A common condition among the mentally retarded, it occurs in approximately 1 out of 600 live births. People with Down’s syndrome exhibit many similar characteristics, but also have unique features and personalities.

Two common clinical features are the present of the epicanthus fold on the inner corner of the eye and a curved little finger. The cause of Down’s syndrome is the presence of an extra chromosome in the 21st pair (see Poster #X). In most instances, the excess chromosome is thought to be present in the egg cells before conception. The problem occurs more often in older mothers. The risk of recurrence in subsequent pregnancies is quite low, but genetic counseling and amniocentesis or chorine biopsies are recommended.