aCGH

aCGH, or array Comparative Genomic Hybridization, is a molecular cytogenetic technique used to detect and map copy number variations (CNVs) across the genome. CNVs include deletions, duplications, and amplifications of DNA segments that can be associated with genetic disorders, cancers, and developmental abnormalities.

The method involves hybridizing differentially labeled DNA samples—typically test and reference DNA—to a microarray containing thousands of DNA probes. The sample DNA is labeled with one fluorescent dye, while the reference is labeled with another. After hybridization, the microarray is scanned to measure the fluorescence intensity ratios at each probe site. Variations in these ratios indicate gains or losses of genetic material in the test sample relative to the reference.

aCGH is widely used in clinical genetics and research for its ability to identify submicroscopic chromosomal imbalances that are not detectable by traditional karyotyping. It provides high-resolution genome-wide analysis, often at the kilobase level, facilitating diagnosis of conditions like autism spectrum disorders, congenital anomalies, and certain cancers.

Limitations of aCGH include its inability to detect balanced chromosomal rearrangements, such as translocations or inversions, and its dependency on the availability of a suitable reference genome. Variants of aCGH, such as array-based tests with enhanced resolution or targeted arrays, are continuously evolving to improve diagnostic accuracy.

Overall, aCGH represents a vital tool in genomic analysis, offering detailed insights into structural genomic variations that underpin various genetic and acquired conditions.