Down syndrome occurs when a person is born with extra genetic material from chromosome 21. Usually, this is due to an extra chromosome. Chromosomes are groups of genes, the material that tells the body how to grow, develop, and function.
People typically have 46 chromosomes when they are born. Most often, people with Down syndrome have an extra copy of chromosome 21, for a total of 47 chromosomes.
Down syndrome affects the development of the brain and body. People with Down syndrome have a wide range of abilities and disabilities. There are several medical and mental health conditions that occur at higher rates in people with Down syndrome.
Doctors categorize Down syndrome into three categories. They include:
Down syndrome is the most common chromosome-related condition in the United States. Roughly 6,000 babies are born with the condition in the U.S. every year (about 1 in every 700 babies). More than 300,000 people are living with the condition in the U.S. today. The chance of giving birth to a child with Down syndrome increases as women grow older.
Each human cell typically contains 23 pairs of chromosomes. Down syndrome occurs because of changes in the way cells in chromosome 21 divide. Every person with Down syndrome has an extra amount of this chromosome in some or all of their cells.
Down syndrome is a genetic condition. In the most common type of Down syndrome, the condition occurs sporadically and is not inherited. However, when translocation or mosaicism is the cause of Down syndrome, hereditary (passed down among family members) should be looked at as a cause.
Different people with Down syndrome have variable symptoms. The condition causes physical, cognitive and behavioral symptoms.
Physical signs of Down syndrome can include:
Common learning and behavioral symptoms of Down syndrome include:
Doctors can diagnose Down syndrome before a baby is born or at birth. People may choose to participate in counseling or join a support group if they find out the baby they are carrying has Down syndrome.
In prenatal (before birth) tests called screenings, a doctor may use blood tests and ultrasound (imaging test) to look for “markers” that suggest Down syndrome may be present.
In these tests, a doctor removes a sample of cells from the part of the womb called the placenta (CVS), or the fluid surrounding the baby (amniocentesis), to look for abnormal chromosomes. Parents can choose whether or not to have these prenatal screenings.
At birth, doctors perform a physical exam to look for the physical signs of Down syndrome. To confirm the diagnosis, doctors use a blood test called a karyotype. In this test, the doctor takes a small sample of blood and studies it under a microscope to see if an extra amount of chromosome 21 is present.
Treatment for Down syndrome varies by individual. These treatments typically start in early childhood and aim to help people live productive and fulfilling lives.
Your physician will help you develop an appropriate care team for a patient with Down syndrome. The care team may include:
People with Down syndrome often have associated medical conditions that are either present at birth or develop over time. Doctors can help manage these conditions with medications or other care. Common conditions of Down syndrome can include:
Down syndrome can’t be prevented, but parents can take steps that may reduce the risk. The older the mother, the higher the risk of having a baby with Down syndrome. Women can reduce the risk of Down syndrome by giving birth before age 35.
Many traits and conditions in people with Down syndrome are manageable with treatment and therapies. Medical care, support and education enable people with Down syndrome to live happy, active lives. Many people with Down syndrome live to age 60 or older.
Many resources are available to people with Down syndrome and their families. Parents of children with Down syndrome may need support with the special needs of their infants and toddlers. Many families join Down syndrome support groups to share experiences and ways to help their loved one live a healthy and fulfilling life.
People with Down syndrome will likely need assistance throughout their lives. In addition to ongoing therapies, this could include help with education, employment and living independently. A variety of organizations offer resources to help educate and empower people living with Down syndrome and their families. The National Down Syndrome Society and the National Association for Down Syndrome are two of the most common resources people use for more information and support. Locally, in northeast Ohio, The Up Side of Downs provides support, education and advocacy for individuals with Down syndrome, their families and communities (see References section).
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or healthcare provider. Please consult your healthcare provider for advice about a specific medical condition. This document was last reviewed on: 06/13/2018