CMA-Expanded and Limited Karyotype - Prenatal - Amniotic Fluid
Use
CMA-Expanded utilizes array-based comparative genomic hybridization (aCGH) and contains 400K oligonucleotides to offer exon-by-exon copy number analysis of over 1,700 genes. This test is recommended for providers and patients who want the highest level of detection possible for potential copy number changes during fetal evaluations. It may provide insights for individuals with abnormal prenatal ultrasound findings, positive serum screenings, or advanced maternal age, or a family history of chromosomal abnormalities. However, it is limited to detecting gains and losses of genomic material and will not identify balanced translocations, inversions, or specific gene point mutations.
Special Instructions
Parental samples are essential for detailed analysis and can assist in interpreting fetal results. If maternal blood is included, contamination studies are performed automatically. It is highly recommended to obtain signed CMA consent to facilitate smooth processing. Any notable results will prompt alerts regarding additional analyses such as uniparental disomy (UPD). It is crucial for parents to be informed about potential fees for specific studies as these may not be automatically included.
Limitations
Gains and losses less than 1000 kb will not be reported if no genes are present within their region. Gains less than 500kb will not be reported if they do not show clinical relevance. Additionally, gains associated with certain conditions, including mitochondrial genome changes or adult-onset disorders, will also not be reported. Although actionable findings may lead to reporting on specific genes as noted in the consent form, abnormal results associated with balanced translocations or rearrangements will not be addressed under this testing protocol. Clinicians are encouraged to review American College of Medical Genetics (ACMG) guidelines for comprehensive understanding of reporting limitations.
Methodology
Chromosomal / Cytogenetics (FISH)
Biomarkers
Result Turnaround Time
7-10 days
Related Documents
For more information, please review the documents below
Specimen
Amniotic Fluid (Fresh)
Volume
20-30 cc
Minimum Volume
20 cc
Container
two sterile 15 ml conical centrifuge tubes
Collection Instructions
Collect 20-30 cc of fluid. Discard the first 2 cc of fluid collected.
Causes for Rejection
Specimen cannot be frozen.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 48 hours |