Mosaic Down syndrome

Mosaic Down syndrome is a genetic condition that occurs when a person has an extra copy of chromosome 21 in some of their cells, but not all. This mosaic pattern can result in a milder form of Down syndrome, as the presence of normally developed cells can balance out some of the effects. Individuals with mosaic Down syndrome may exhibit various characteristics associated with Down syndrome, such as developmental delays and distinct physical features, but the severity and range of symptoms can vary widely. Diagnosis typically happens through genetic testing.