In most cases, Down syndrome is caused by an extra chromosome 21. Downs children have a widely recognized characteristic appearance. Retardation of normal growth and development is typical and most affected children never reach average adult height. The average mental age achieved is 8 years old. Congenital heart defects are frequently present in these infants.
Early mortality is often a result of cardiac abnormalities.
Obstruction of the gastrointestinal tract may require major surgery shortly after birth. Characteristic abnormalities are revealed by a physical examination . There is no specific treatment for Down syndrome. Special education and training is offered in most communities for mentally handicapped children. Specific heart defects may require surgical correction.