Down Syndrome Causes and Symptoms

What is Down syndrome?

Down syndrome is a genetic disorder in which, most often, a third copy of chromosome 21 is present in cells because of an abnormal cell division when the egg and sperm first meet. As such, it is not truly a disease or illness that is curable or preventable but rather a lifelong challenge for patient and family to maximize quality of life.

The syndrome is characterized by short stature, a typical flat, broad facial structure, and intellectual disability. Importantly, the extra chromosome material may affect many of the body's organ systems, and congenital heart abnormalities and failure of the gastrointestinal tract to develop properly may require emergent surgery in the first months of life. Screening is often performed for other physical abnormalities like congenital eye cataracts, ear disease, thyroid disorders, and instability of the cervical spine.

What are the characteristic developmental delays in Down syndrome?

The goal for a child with Down syndrome is to live a long, healthy, and productive life. In the early years there can be significant developmental delays in crawling, walking, and speech. This may affect emotional and social growth as well. A team effort involving health care professional and parent is often joined by physical, occupational, and speech therapists to offer opportunities for improvement.

The intellectual capabilities of an individual with Down syndrome vary widely, and the ability may be present to function well in high school and beyond. Independent living and employment are goals to increase the quality of life of the patient. While about 25% of infants with Down syndrome die in their first year of life, average life expectancy has increased to 50 years of age. Unfortunately, Alzheimer's dementia may develop after age 40.

Who is at risk for having a baby with Down syndrome?

While mothers who are older have a higher risk of having a child with Down syndrome, the risk is present for women of all ages. Raising the affected child is a lifelong commitment and comes with its own set of emotions from fear and frustration to anger and guilt. In addition to the health care team, there are many support groups available to help families cope with the issues that accompany the challenge and rewards. The goal remains to raise a healthy, productive child who enters mainstream society, succeeds in school and the workplace, and lives either with family or independently.

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Medically reviewed by Margaret Walsh, MD; American Board of Pediatrics


"Birth Defects." Centers for Disease Control and Prevention. 15 July 2013.

"Calculation of the risk of Down's syndrome." Wolfson Institute of Preventive Medicine.