chevron_rightChromosomal microarray analysis (CMA) is a high resolution, whole- genome screening technique that can identify most of the chromosomal imbalances detected by conventional cytogenetic analysis, as well as smaller sub-microscopic deletions and duplications that are referred to as copy-number variants (CNVs).
chevron_rightIt is able to detect changes as small as 5-10Kb in size - a resolution up to 1000 times higher than that of conventional karyotyping.
chevron_rightCNVs may cause a wide range of human disorders, including neurodevelopmental disorders and congenital anomalies such as cardiac defects.
chevron_rightCMA is recommended as the first-tier test in the postnatal evaluation of congenital abnormalities and neurodevelopmental disorders.
chevron_rightCMA is offered prenatally if one or more of the below indications are present:
chevron_rightAbnormal fetal ultrasound
chevron_rightAbnormal NIPT results indicated an increased risk of a chromosomally abnormal fetus.
Abnormal high-risk maternal serum screen
chevron_rightThe parents have a known chromosomal rearrangement, mosaicism or previous aneuploidies.
chevron_rightThe parents have had previous live births or stillbirths with chromosomal abnormalities
chevron_rightFetal congenital abnormalities detected with ultrasound or MRI that indicate a significant risk of an unbalanced chromosomal abnormality
chevron_rightApparently balanced inherited rearrangements in a fetus with congenital abnormalities.
chevron_rightApparently balanced de novo rearrangements identified by G-band analysis (karyotype) High risk pregnancies.
Workflow Of CMA
chevron_rightDNA from the sample is prepared and hybridized to a glass slide, on which a large number of molecular probes are arrayed; these probes consist of small segments of DNA corresponding to clinically significant (and potentially significant) regions covering the entire genome.
chevron_rightCurrently available microarrays contain more than two million unique DNA probes.
chevron_rightComputerized analysis of the hybridization pattern on the slide reveals the number of copies of DNA corresponding to each probe location.
Sample Requirement
chevron_right2-4mL (4mL preferred) of whole blood in EDTA
Limitations
chevron_rightMicroarray analysis detects unbalanced, but not balanced,chromosome abnormalities.
chevron_rightThe risk involved in screening for new diseases where the phenotypic spectrum is not fully understood before the ons et of screening.
chevron_rightRMicroarray analysis does not identify all genetic disorders. For instance, it does not detect sequence variation (e.g., point mutations), a major cause of dominant, recessive, and X-linked disorders.