A karyotype is an organized profile of a person's chromosomes. Two chromosomes specify sex, XX for female and XY for male. The rest are arranged in pairs, numbered 1 through 22, from largest to smallest. This arrangement helps scientists quickly identify chromosomal alterations that may result in a genetic disorder.

To make a karyotype, scientists take a picture of the chromosome from one cell, cut them out, and arrange them using size, banding pattern, and centromere position as guides.