What is Down syndrome?
Down syndrome is a common congenital condition affecting about one in every 700 babies in Canada. Congenital means the condition is present at birth. Down syndrome is due to a genetic variation and is not related to race, nationality, religion or socio-economic status.
What causes Down syndrome?
Down syndrome is a genetic condition caused by having “extra” genetic material (or too many genes), of chromosome 21.
Trisomy 21
Each cell typically has 23 pairs of chromosomes for a total of 46 chromosomes. In children with Down syndrome, each cell in the body has 47 chromosomes because there is a third copy of chromosome 21. This is called trisomy 21 and affects approximately 94% of people with Down syndrome. This is most often a random genetic event and not caused by anything that either parent has done.
Other causes of Down syndrome
In a small number of Down syndrome cases, the extra chromosome 21 is the result of an unbalanced translocation. With translocation Down syndrome, the extra chromosome is attached or "trans-located" to a different chromosome rather than being a separate chromosome 21. There are still three copies of chromosome 21 with this type of Down syndrome, which occurs about 2-3% of the time. Translocation Down syndrome can be inherited from an unaffected parent.
See Translocation Down Syndrome for more information.
Another type of Down syndrome is called mosaicism. It affects about 2-3% of patients with Down syndrome. In this situation only some of the cells in the body have an extra copy of chromosome 21.
See Mosaic Down Syndrome: What You Need to Know for more information.
What are the chances of having a baby with Down syndrome?
Women older than 35 years of age are at a greater risk to give birth to a child with Down syndrome, in comparison to women younger than 35 years of age. This risk increases with the mother’s age. However, because most babies in general are born to women who are younger than 35 years of age, most babies with Down syndrome (80%) are born to women younger than 35 years of age.
The risk is also greater for parents who already have a child with Down syndrome, or for mothers or fathers who have a balanced translocation.
If you think you may be at risk, talk to your health-care provider.
Diagnosis of Down syndrome
Most babies born with Down syndrome are diagnosed with the condition after birth. However, there are several ways to test for Down syndrome before a baby is born. These include various blood tests along with an early fetal ultrasound to determine the chances that a baby might have Down syndrome.
These tests are sometimes referred to as integrated prenatal screening or first trimester screening. In recent years, non-invasive prenatal testing has been used. This is a very accurate blood test that helps determine if a fetus will have Down syndrome.
Other types of tests used to detect Down syndrome in a fetus include chronic villus sampling and amniocentesis.
Although these tests may detect Down syndrome before a baby is born, they are not able to predict how affected the child will be with regards to their development or medical issues.
Expectant parents should speak to their health-care providers for more information on diagnostic tests and procedures. A genetics counsellor can also provide more information, either prenatally or after delivery.
Treatment of Down syndrome
There is no cure for Down syndrome. However, there are many supportive treatments available to help target the associated medical and developmental challenges. Because children with Down syndrome can be affected differently, there are no standard medications prescribed for all children with Down syndrome.
Medical problems for a child with Down syndrome often change with age. Your child’s health-care provider should be aware of these age-specific medical problems and organize the appropriate testing according to your child’s age. Health supervision guidelines for families are available online from the American Association of Pediatrics (AAP).
These guidelines highlight the common medical and developmental issues that should be monitored on a regular basis as well as the recommended tests that should be done on a yearly basis.
The full AAP guidelines for professionals are also available.
Children with Down syndrome benefit from loving homes, early intervention, inclusive and accommodating education, appropriate medical care and positive public attitudes. An example of a typical program for a child with Down syndrome would include:
- Early intervention services
- Physiotherapy for gross motor skills
- Occupational therapy for feeding, general development and fine motor skills
- Speech and language therapy to work on communication skills
- Collaboration between your child’s health-care professionals and daycares, schools, and other extra-curricular programs, to optimize your child’s care.
How does Down syndrome affect the body?
Babies with Down syndrome are more likely to be born prematurely. Their birth weight and length may be below average. Babies with Down syndrome are also more likely to have low muscle tone leading to floppiness (hypotonia).
In addition, there are several physical features that—when taken all together—are more often seen in children with Down syndrome. These features include upward slanting eyes, flattened bridge of the nose, prominent tongue and low set ears. Although children with Down syndrome share some common physical characteristics, they do not all look the same. A child with Down syndrome will look more like their parents, or other family members, than other children with the syndrome.
Children with Down syndrome also vary in personality and ability just like other children. They will all have intellectual impairment, delayed motor development, and speech problems. However, the level of impairment will be different for each individual. A child with Down syndrome may learn new skills slower than a child without Down syndrome. However, most children with Down syndrome should still be able to learn the same skills as other children, including walking, talking and being toilet trained. And, just like a child who does not have Down syndrome, they will have their own personalities, sense of humor, favourite things, music they love and people they like to be around.
There are several medical conditions that can affect children with Down syndrome. The most common medical conditions are hearing (75%) and vision problems (60%). About 40-50% of children with Down syndrome have congenital heart disease. A smaller number of children (8-12%) have problems with their gastrointestinal tract at birth.
Children with Down syndrome are more likely to have certain infections, respiratory, blood and dental problems as well as thyroid and other medical conditions.
The effects of these conditions vary from child to child. They may be more serious in some children than in others. Some children with Down syndrome may have none of these medical conditions, while others will have several. With proper medical care most children and adults with Down syndrome can lead healthy lives.
While Down syndrome is associated with medical and developmental challenges, the condition varies widely from one child to another. Down syndrome is a spectrum, which means that some children may have many medical problems and others may have few. In the same way, some children will experience more cognitive and developmental challenges and others will have few. Regardless of the degree of medical or developmental problems, all children with trisomy 21 will likely experience some medical problems throughout their lives and will have some degree of cognitive impairment called intellectual and developmental disability (IDD). Each person with Down syndrome has different talents and the ability to thrive.
Children with Down syndrome attend school and participate in recreational activities just like other children. They may need additional supports or accommodations during these activities, and these should be discussed with the specific program. Many adults with Down syndrome hold jobs, live independently and contribute to their family, friends and community in many different and meaningful ways.
The average life expectancy of individuals with Down syndrome is 60 years. Many people with Down syndrome will live into their sixties and seventies. In addition to some of the conditions mentioned above, adults with Down syndrome are more likely to have Alzheimer’s disease. Alzheimer's is a neurologic disease that causes problems with memory, thinking and behaviour.
For more information, see Down syndrome: Related medical conditions.
If you have any questions or concerns about any of these conditions, speak with your child’s health-care provider.
When to see a health-care provider
Babies and children with Down syndrome should be followed by a health-care provider. Your child’s health-care provider will care for them during illness and will see your child for annual health check-ups.
Some cities have multi-disciplinary clinics that offer expertise and help co-ordinate care for children with Down syndrome. Check with your regional children’s hospital to find out if these programs are available in your area.
Resources
Patient Resources from the Down Syndrome Program at MGfC and Mass General
People with Down syndrome who are achieving great things
Ruby’s Rainbow Rockin’ Recipients – students with Down syndrome who have received scholarships to pursue higher education
Chris Nikic – the first person with Down syndrome to complete in an Iron Man Competition
Collette Divitto (Collette’s Cookies) – Bakery owner, entrepreneur and motivational speaker with Down syndrome
Olly Sardelic – 5-year-old artist with Down syndrome, whose art is exhibited at Queen St W art gallery
Madison Tevlin – Canadian actor who works on Entertainment Tonight and CBC’s show “Who Do You Think I Am”
Rachel Handlin – an artist and the first person with Down syndrome to receive a Master of Fine Arts