Down syndrome is a common congenital condition affecting about one in every 700 babies in Canada. Children with Down syndrome have extra genetic material from chromosome 21, most often a third copy of chromosome 21. While Down syndrome is associated with medical and developmental challenges, each child is affected differently. The medical and developmental issues may be more serious in some children than in others.
There are several medical conditions that can affect children with Down syndrome.
Heart
About 40–50% of children with Down syndrome have a congenital heart defect. Congenital means they were born with the condition or defect. Many of these defects can be corrected through surgery.
Children with Down syndrome are routinely screened for congenital heart defects. Sometimes a congenital heart defect can be detected before a baby is born. Atrioventricular septal defects (AVSDs) are the most common type of heart defect in children with Down syndrome. AVSD is caused by a failure of the heart’s four chambers to form properly. Other types of congenial heart conditions such as atrial septal defects, ventricular septal defects, patent ductus arteriosus and tetralogy of Fallot are also common.
These conditions may be detected and diagnosed by an experienced health-care provider listening for a heart murmur or if the baby has low oxygen levels. However, it is possible to have a major heart problem without hearing a murmur or having low oxygen levels. It is very important for every baby with Down syndrome to have an echocardiogram (heart ultrasound) even if the prenatal ultrasounds were normal.
Certain kinds of congenital heart defects need to be repaired by surgery early in a baby’s life, while other types of congenital heart disease can be observed closely by a cardiologist. A paediatric cardiologist is a specialist who can diagnose and treat children with congenital heart disease. Speak to your child’s cardiologist for more details about the care plan for your child’s heart condition.
Gastrointestinal tract
A smaller number of children are born with gastrointestinal tract abnormalities. The gastrointestinal tract includes the esophagus, stomach and intestines. Surgery can correct many of these gastrointestinal congenital abnormalities.
Some of the common gastrointestinal and digestive problems that affect children with Down syndrome are listed below.
Gastrointestinal narrowing
If a newborn with Down syndrome has severe vomiting from birth, they may be among the approximately 12% of babies with Down syndrome who have a gastrointestinal narrowing (atresia). Most commonly, the first part of the small intestine—the duodenum—is blocked. The end result is that digested food cannot pass through the duodenum. The treatment for this is surgical removal of the blockage.
Hirschsprung disease
Hirschsprung disease affects fewer than 1% of infants with Down syndrome. Hirschsprung disease occurs when the last part of the large intestine does not function properly due to a lack of nerve cells. As a result, affected individuals have severe constipation. When this is severe, it may cause a bowel obstruction. The treatment involves surgically removing the portion of colon that does not function properly.
Constipation
People with Down syndrome can be constipated for all of the same reasons that people without Down syndrome become constipated, such as poor diet and lack of exercise. However, people with Down syndrome are also prone to conditions that can result in constipation, including hypothyroidism, Hirschsprung disease, and celiac disease. If constipation is not related to these conditions, caregivers and physicians should work together to explore safe laxative medications.
Hearing loss
In children, hearing loss can affect educational, language-related, and emotional development. Monitoring and treatment of the ears and ear diseases can lessen the incidence of hearing loss. The American Academy of Pediatrics (AAP) recommends audiologic testing at birth, then again between six and 12 months of age, followed by yearly hearing tests. Hearing aids should be considered even in cases of mild hearing loss to prevent delays in educational, emotional and language-related development.
Visual impairment
The greatest concern for children with Down syndrome is congenital cataracts (lack of clearness to the lens of the eye). If cataracts are present and left untreated, this condition can lead to blindness. Cataracts may not be visible to the naked eye. The proper way to test for cataracts is to have an experienced health care provider examine the eyes using an ophthalmoscope. Congenital cataracts usually need to be surgically repaired immediately. If caught early, vision can be restored and blindness can be avoided. Ophthalmologists are the eye doctors and surgeons who treat cataracts and similar eye conditions.
Refractive error (the need for glasses) is much more common in children with Down syndrome than in the general population. Strabismus (eye misalignment), also known as lazy eye, is also more common. It is important to diagnose strabismus as a child, as this condition can result in amblyopia, which is a loss of vision or stereopsis which is a loss of depth perception.
In addition to the need for eyeglasses, many children with Down syndrome have tear duct abnormalities, which caregivers will notice as frequent discharge and tearing from the eyes, worsened by colds. This should be monitored by an eye doctor if is it not improving, as sometimes this condition may need to be surgically corrected.
Thyroid dysfunction
Hypothyroidism is the most common endocrine problem in children with Down syndrome. It is estimated that approximately 10% of children with Down syndrome have congenital or acquired thyroid disease. Thyroid hormone is important for growth and cognitive (brain) development throughout childhood. Abnormal thyroid levels can be detected through routine blood tests.
Increased likelihood of certain infections
Individuals with Down syndrome may have a high frequency of infections, usually of the upper respiratory tract. The infections are characterized by increased severity and prolonged course of disease, which are partially related to differences in their immune system. Non-immunological factors, including abnormal anatomical structures (e.g. small ear canal, narrow trachea) and gastro-esophageal reflux, may also play a role in the increased frequency of respiratory tract infections.
Cervical spine instability or dislocation
Up to 25% of children with Down syndrome may have atlantoaxial instability (AAI). This is a developmental abnormality of their spinal column that causes increased flexibility between the first and second bones of the cervical spine (neck). Most of the time this does not cause any symptoms or problems. It is important to be aware of the potential for problems, however, because dislocation of the vertebrae that protect the spinal cord may lead to spinal cord injury. Routine neck X-rays are no longer recommended by the AAP. Symptoms that are associated with AAI include a change in the way the individual walks, difficulty using their arms or hands, changes in bowel or bladder function, weakness, or if there is new onset neck pain or head tilt. You should contact your doctor immediately if any of these concerns are present.
Seizures
Seizures are caused by abnormal brain activity that lead to abnormal body movements. Children with DS are five times more likely than the general population to have seizures. This may occur in infancy or later in life. It is important to detect and treat seizures early to ensure the best brain and cognitive development.
Blood disorders
Individuals with Down syndrome occasionally have abnormalities in their blood cells. This is why it is recommended that they have a complete blood count done at birth, followed by annual testing. In many instances, the abnormalities resolve spontaneously over a period of time, and this is especially common among newborn babies with Down syndrome. Rarely, if the condition persists, this may lead to a type of cancer called leukemia. Leukemia is a treatable blood cancer that needs to be cared for by a blood specialist called an oncologist.
If you have questions or concerns about any of these conditions, speak with your child’s doctor.