Chromosome 21 is the smallest human chromosome, and procedures for examining human chromosomes were still being developed during the first part of the century. Many early cytologists had ...

Down Syndrome is also known as Trisomy 21, and Burger wants to raise awareness and contribute to research on the genetic condition.

The new Rangers first baseman announced Friday that he will wear No. 21 to pay tribute to Penelope, who was born with Down ...

Most people have two copies of each chromosome, for a total of 46. People with Down syndrome have 3 copies of the 21st chromosome, making a total of 47. Down syndrome is also called Trisomy 21.

The date was chosen keeping in mind the 21st chromosome that is responsible for causing Down Syndrome. Since then, the ...

ARLINGTON, Texas - New Texas Rangers corner infielder Jake Burger picked his new jersey number to honor his daughter. Burger ...

Photograph of a karyotype - the collection of chromosomes within each cell of an organism - from a male mouse engineered by Johns Hopkins Medicine researchers to model Down syndrome in a human.

According to the CDC, here is why No. 21 is significant in this case: Down syndrome is a condition in which a person has an extra copy of chromosome 21. Chromosomes are small "packages" of genes ...