Easy-to-collect blood is the most used cell source in human cytogenetics.

 

Karyotyping of blood cells is an important tool in modern human cytogenetics, providing information on chromosomal abnormalities, their frequency in the population, and the relationship between specific chromosomal abnormalities and phenotypic effects.

 

By culturing peripheral blood cells in the presence of mitogens, cytogeneticists obtain cultures that are used for chromosomal analysis.

 

The time of collection of the cells is determined so as to find as many cells as possible at the metaphase stage. The cells are then fixed and spread on a slide. Chromosomes are stained with various dyes, usually Giemsa (G-band and R-band), which produce banding patterns on chromosomes with a resolution of 400-650 bands per haploid lot of chromosomes. Chromosomes and their bands are then examined under a microscope for abnormalities, such as loss or gain of whole chromosomes, translocations of an entire arm (or part of it) from one chromosome to another or more subtle changes in patterns of bands associated with various genetic syndromes.