One of the most common chromosomal abnormalities, Down syndrome, is a frequent cause of mental retardation and can be diagnosed prenatally. Though Down syndrome occurs in one in 800 births overall, the incidence is much higher with older mothers (one in 106 for mothers over age 40). Though children with Down syndrome have some degree of mental retardation, most can be expected to do many of the same things that any young child can do -- including walking, talking, and being toilet trained -- although generally they learn how to do so later than unaffected children.
Symptoms: A child with Down syndrome generally has characteristic physical features:
- Slanted eyes
- Small ears that fold over at the top
- A small mouth, which makes the tongue appear large
- A small nose with a flattened nasal bridge
- A short neck
- Small hands with short fingers
More than 50 percent of children with this defect have visual or hearing impairments. Ear infections are also common.
Treatment: While Down syndrome is not curable, early intervention allows a child to develop to his full potential. From the baby's birth on, parents and health-care providers need to pay special attention to his development to ensure that he's optimally stimulated. Specialists may also teach parents how to lengthen baby's attention span, for example, or help develop his muscle tone.
Without proper treatment, the recurring ear infections can lead to permanent hearing loss. Between 30 and 50 percent of affected babies also have heart defects, which may require treatment with drugs or surgery. Ten to 12 percent of babies with Down syndrome are born with intestinal malformations that require surgery.