CMA using Array Comparative Genomic Hybridization (aCGH) is available through the Medical Genetics Laboratories. The Medical Genetics Laboratories at Baylor College of Medicine was one of the first labs to offer CMA for clinical application, and we remain a leader in the implementation of new technology for CMA. With a single test, CMA will detect all of the disorders detected by chromosome analysis and multiple FISH tests, with the exception of balanced translocations and balanced inversions. Included in CMA are probes for all the known microdeletion/duplication syndromes, as well as the pericentromeric and subtelomeric regions. Subtelomeric evaluation is enhanced with CMA by using multiple oligos, covering approximately 10 Mb at each telomere. In addition to these targeted regions, the entire genome is covered with oligo clusters spaced at a minimum of 1 megabase throughout the 3000 megabase genome. Chromosomal Microarray Analysis is a major advance in genetic testing, assisting the clinician in the diagnosis of patients in which a genetic condition is suspected. Reasons for Referral:Chromosomal Microarray Analysis may be ordered for any patient with any suspicion of genomic imbalance: dysmorphic features, unexplained mental retardation/developmental delay, or multiple congenital anomalies. CMA is most appropriate for patients who are candidates for subtelomere FISH or multiple individual FISH tests. CMA is well suited to detect interstitial duplications that currently can be detected only by interphase FISH. Although the test can detect some deletions or duplications causing single gene or contiguous gene phenotypes (e.g., Pelizaeus-Merzbacher), other forms of testing must be used as appropriate. Patients found to have a deletion/duplication by CMA will have the finding confirmed using chromosome analysis and/or FISH at no additional cost. Testing Methodology:Chromosomal Microarray Analysis (105K Oligo Array) utilizes array-based comparative genomic hybridization (aCGH) with approximately 105,000 oligos corresponding to 3500-4000 known genomic locations attached to a glass slide. There is increased coverage at each region of interest. Genomic DNA from the test sample and a control sample are differentially labeled with fluorescent dye and hybridized to the oligos. Results are analyzed using quantitative imaging methods and analytical software to assist in identifying each targeted-DNA sequence as loss of copy number (deletion), gain of copy number (duplication) or normal copy number. This technology has been validated in our laboratory on many patients with known microdeletions/duplications and other unbalanced karyotypes detected by traditional cytogenetic methods. CMA is limited to detection of gain or loss of genomic material. It will not detect low level mosaicism, balanced translocations, inversions or point mutations that may be responsible for the clinical phenotype. Specimen Requirements:Blood in both EDTA (purple top) and
Na Heparin (Green top) tubes: Turnaround Time:7-10 days Shipping and Handling:Our recent collaboration with Athena Diagnostics
requires that samples be shipped to: **Questions concerning this collaboration may be directed to Medical Genetics Laboratories at 1-800-411-4363.
CPT Codes:For information on fees or CPT Codes for Prenatal CMA, please contact our Billing Office at 713-798-3295. Please contact our genetic counselors at 1-800-411-4363 prior to prenatal sample submission. Forms: >> 105K
Disorder List References:
1. Cheung SW, Shaw CA, Yu W, Li J, Ou Z, Patel A, Yatsenko SA, Cooper
ML, Furman P, Stankiewicz P, Lupski JR, Chinault AC, Beaudet AL (2005)
Development and validation of a CGH microarray for clinical cytogenetic
diagnosis. Genet. Med. 7:422-432. Test Code:8655 |