Down syndrome results from an extra copy of the 21st chromosome. The three types of Down syndrome can result in different levels of symptom severity. Down syndrome (sometimes called Down’s ...

The most common type of Down syndrome is trisomy 21, which accounts for 95% of all cases. (iStock) One risk factor associated with Down syndrome is the age of the mother — for a 25-year-old ...

“In the most common type of Down syndrome, there are 47 chromosomes, with the extra one being chromosome 21 — so the patient has three No. 21 chromosomes in all the cells of their body.

There are three types of Down syndrome. Trisomy 21: Approximately 95% of people with Down syndrome have Trisomy 21, which occurs, according to the Cleveland Clinic, ...

Down syndrome is a congenital (present at birth) genetic condition that occurs when a person has three copies of chromosome ...

A mother shares her story about being diagnosed with mosaic Down syndrome. A mom of 3 learned she had mosaic Down syndrome through genetic testing. Here's why she's 'happy' with the diagnosis.