label: Down syndrome
label_lc: down syndrome
description: Down syndrome is a chromosomal abnormality caused by the presence of a third (partial or total) copy of the chromosome 21 genetic material and that is characterized by variable intellectual disability, muscular hypotonia, and joint laxity, often associated with a characteristic facial dysmorphism and various anomalies such as cardiac, gastrointestinal, or endocrine defects.