Chromosomal microarray (CMA; formerly array CGH)

Chromosomal microarray analysis (CMA; formerly array CGH) compares a patient's entire genome with that of clinically unremarkable individuals for losses and gains in genetic material. The test can be applied prenatally to check the DNA of an unborn child for abnormalities.

What can be examined with CMA?

CMA can be used to detect the smallest losses and gains of chromosomal material (so-called microdeletions and duplications), which are below the light microscopic detection limit. Compared to conventional chromosome analysis, which has a resolution of 5 to 10 Mb, CMA can detect much smaller genomic imbalances (up to about 25 kb).

How does CMA work?

For the analysis, the DNA of the patient and that of a reference is labeled with different fluorescent dyes and hybridized with immobilized DNA fragments on a microarray. If there is genomic loss or gain in the patient sample, the hybridization ratio shifts.

When is CMA used?

Indications for CMA include

• developmental delays in children
• multiple congenital malformations
• Dysmorphia
• disorders from the autism spectrum
• prenatal ultrasound abnormalities

What are the limitations of CMA?

Balanced translocations or inversions, polyploidies, single nucleotide variants, epigenetic changes, and low-grade mosaics are inherently not detected by this method. In combination with other methods of our wide range of analyses, such as chromosome analysis, exome sequencing or methylation-sensitive MLPA, we can ensure comprehensive diagnostics.

German health insurance? Please note the following:

According to chapter 11.4 of the German EBM (number 11500), a chromosome analysis must be performed before CMA is performed.