Bandningen

Bandningen is a term used in cytogenetics to describe the process of creating banding patterns on chromosomes to enable their identification and analysis. By applying specific stains to chromosomes in metaphase, researchers obtain alternating dark and light bands that reflect differences in DNA content, replication timing, and chromatin structure. The concept is widely used in Scandinavian literature under the form of bandning, with the word evolving into a general label for this family of techniques.

The main banding techniques include G-banding, Q-banding, R-banding and C-banding. G-banding uses a Giemsa stain to produce characteristic dark and light regions that correlate with GC content and gene density. Q-banding relies on fluorescence with a quinacrine stain for a similar banding pattern. R-banding is the reverse of G-banding, obtained after different pretreatments, while C-banding selectively highlights constitutive heterochromatin around centromeres. Each method provides a reproducible map of chromosomal structure that facilitates identification of individual chromosomes and detection of abnormalities.

Applications of banding include routine karyotyping, diagnosis of chromosomal rearrangements (such as translocations, deletions, duplications, and inversions), and research in genetics and evolutionary biology. The procedure generally requires a tissue sample (for example blood or bone marrow), culture to obtain metaphase cells, slide preparation, staining, and careful microscopic analysis to interpret the banding pattern.

Limitations of traditional banding lie in its limited resolution, typically at the megabase scale, and reliance on chromosome quality. Modern methods such as fluorescence in situ hybridization (FISH), array comparative genomic hybridization (array-CGH), and sequencing provide higher resolution and complementary data. See also cytogenetics, karyotyping, and chromosomal banding techniques.