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Test Code LAB3308 Array Comparative Genomic Hybridization (aCGH), Constitutional

Test Name Alias

Microarray, chromosome (CGH), chromosomal microarray | 221

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 CytoScanHD solution (manufactured by Affymetrix).  The CytoScan HD is based on the independent analysis of two types of molecular markers:  1.7 million oligonucleotide probes and 750,000 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.

 

 

Collection Instructions

Specimen Collection: Peripheral Blood

 

Container(s): Lavender top (EDTA)

Preferred volume to collect: 6 mL 

Minimum volume to collect: 2 mL 

Neonate volume to collect: 1 mL 

 

Collection Instructions:

  • After collection, gently invert tube 8-10 times.

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

Processed Specimen: Whole Blood

Spin: N

Aliquot: N

 

Processing Instructions:

  • Keep whole blood at room temperature.

Transport Temperature: Ambient

Specimen Stability

Ambient: 3 days (beyond 3 days, specimen viability will be determined by Cytogentics Lab)

Laboratory Retention: Primary specimens 4 weeks; isolated DNA retained greater than 1 year

Test Frequency

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

Expected turn-around time (TAT) approximately 10 to 14 days.

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

 

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

CDM Code

4148385

Epic Test ID

1230100939

Interface Order Alias

11551

Interface Information

Order: 11551 - Microarray, chromosomal (CGH)

Result: 22539 - Cytogenetics Request

Questions: Other relevant history? [full text]

Reviewed Date

4/22/2019