Trisomy 18, also known as Edwards syndrome, is a genetic condition caused by the presence of an extra 18th chromosome. This abnormality leads to severe developmental delays and various physical abnormalities. Common features include a small head, clenched fists, and heart defects. Most affected infants have a short life expectancy, with many not surviving past their first year. Diagnosis of Trisomy 18 can be made through prenatal testing, such as amniocentesis or chorionic villus sampling. While there is no cure, supportive care can help manage symptoms. Early intervention and specialized care may improve quality of life for those who survive longer.