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Test Code LAB1230489 Array Comparative Genomic Hybridization (aCGH), Prenatal

Test Name Alias

Maternal Cell Contamination | Microarray, Prenatal W/Mother's Blood | chromosome (CGH) | chromosomal |

Panel Information

MICROARRAY, PRENATAL W/ MOTHERS BLOOD - Panel Summary

LAB1230488 Array Comparative Genomic Hybridization (aCGH), Prenatal
LAB1230490 Maternal Cell Contamination

Clinical Information

Chromosomal microarray (array comparative genomic hybridization, aCGH) analysis is useful for detecting clinically significant copy number abnormalities in patients with phenotypic features suggestive of a congenital chromosome rearrangement. Microarray testing permits a whole genome survey at very high resolution and is currently recommended by the American College of Medical Genetics as a first-tier test for certain patients.

 

The SNP (single nucleotide polymorphism) portion of the microarray allows detection of regions with absence of heterozygosity (AOH). Long continuous stretches showing AOH indicate findings of potential clinical significance related to two classes of disorders:

1.Those involving imprinted genomic regions (resulting from uniparental disomy or UPD) and

2.Recessive disorders (resulting from UPD or identity by descent).

 

The SNP microarray may provide results consistent with consanguinity (i.e. the parents are closely related). Pre-test counseling should address this issue. The current platform is the GGXChip + SNP v1.0 4-plex - CGH array (manufactured by Agilent Technologies) which contains ~108,000 oligonucleotide copy number probes and ~60,000 SNP probes. The oligo probes cover every region known to be involved in cytogenetic abnormalities, including over 255 recognized genetic syndromes, over 980 gene regions of functional significance in human development, the pericentromeric regions, and the subtelomeres.

 

The SNP probes have an average spacing of ~49 kb. This spacing permits detection of AOH with an effective resolution of approximately 5-10 Mb across the genome.

 

Fluorescence in situ hybridization (FISH) analysis may be performed for follow-up testing, if deemed appropriate.  Additionally, testing of parents may be necessary in some cases to clarify a finding of unknown significance.

 

Testing Limitations:  Chromosome Microarray Analysis cannot detect:

1.  Balanced chromosome rearrangements such as translocations, balanced insertions, or inversions.

2.  Low level mosaicism.

3.  An abnormality in a region not represented on the array.

 

Collection Instructions

 

REQUIRED: Specimen Collection: Peripheral Blood, venous

Container(s): Lavender top (EDTA)

Preferred volume to collect: 3 mL 

Minimum volume to collect: 1 mL 

Capillary Acceptable: Yes

Microtainer Acceptable: Yes

 

Collection Instructions:

  • Collect 3 - 5 mL of maternal peripheral blood in one Lavender-top EDTA tube with each specimen type for maternal cell contamination studies, if needed
  • After collection, gently invert tube 8-10 times.

 

Submit one of the following specimen types:

Specimen Collection: Amniotic Fluid

Container(s): 15 mL sterile tubes

Volume to collect: 20 - 30 mL

 

Collection Instructions:

  • Collect 20 - 30 mL amniotic fluid into sterile 15 mL centrifuge tubes.

 

Specimen Collection: Chorionic Villus Sample

Container(s): 15 mL sterile tubes containing tissue culture transport medium

Volume to collect: 10 mg chorionic villus tissue

 

Collection Instructions:

  • Collect 10 mg chorionic villus tissue and place into sterile 15 mL centrifuge tube containing tissue culture transport medium

Processing Instructions (Laboratory, Outpatient or Off-site collection)

Processed Specimen: Peripheral blood, Amniotic fluid or Chorionic Villus sample

Spin: No

Aliquot: No

 

Processing Instructions:

  • Do not freeze specimen
  • Store all specimen types at room temperature (ambient, 20-26°C or 68-78.8°F)

Transport Temperature: Ambient

  • For delays in transport (>24 hours from the time of collection), refrigerate (2-8°C or 36-46°F)

Rejection Criteria

  • Improperly labeled specimens
  • Frozen specimens
  • Cracked or compromised specimen tubes
  • Specimens received greater than 72 hours past the time of collection

Reflex Information

Please refer to the Reflex Guide

Specimen Stability

All specimen types:

Ambient: 24 hours

Refrigerated: 72 hours

 

Laboratory Retention: 2 weeks

Test Frequency

Microarray testing is performed weekly (or more often as the case load requires).

Expected turn-around time (TAT) approximately 7 - 10 days after chromosome final report is issued.

Reference Range

An interpretative report will be provided.

Performing Department

CYTOGENETICS

Performing Department Laboratory Location

Spectrum Health Advanced Technology Laboratory (ATL), Grand Rapids, MI

Methodology

Array comparative genomic hybridization (aCGH)

CPT

81229-LAB-ANALYS CYTOGEN MICRA

81265-Maternal Cell contamination (if needed)

 

Insurance authorization is required in most cases. Please submit authorization number with order.

CDM Code

4148385

Epic Test ID

1230102352

Reviewed Date

8/15/2018