attempt to identify and send only fetal tissue for analysis. 2. If a fetus cannot be specifically identified, collect 50-mg villus material or tissue that appears to be of fetal origin. 3. If multiple specimen types are sent, send each specimen in a separate container. Multiple specimens received (eg, placenta and fetal thigh) will be ordered under 1 test. All specimens will be processed separately. Additional Information: 1. Do not send entire fetus. 2. While fresher specimens prepared as described above are preferred, we can attempt analysis on specimens that have been in less-than-ideal conditions.
Specimen Type: Chorionic villus Supplies: CVS Media (RPMI) and Small Dish (T095) Container/Tube: 15-mL tube containing 15 mL of transport media Specimen Volume: 50 mg Collection Instructions: 1. Collect chorionic villus specimen (CVS) by transabdominal or transcervical method. 2. Transfer CVS to a Petri dish containing transport medium (Such as CVS Media [RPMI] and Small Dish). 3. Using a stereomicroscope and sterile forceps, assess the quality and quantity of villi and remove any blood clots and maternal decidua.
Specimen Type: Tissue Container/Tube: Formalin-fixed, paraffin-embedded block containing fetal or placental (including chorionic villi) tissue. Additional Information: A pathology report and reason for referral must be submitted with each specimen. The laboratory will not reject testing if this information is not provided, but appropriate testing and interpretation may be compromised or delayed.
Specimen Type: Slides Specimen Volume: 6 Consecutive, unstained, 5-micron-thick sections placed on positively charged slides and 1 hematoxylin and eosin-stained slide.
Minimum Sample Volume
Chorionic villus: 10 mg Muscle-fascia: 1 cm(3)
Required Information
Necessary Information 1. Provide a reason for referral with each specimen. The laboratory will not reject testing if this information is not provided, but appropriate testing and interpretation may be compromised or delayed. 2. Notify the laboratory if the pregnancy involves an egg donor or gestational carrier.
Stability
Ambient (preferred), refrigerated
Limitations
This test does not detect all types and instances of uniparental disomy. This test is not designed to detect low-level mosaicism, although it can be detected in some cases. This test does not detect point alterations, small deletions, or insertions below the resolution of this assay, or other types of variants such as epigenetic changes. The results of this test may reveal incidental findings unrelated to the original reason for referral. In such cases, studies of additional family members may be required to help interpret the results.
Methodology
DNA extracted from autopsy, products of conception, or stillbirth samples is labeled and hybridized to the microarray. Following hybridization, the microarray is scanned, and the intensity of signals is measured and compared to a reference data set. These data are used to determine copy number changes and regions of excess homozygosity. Chromosomal microarray data alone does not provide information about the structural nature of an imbalance and some abnormal results may be characterized by fluorescence in situ hybridization, limited chromosome analysis, or additional techniques.
Estimated TAT
22 - 31 Days
Testing Schedule
Monday - Friday
Retention
Any identifiable fetal tissue (eg, skin, muscle) is held until the completion of testing and is eventually cremated on a quarterly basis. All other tissue (eg, placenta, chorionic villus) is discarded at the time results are reported.
Slides and H and E-stained slide used for analysis are retained by the laboratory. Client provided paraffin blocks and extra unstained slides (if provided) will be returned after testing is complete.