What Is Karyotype Analysis?

Karyotype analysis is the systematic examination of the number and morphological characteristics of chromosomes in a cell or organism. In humans, a typical diploid somatic cell contains 46 chromosomes arranged into 23 pairs: 22 pairs of autosomes and one pair of sex chromosomes.

A conventional karyotype is generally prepared from cells arrested during metaphase, when chromosomes are sufficiently condensed for visualization. The chromosomes are photographed, identified, and arranged into homologous pairs according to their size, centromere position, and characteristic banding patterns.

A standard human karyotype may be represented as 46,XX or 46,XY. These notations describe typical chromosome complements associated with female and male chromosomal patterns, respectively, although chromosome composition and biological sex development can be more complex.

Karyotype analysis provides a broad overview of chromosome architecture. However, it does not detect every genetic alteration, particularly small DNA sequence variants or subtle changes below the resolution of the method used.