Microarray Testing (Chromosomal Microarray Analysis, CMA)

What is Microarray?

Microarray is an advanced molecular genetic technology in which biological molecules, such as DNA (and sometimes proteins), are immobilized on a solid surface—glass, plastic, or silicon chips—consisting of thousands of microscopic spots.

Microarray testing is also referred to as:
• Chromosomal microarray
• Whole-genome microarray
• Array-based comparative genomic hybridization (aCGH)
• SNP array

Each spot on the chip contains a predefined DNA probe sequence, usually 20–100 nucleotides in length. DNA extracted from the patient’s blood, saliva, or tissue is compared to these probes.

This allows the detection of:
• Genetic variations
• Loss or gain of chromosomal regions
• Submicroscopic chromosomal abnormalities not visible under a microscope

What Does Microarray Testing Detect?

Microarray testing can identify numerous medical conditions associated with chromosomal abnormalities:

• Deletion — loss of a small chromosomal segment
• Duplication — addition of a copy of a chromosomal segment
• Uniparental disomy (UPD) — both chromosomes of a pair are inherited from one parent
• Long stretches of homozygosity — large chromosomal regions with identical genetic material

Why Perform a Microarray Test?

• To determine the genetic cause of a condition and refine the diagnosis
• To assess the risk of passing genetic changes to children
• For preconception or prenatal assessment of hereditary disease risk
• To detect small chromosomal changes that are not revealed by standard karyotyping

Advantages of Microarray Testing

• High accuracy
• Comprehensive genomic coverage
• Especially useful for detecting developmental delays, congenital anomalies, and previously unexplained genetic disorders