aCGH Array CGH Array Comparative Genomic Hybridization Oligonucleotide Array Oligo Array Single Nucleotide Polymorphism (SNP) Array Whole Genome Array Microarray Molecular Karyotype OncoScan Congenital Array Constitutional Array Absence of Heterozygosity (AOH) Fetal Demise Miscarriage Pregnancy Loss Paraffin Embedded Tissue Array Paraffin Embedded POC Array
Hematoxylin and eosin stain review of the paraffin-embedded sample is performed to identify the area of fetal tissue prior to DNA extraction and microarray analysis. If additional FISH testing is requested, it will be performed at an additional charge.
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 a fresh specimen is submitted, the test will be cancelled and CMAPC / Chromosomal Microarray, Autopsy, Products of Conception, or Stillborn will be added and performed as the appropriate test.
Diagnosis of congenital copy number changes in products of conception, including aneuploidy (ie, trisomy or monosomy) and structural abnormalities
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 previously by other methods such as conventional chromosome and 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
A maternal blood sample is requested when ordering this test (see PPAP / Parental Sample Prep for Prenatal Microarray Testing). Testing will not be rejected if maternal blood is not received; however, the possibility of maternal cell contamination cannot be excluded. The PPAP test must be ordered under a different order number than the prenatal specimen.
A paternal blood sample is desired but not required (see PPAP / Parental Sample Prep for Prenatal Microarray Testing).
A reason for referral and pathology report are required in order for testing to be performed. Send information with specimen. Acceptable pathology reports include working drafts, preliminary pathology or surgical pathology reports.
This test does not detect balanced chromosome rearrangements such as Robertsonian or other reciprocal translocations, inversions, or balanced insertions.
This test is not designed to detect low-level mosaicism, although it can be detected in some cases.
This test does not detect point mutations, small deletions, or insertions below the resolution of this assay, or other types of mutations 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.
Copy number variants are classified based on known, predicted, or possible pathogenicity and reported with interpretive comments detailing their potential or known significance.
While many copy number changes observed by chromosomal microarray testing can readily be characterized as pathogenic or benign, there are limited data available to support definitive classification of a subset into either of these categories, making interpretation of these variants challenging. In these situations, a number of considerations are taken into account to help interpret results including the size and gene content of the imbalance, as well as whether the change is a deletion or duplication. Parental testing may also be necessary to further assess the potential pathogenicity of a copy number change. In such situations, the inheritance pattern and clinical and developmental history of the transmitting parent will be taken into consideration.
All copy number variants within the limit of detection classified as pathogenic or likely pathogenic will be reported regardless of size. This includes, but is not limited to, incidental findings currently recommended for reporting by the American College of Medical Genetics and Genomics (ACMG).(1) Copy number changes with unknown significance will be reported when at least one protein-coding gene is involved in a deletion greater than 1 megabase (Mb) or a duplication greater than 2 Mb.
The detection of excessive homozygosity may suggest the need to test for variants in genes associated with autosomal recessive disorders consistent with the patient's clinical presentation that are present in regions of homozygosity. Homozygosity will be reported when involving greater than 20% of the genome. Homozygosity involving the entire genome is indicative of a complete molar pregnancy.
The continual discovery of novel copy number variation and published clinical reports means that the interpretation of any given copy number change may evolve with increased scientific understanding.