Down syndrome is a genetic disorder involving birth defects, intellectual disabilities, characteristic facial features and other health problems such as hearing or visual impairment and heart defects. The specific health problems and severity can vary widely from person to person. Down syndrome is one of the most common genetic birth defects, affecting approximately 1 in every 800 babies.
In most pregnancies, when the baby is conceived, the egg cell from the mother and the sperm cell from the father each contain 23 chromosomes—or half of the number of chromosomes needed to make a complete human cell. When the egg and sperm combine, the resulting embryo contains 46 total chromosomes or 23 pairs; a complete set of genetic material.
Sometimes, however, there may be more than 23 chromosomes present in either the egg or the sperm cell. When an extra chromosome is present during fertilization, this extra chromosome (known as trisomy) becomes part of the embryo’s genetic material and can lead to problems. Having an extra copy of the 21st chromosome results in Down syndrome, also called trisomy 21.
There is currently no reason to believe that prospective parents can do anything to cause or prevent Down syndrome. Doctors and researchers are unable to find a specific cause for the extra chromosome that causes Down syndrome. The only known risk factor is maternal age over 35 at the time of birth. However, more babies with Down syndrome are born to women under age 35 because more women have babies under the age of 35.
The symptoms of Down syndrome include:
- Eyes that slant upward
- Small ears that may fold over slightly at the top
- A small mouth, making the tongue appear large
- A small nose with a flattened nasal bridge
- A short neck
- Small hands with short fingers and a single crease in the palm
- Short stature
- Unusual looseness of the joints
In addition to physical appearance, having an extra 21st chromosome can also cause health problems in different parts of the body, including:
- Congenital heart disease
- Intestinal malformations and/or abdominal wall defects
- Visual impairment such as crossed eyes, nearsightedness, farsightedness or cataracts
- Hearing loss due to fluid in the ear, a nerve defect or a combination of both
- Increased risk for thyroid problems such as hyperthyroidism or hypothyroidism
- Increased risk for leukemia
- Sleep apnea
- Increased risk of colds, bronchitis and pneumonia
Additionally, Down syndrome involves some degree of intellectual disability. The severity of intellectual disability ranges from mild to moderate to severe, with most cases involving moderate intellectual disability.
Not all children with Down syndrome will have all of the physical characteristics or health problems associated with the condition. It is very difficult to determine in advance how severe the physical and intellectual effects of Down syndrome will be, and these effects vary significantly from person to person.
Diagnosis of Down Syndrome
Doctors at Riley at IU Health usually diagnose Down syndrome prenatally through genetic testing such as chorionic villus sampling or amniocentesis. It may also be detected during a fetal ultrasound, although ultrasound is not a 100 percent accurate form of diagnosis because babies with Down syndrome often look the same on ultrasound as babies without Down syndrome.
A physical examination may also reinforce suspicions of Down syndrome after birth, as babies with Down syndrome share unique physical characteristics. If Down syndrome is suspected based on prenatal test results or a physical exam, blood testing will be done after birth to confirm the diagnosis.
The treatments needed for Down syndrome will vary depending on the severity of the condition. While treatment is available for many of the symptoms of and conditions associated with Down syndrome, there is currently no cure for Down syndrome.
As soon as Down syndrome is diagnosed, a multidisciplinary care team will start to work with you on a plan to manage the health problems commonly associated with the condition. When diagnosed prenatally, you may receive genetic counseling to discuss the possible effects of the condition.
Many babies born with Down syndrome have heart defects, and while some may be managed with medicines, others may require surgery. A pediatric cardiologist should examine all babies with Down syndrome and perform an echocardiogram—a special type of ultrasound that examines the structure of the heart—to detect any potential heart defects.
All babies with Down syndrome should receive regular examinations of their eyes and ears so that any problems may be diagnosed and corrected before they cause additional developmental issues. A pediatric ophthalmologist should examine a baby with Down syndrome within the first year of life to identify any vision problems and correct them with glasses or other treatments.
If intestinal malformations and abdominal wall defects are present, these conditions may require surgery to correct them. A dietary specialist may also provide recommendations on how to best feed a baby with Down syndrome, as facial features and intestinal malformations may present unique feeding and nutritional challenges.
Preventive care and vaccinations are especially important for babies and children with Down syndrome due to increased risk for colds, bronchitis, respiratory illnesses and other health problems. You may work with a pediatric pulmonologist to address respiratory health issues. A sleep study may also be necessary to diagnose conditions like sleep apnea which may occur due to large tonsils, large adenoids and/or changes in the respiratory system caused by Down syndrome.
Key Points to Remember
Key Points to Remember
- Down syndrome occurs due to an extra copy of chromosome 21 being present. There is nothing prospective parents can do to cause or prevent Down syndrome.
- Down syndrome is usually diagnosed prenatally.
- Babies and children with Down syndrome have a unique physical appearance and varying degrees of intellectual disability and can have a range of other birth defects and health problems.
- A multidisciplinary care team will work with you from diagnosis throughout your child’s life to manage the health conditions associated with Down syndrome.
Support Services & Resources
Support Services & Resources
There are a variety of resources available for children with Down syndrome and their families. The following websites provide additional information and support:
Riley at IU Health offers a broad range of supportive services to make life better for families who choose us for their children's care.
Down Syndrome Indiana works to enhance the lives of those with Down syndrome by providing support for new parents of a child with Down syndrome as well as information for healthcare professionals and educators.
By educating new and expectant parents, as well as doctors and educators who interact with individuals with Down syndrome, the National Down Syndrome Society works to increase awareness of Down syndrome.
This organization offers information for new and expectant parents, including a preventive care checklist as well as other educational resources related to Down syndrome.
Indiana's First Steps System provides support and guidance to Indiana families who have infants and toddlers with developmental delays or intellectual disabilities.
The American Academy of Pediatrics provides an online guide for families of children with Down syndrome.
In addition to our primary hospital location at the Academic Health Center in Indianapolis, IN, we have convenient locations to better serve our communities throughout the state.
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