The cause of Down syndrome: the most common cause of Down syndrome is when a sperm cell or egg cell has an extra copy of chromosome 21 so the person who is born has one extra chromosome.
Signs and symptoms: Down syndrome causes a distinct facial appearance in the person effected. Down syndrome also causes an intellectual disability, and it is also sometimes associated with heart disease.
More than 400,000 people are living with Down syndrome in the United States.
One celebrity with Down syndrome is Lauren potter. Lauren potter is in the show glee