Chromosomal Microarray, Prenatal
Label Mnemonic: CMAPD
Epic Lab Code: LAB8136
Downtime Form: A-1a Miscellaneous Request
Commercial Mail-out Laboratory
5231 RCP
Amniotic Fluid or CVS
Specimen Instructions:
Collection Instructions for Amniotic Fluid:
1. Optimal timing for specimen collection is during 14 to 18 weeks of gestation, but specimens collected at other weeks of gestation are also accepted. Provide gestational age at the time of amniocentesis.
2. Discard the first 2 mL of amniotic fluid.

Collection Instructions for Chorionic villi:
1. Collect specimen by the transabdominal or transcervical method.
2. Transfer chorionic villi to a Petri dish containing transport medium.
3. Using a stereomicroscope and sterile forceps, assess the quality and quantity of the villi and remove any blood clots and maternal decidua.
Submit only ONE of the following preferred specimens:
20-30 mL Amniotic Fluid
20-30 mg Chorionic villi
Absolute Minimum: 5 mL
Rejection Criteria:
Bloody specimens are undesirable.
Turn Around Time:
10 days upon receipt at reference laboratory
Reference Range:
An interpretive report will be provided.
Please print, complete and submit the Chromosomal Microarray Prenatal Patient Information and the Informed Consent for Genetic Testing from Mayo Medical Laboratories with the specimen and the A-1a Miscellaneous Request or Epic Req.

Useful for:
Prenatal diagnosis of copy number changes (gains or losses) across the entire genome.

Determining the size, precise breakpoints, gene content, and any unappreciated complexity of abnormalities detected 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.

Assessing regions of homozygosity related to uniparental disomy or identity by descent.

This test does not detect balanced chromosome rearrangements such as Robertsonian or other reciprocal translocations, inversions, or balanced insertions. These abnormalities may be identified by chromosome analysis.

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 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 be of uncertain clinical significance. In such cases, studies of additional family members may be required to help interpret the results.
Chromosomal Microarray (CMA) using Affymetrix Cytoscan HD
CPT Code: