Editing Cytogenetics (section)

===Advent of banding techniques===
[[Image:NHGRI human male karyotype.png|thumb|right|250px|Micrographic [[Karyotype|karyogram]] of a human male.]]
[[File:Human karyotype with bands and sub-bands.png|thumb|Schematic [[Karyotype|karyogram]] of a human, with annotated [[Locus (genetics)|bands and sub-bands]] as used in the [[International System for Human Cytogenomic Nomenclature]] for [[chromosomal abnormalities]]. It shows dark and white regions on [[G banding]]. It shows 22 [[homologous chromosome]]s, both the male (XY) and female (XX) versions of the [[sex chromosome]] (bottom right), as well as the [[human mitochondrial genetics|mitochondrial genome]] (at bottom left). {{further|Karyotype}}]]

In the late 1960s, [[Torbjörn Oskar Caspersson|Torbjörn Caspersson]] developed a quinacrine fluorescent staining technique (Q-banding) which revealed unique banding patterns for each chromosome pair. This allowed chromosome pairs of otherwise equal size to be differentiated by distinct horizontal banding patterns. Banding patterns are now used to elucidate the breakpoints and constituent chromosomes involved in [[Chromosomal translocation|chromosome translocations]]. Deletions and inversions within an individual chromosome can also be identified and described more precisely using standardized banding nomenclature. G-banding (utilizing trypsin and Giemsa/ Wright stain) was concurrently developed in the early 1970s and allows visualization of banding patterns using a bright field microscope.{{cn|date=February 2024}}

Diagrams identifying the chromosomes based on the banding patterns are known as ''idiograms''. These maps became the basis for both prenatal and oncological fields to quickly move cytogenetics into the clinical lab where karyotyping allowed scientists to look for chromosomal alterations. Techniques were expanded to allow for culture of free [[amniocyte]]s recovered from [[amniotic fluid]], and elongation techniques for all culture types that allow for higher-resolution banding.{{cn|date=February 2024}}