Down syndrome is a chromosomal abnormality that changes the course of development and causes a set of mental and physical characteristics related to having an extra copy of Chromosome 21. According to the Centers for Disease Control and Prevention, approximately 6,000 babies are born in the United States each year with Down syndrome, or approximately 1 out of every 691 live births. Down syndrome is the most frequent chromosomal cause of mild to moderate intellectual disability, and it occurs in all ethnic and economic groups. Currently, more than 400,000 people are living with Down syndrome in the United States, according to the National Down Syndrome Society.
Your risk of having a baby with Down syndrome is higher if:
- You are older when you get pregnant. Many doctors believe that the risk increases for women age 35 and older.
- You have a brother or sister who has Down syndrome
- You had another baby with Down syndrome
- There are two types of tests for Down syndrome during pregnancy:
- A prenatal screening test. This test can show an increased likelihood that a fetus has Down syndrome, but it cannot determine Down syndrome is definitely present. If a screening test shows an increased likelihood, a diagnostic test can be ordered.
- A prenatal diagnostic test. This test can determine with certainty that Down syndrome is present. Diagnostic tests carry a slightly greater risk to the fetus than do screening tests.
In other cases, the baby is diagnosed after birth. A doctor may have a good idea that a baby has Down syndrome based on the way the baby looks and the result of a physical exam, and a blood test will be done for confirmation. People with the syndrome also are more likely to be born with heart abnormalities, and they are at increased risk for developing hearing and vision problems, Alzheimer disease, and other conditions.
Having extra or abnormal chromosomes changes the way the brain and body develops. Most children with Down syndrome have distinctive facial features, such as a flat face, small ears, slanting eyes, small mouth, short neck, short arms and legs, low muscle tone and loose joints. They also have some degree of intellectual disability; however, this varies from person to person and is usually mild to moderate. Generally, children with Down syndrome reach key developmental milestones later than other children. Physical development in children with Down syndrome is often slower than development of children without Down syndrome. For example, because of poor muscle tone, a child with Down syndrome may be slow to learn to turn over, sit, stand, and walk. Despite these delays, children with Down syndrome can learn to participate in physical exercise activities like other children. It may take children with Down syndrome longer than other children to reach developmental milestones, but they will eventually meet many of these milestones.
Children with Down syndrome show specific delays in learning to use spoken language relative to their non-verbal understanding. Almost every child will have expressive language that is delayed relative to their language comprehension. The children experience two types of expressive difficulty – delay in mastering sentence structures and grammar, and specific difficulties in developing clear speech production. Motor skills develop at a slower rate for children with Down syndrome than for those without. These delays in motor development reduce infants’ opportunities for exploring and learning about the world around them and therefore further affect cognitive development.
Other common cognitive and behavioral problems may include:
- Short attention span
- Poor judgment
- Impulsive behavior
- Slow learning
- Delayed language and speech development
There is no single, standard treatment for Down syndrome. Treatments are based on each individual’s physical and intellectual needs as well as his or her personal strengths and limitations. People with Down syndrome can receive proper care while living at home and in the community. A child with Down syndrome likely will receive care from a team of health professionals, including, but not limited to, physicians, special educators, speech therapists, occupational therapists, physical therapists, and social workers.
Although Down syndrome is a lifelong disability, it can be treated through a variety of appropriate educational and behavioral interventions in addition to occupational therapies, speech and language interventions, behavior modification, and parent training. With appropriate intervention, care and support, most children with Down syndrome can grow up healthy, happy and live active, productive lives into adulthood. In recent decades, life expectancy for people with Down syndrome has increased dramatically, from 25 years in 1983 to 60 years’ today.