What is Chromosomal Microarray?

The human body contains genetic information which scientists organize into structural units that they call chromosomes. Medical conditions such as birth defects and developmental delays and autism and other health issues emerge when chromosome genetic material undergoes either addition or deletion changes. Chromosomal Microarray uses advanced technology to provide expanded genetic testing by detecting both large and small chromosomal changes. CMA employs copy number probes along with SNP probes to identify minor chromosomal alterations which traditional tests fail to detect because they only examine entire chromosomal patterns (Karyotype).

When should Chromosomal Micro Array testing be performed?

The abnormal results from maternal blood tests during pregnancy indicated a higher probability of experiencing medical complications or congenital birth defects. The presence of an abnormality on ultrasound requires further testing because all genetic tests conducted up to this point showed normal results. Parents who have had a child with any medical condition that involves chromosomal changes should be tested. Recurrent pregnancy loss requires special testing.

Testing should be conducted for women who have reached advanced maternal age.

Advantages of Chromosomal Micro Array over Karyotyping:

CMA offers superior performance because an array can examine the genome at greater detail compared to traditional karyotyping which enables detection of more clinically important variations. The time it takes for results to become available after collecting prenatal samples presents a second important factor that needs evaluation. The time required to produce karyotype results currently stands at 1 to 2 weeks because scientists must culture cells before they can conduct their analysis. The direct isolation of DNA from most villus and amniotic fluid samples eliminates the need for cell cultures in MA. Cell culture becomes impossible during still-birth analysis because the required cells will not be available. The process of microarray scanning enables automated operations which require less time compared to the manual scanning procedure needed for karyotype slides. The process will take less time because turnaround times will be reduced.

Limitations of Chromosomal Micro Array:

The technology of microarray testing in prenatal applications faces limitations similar to those found in karyotyping and other testing methods. The most frequently mentioned limitation of CMA testing emerges because it cannot identify actual balanced translocations.

CMS testing cannot identify balanced chromosomal translocations. CMA testing does not detect every genetic disorder. CMS uses genetic mutation probes but some cases contain variants which necessitate using Parental CMA analysis (Using probe is made out of the specific mutated sequence in the parental DNA) to achieve precise diagnosis.

Genetic consultation enables healthcare professionals to proceed with testing while interpreting microarray analysis results. They may also identify additional genetic tests needed based on clinical findings and family history during the diagnostic process.

Microarray technology

Microarray technology allows the simultaneous examination of multiple genes through a single experimental process. Protein and peptide and glycan microarrays are gaining popularity through their increasing usage beyond the common DNA microarray application.

Structure of a DNA microarray The array displays samples as spots which have a maximum diameter of 200 micrometers. The array contains thousands of spots which are organized into rows and columns with each spot representing one gene. The spotted samples are called probes and they traditionally exist as materials which include glass slides and silicon-thin chips and nylon membranes.

Bead arrays are being used where the arrangement is comprised of microscopic polystyrene beads which each form a specific probe that serves as the basis for the arrangement. The orderly arrangement of spotted samples on a solid structure provides an easily determined location for each gene being analyzed. The location of the gene is then recorded onto a computer database.