Down syndrome is a genetic disorder caused by the presence of an extra chromosome 21. It is the most common chromosomal anomaly, occurring in about 1 in 800 to 1000 live births. People with Down syndrome often experience cognitive delays, characteristic facial features, and health issues such as congenital heart defects and thyroid problems. Treatment focuses on medical care, physical therapy, occupational therapy, and speech therapy to help patients develop skills and manage health conditions. Life expectancy has increased to 50-55 years with proper support and treatment.