Array Comparative Genome Hybridization (array CGH) compares the patient’s genome against a reference genome and identifies the differences between the two genomes. These differences are recognized as genomic imbalance (for example a deletion/loss or a duplication/gain) in the patient. Array CGH is capable of giving quantitative results.
In the array CGH we expect to detect some small DNA segments that are present in more or less than two copies. Some of these are Copy Number Variation (CNV). A CNV is a DNA segment (minimum 1000 base pairs) that is present in varying number of copies in different individuals. They are in most case harmless but can in rare cases be associated with a disease.
Figure 1:Micro Array Scanner
Advantage of a standard array CGH compared with a conventional chromosome examination
Analysis of whole genome in single experiment.
Higher resolution than conventional CGH.
Limitation
- Inability to detect mosaicism, balanced chromosomal translocation, inversion and whole-genome ploidy changes.