Microarray analysis/Array-CGH (Comparative Genomic Hybridization) is a relatively new genetic screening method that can be described as “high-resolution chromosome analysis.” It is used to identify and measure the activity of specific genes.
In the context of array CGH (= Comparative Genomic Hybridization), the entire genome is examined for copy number changes (deletions/ loss of a DNA sequence, duplications/ doubling of a specific sequence). In this process, it is not possible to make statements about a change in localization, whether an excess section of the genome has duplicated, or to detect a point mutation (gene mutation if only a single nucleic base is affected by the change), but only statements about copy number or, in individual cases, small deletions (loss of one or more base pair(s) of a DNA sequence) that are located in only a single gene.
Indications (areas of application)
- Clarification of a mental disability
- Facial dysmorphia (facial dysmorphia)
- Disorders from the autism spectrum
- Multiple malformations
The procedure
Material needed
- Heparin blood (minimum 1-2 ml)
Preparation of the patient
- Not necessary
Disruptive factors
- None known
The laboratory method
In a microarray (chip), different DNA probes that can bind to specific DNA sites on a chromosome are applied to defined fields on the test surface, which is called hybridization.
Array CGH (= Comparative Genomic Hybridization) involves a comparison of the patient’s DNA with a reference sample. The DNA of a healthy control person is labeled with a different fluorescent dye for this purpose. If the copy numbers of both samples match, a mixed color is obtained.
In other forms of microarray analysis, copy number deviations (small deletion or small duplication) are detected by different intensity of the fluorescence signal compared to the reference sample. The analysis is performed digitally for all methods.
