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Test ID: CGH
Array Comparative Genomic Hybridization (aCGH), Whole Genome, Constitutional

Method Description Describes how the test is performed and provides a method-specific reference

DNA extracted from the patient's peripheral blood and a control DNA sample are labeled with contrasting fluorescent dyes. The patient and control DNA samples are mixed and hybridized to the microarray. Following hybridization, the microarray is scanned and an intensity ratio profile of the fluorescent dye signals is created. The profiles are interpreted to detect copy number changes as compared to the normal control. The microarray is composed of 180,000 (180K) unique oligonucleotide probes spaced at a minimum of 25 kilobases across the entire genome.  In addition, approximately 500 regions throughout the genome contain higher-density, targeted oligonucleotide probe coverage of 1 probe per 5 kilobases. These targeted regions include the pericentromeric and subtelomeric regions of each chromosome, chromosomal regions known to be associated with specific clinical phenotypes or syndromes, and specific genes implicated in developmental abnormalities. Array CGH data alone does not provide information about the structural nature of an imbalance, thus, whenever possible, all abnormal results are characterized by additional techniques. For large deletions and duplications that are cytogenetically visible, G-banded chromosome analysis is used. FISH testing is typically employed for smaller abnormalities. (unpublished Mayo data)

Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.

Monday through Thursday: 6:30 a.m. - 1:30 a.m.; Friday: 6:30 a.m. - 5:00 p.m.

Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.

8 days

Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result

3 weeks

Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

Indefinitely

Performing Laboratory Location The location of the laboratory that performs the test

Rochester