A guide to the Chromosome Microarray Analysis
1. What is a CMA?
CMA is a novel method of analyzing chromosomes for a large number of genetic disorders. With a single test, CMA can detect genetic abnormalities on all chromosomes simultaneously. CMA has much higher sensitivity than the older chromosome test called Karyotype.
2. What does the CMA test for?
CMA can detect genomic errors for each of the disorders that are usually identified by karyotype analysis, including Down Syndrome, trisomy 13, trisomy 18, sex chromosomal abnormalities and other rare genetic disorders reported to be associated with mental retardation and/or physical problems. Additionally it can test for all known microdeletion/duplicate syndromes, as well as the pericentromeric and subtelomere regions.
3. What are the benefits of the test?
CMA is more sensitive than older methods of chromosomal anaylsis, and is able to detect abnormalities that would have not been identified by karyotype analysis. If an abnormality is found, the results may provide important information that could help guide medical decisions.
4. What is needed to perform a CMA test?
A small sample of blood (10cc for an adult and 4cc for a child) is the specimen most commonly submitted for analysis. Blood from both parents may also be requested. CMA can also be performed from tissue samples (placenta, cord, products of conception and skin biopsies). Amniotic fluid or a choionic villus sample (CVS) are used in the prenatal setting.
5. How much does the test cost? Will insurance pay for the test?
For information on cost, please contact the billing department. If your insurance requires it we will run a prior authorization in order to determine coverage. Insurance coverage is determined by the insurance company and depends on individual policy limitations and medical indications.
6. What are the limitations of the test?
CMA is a new and sensitive test. it is possible that the test will detect a genetic abnormality for which there is currently very little medical information available to predict the type of clinical problems that may develop in an individual. While the test is very accurate, not every geonomic abnormality (genetic defect) can be detected by a test. For some conditions, geonomic gains or losses at a particular locus may represent only a certain percentage of the genetic changes associated with that given disorder. For instance, in some disorders, 99% of the cases may be detected by the test, while for others the detection rate may be 70% or less. There are some changes in chromosomes that CMA can not detect such as balanced rearrangements or changes in regions not covered by the array. Many of these can be detected by karyotype analysis which can be run as a supplemental test.
7. How do I learn more about the CMA test?
If additional information is desired about this test, talk to your physician or call our office at 260-482-3886.