|Description:||This illustration, courtesy of the National Human Genome Research Institute, depicts the karyotype that would represent the chromosomal configuration seen in a person with Down syndrome.|
A karyotype represents a complete set of chromosomes in each and every eukaryote cell of an individual organism. The chromosomes are arranged in pairs, and aligned using the position of each chromosome’s centromere. Pairs are then arranged into groups “A” through “G”, based on size. In this particular case, the cells in a person with Down syndrome contain an extra chromosome 21 (arrow), and is therefore, known as “trisomy” 21.