Comparative genomic hybridization (CGH) or Chromosomal
Microarray Analysis (CMA) is a recent technology development
that allows for an entire genome to be analyzed in more
detail than is possible using conventional cytogenetics.
Conventional Cytogenetics can detect changes in the amount
of DNA >5Mb. Convential Molecular genetic techniques
allow us to detect changes of as little as one base pair
of the DNA sequence, however the target area or gene
has to be identified in advance to make this possible.
Microarrays combine the assets of both conventional molecular
and cytogenetics to allow a whole genome screen to be
performed but with the ability to detect changes smaller
than 5Mb. This allows for the exact boundaries of microduplications
and/or microdeletions to be detected. In turn, the specific
genes in these segments can be identified, which may
be of clinical significance.
DNA from the test sample and a control sample are labeled with fluorescent dyes and hybridized to the oligos. Results are analyzed using quantitative imaging methods and analytical software is used to assist in identifying each targeted-DNA sequence as loss of copy number, gain of copy number, or normal copy number. This technology has been validated on patients with known microdeletions/duplications and other unbalanced karyotypes detected by traditional cytogenetic methods. CMA will not detect low level mosaicism, balanced translocations, or inversions.
CMA may be ordered for anyone with dysmorphic features,
unexplained mental retardation/developmental delay,
congenital anomalies not specific to a genetic syndrome, seizures, speech delay, multiple miscarriages, tumor analysis to aid in diagnosis, and any patient with normal chromosome analysis.
Methodology: Comparative Genomic Hybridization analysis 400k probes
Purpose: Confirmation of Clinical Diagnosis
Test Requisition: Molecular Requisition-Refer to diagnosis list on page 2 before ordering
CPT Code: 81228 Cost: $1905.00
Turn-around-time: 28 days
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