Banding in Genetic Disorders

Norm of Banding in Genetic Disorders

Cytogenic techniques with numerical designations map each chromosome for abnormalities.



44 autosomes + 2X chromosomes
Karyotype: 46,XX



44 autosomes + 1X and 1Y chromosomes
Karyotype: 46,XY


Usage of Banding in Genetic Disorders

Assists in the diagnosis of genetic and neoplastic disorders.


Description of Banding in Genetic Disorders

Banding techniques are used for chromosome identification. Human chromosomes are numbered in 23 pairs. Each chromosome pair has a unique pattern with intricate detail produced by different distributions of DNA in the chromosomes. Banding helps detect different regions of the same chromosome for use in identification of both the chromosome and the chromosomal abnormalities. R banding uses a reverse Giemsa stain called acridine orange, which produces reverse contrast to the light Q bands detected by quinacrine mustard and dark and light crossband G bands detected with trypsin and Giemsa stain. R dark bands are useful for observing the very dark ends of chromosomes. The chromosome count per cell and banded karyotype with interpretation is included in the testing.


Professional Considerations of Banding in Genetic Disorders

Consent form IS recommended.

  1. Tube: Green topped.



  1. Draw a 4-mL blood sample.


Postprocedure Care

  1. None.


Client and Family Teaching

  1. Results are normally available in 1–2 weeks.
  2. Refer the client with abnormal results for genetic counseling.


Factors That Affect Results

  1. Heparin in the specimen collection tube must be sodium heparin.


Other Data

  1. This method is used widely in European countries, especially France.
  2. See also Chromosome analysis — Blood .