Down syndrome- A Genetic Disorder

Down syndrome (DS or DNS), also known as trisomy 21, is a genetic disorder caused by the presence of all or part of the third copy of chromosome 21.

Down Syndrome Karyotype

It is typically associated with physical growth delays, Characteristic facial features, and mild to moderate disability, low muscle tone, small stature, an upward slant to the eyes, and a single deep crease across the centre of the palm. Although each person with Down Syndrome is a unique individual and may possess these characteristics to different degrees, or not at all. The average IQ of a young adult with Down syndrome is 50, equivalent to the mental ability of an 8 or 9-year-old child, but this can vary widely.


Each person with Down syndrome is an individual — intellectual and developmental problems may be mild, moderate or severe. Some people are healthy while others have significant health problems such as serious heart defects.

Children and adults with Down syndrome have distinct facial features. Though not all people with Down syndrome have the same features, some of the more common features include:

  • Flattened face
  • Small head
  • Short neck
  • Protruding tongue
  • Upward slanting eyelids (palpebral fissures)
  • Unusually shaped or small ears
  • Poor muscle tone
  • Broad, short hands with a single crease in the palm
  • Relatively short fingers and small hands and feet
  • Excessive flexibility
  • Tiny white spots on the coloured part (iris) of the eye called Brush field’s spots
  • Short height

What conditions or disorders are commonly associated with Down syndrome?

children with Down syndrome are at an increased risk for certain health problems. Some of the conditions that occur more often among children with Down syndrome include:

  • Heart defects. Almost one-half of babies with Down syndrome have congenital heart disease (CHD), the most common type of birth defect. CHD can lead to high blood pressure in the lungs, an inability of the heart to effectively and efficiently pump blood, and cyanosis (blue-tinted skin caused by reduced oxygen in the blood.
  • Vision problems. More than half of children with Down syndrome have vision problems, including cataracts (clouding of the eye lens) that may be present at birth. The risk of cataract increases with age. Other eye problems that are more likely in children with Down syndrome are near-sightedness, “crossed” eyes, and rapid, involuntary eye movements.
  • Hearing loss. Up to three-quarters of children with Down syndrome have some hearing loss. Sometimes the hearing loss is related to structural problems with the ear. The AAP recommends that babies with Down syndrome be screened for hearing loss at birth and have regular follow-up hearing exams. Many inherited hearing problems can be corrected. Children with Down syndrome also tend to get a lot of ear infections. These should be treated quickly to prevent possible hearing loss.
  • Hypothyroidism. The thyroid is a gland that makes hormones the body uses to regulate things such as temperature and energy. Hypothyroidism, when the thyroid makes little or no thyroid hormone, occurs more often in children with Down syndrome than in children without Down syndrome. Taking thyroid hormone by mouth, throughout life, can successfully treat the condition. A child may have thyroid problems at birth or may develop them later, so health care providers recommend a thyroid examination at birth, at 6 months, and annually throughout life.
  • Dental problems. Children with Down syndrome may develop teeth more slowly than other children, develop teeth in a different order, develop fewer teeth, or have misaligned teeth compared to children who do not have Down syndrome
  • Blood disorders. Children with Down syndrome are much more likely than other children to develop leukaemia (pronounced loo-KEE-mee-uh), which is cancer of the white blood cells. Children with leukaemia should receive appropriate cancer treatment, which may include chemotherapy. Those with Down syndrome are also more likely to have anaemia (low iron in the blood) and polycythaemia (high red blood cell levels), among other blood disorders. These conditions may require additional treatment and monitoring.
  • Disrupted sleep patterns and sleep disorders. Many children with Down syndrome have disrupted sleep patterns and often have obstructive sleep apnea, which causes significant pauses in breathing during sleep. A child’s health care provider may recommend a sleep study in a special sleep lab to detect problems and determine possible solutions. It might be necessary to remove the tonsils or to use a continuous positive airway pressure device to create airflow during sleep.
  • Epilepsy. Children with Down syndrome are more likely to have epilepsy, a condition characterized by seizures, than those without Down syndrome. The risk for epilepsy increases with age, but seizures usually occur either during the first 2 years of life or after the third decade of life. Almost one-half of people with Down syndrome who are older than age 50 have epilepsy. Seizures can usually be treated and controlled well with medication.
  • Digestive problems. Digestive problems ranging from structural defects in the digestive system or its organs to problems digesting certain types of foods or food ingredients. Treatments for these problems vary based on the specific problem. Some structural defects require surgery. Some people with Down syndrome have to eat a special diet throughout their lifetime.
  • Mental health and emotional problems. Children with Down syndrome may experience behavioural and emotional problems, including anxiety, depression, and Attention Deficit Hyperactivity Disorder. They might also display repetitive movements, aggression, autism, psychosis, or social withdrawal.

What is the treatment for Down syndrome?

Providing support and treatment for a patient with Down syndrome is meant to improve their quality of life.

Infants with Down syndrome may experience developmental delays including time to sit, crawl, walk, and talk so parents need to know that developmental delays are common in children with Down syndrome. Using a team approach to care, physical therapists, occupational therapists, and speech therapists may help improve language, motor, and social skills to the maximum achievable by the individual person.

Risk factors

Some parents have a greater risk of having a baby with Down syndrome. Risk factors include:

  • Advancing maternal age.A woman’s chances of giving birth to a child with Down syndrome increase with age because older eggs have a greater risk of improper chromosome division. A woman’s risk of conceiving a child with Down syndrome increases after 35 years of age. However, most children with Down syndrome are born to women under age 35 because younger women have far more babies.
  • Being carriers of the genetic translocation for Down syndrome. Both men and women can pass the genetic translocation for Down syndrome on to their children.
  • Having had one child with Down syndrome. Parents who have one child with Down syndrome and parents who have a translocation themselves are at an increased risk of having another child with Down syndrome. A genetic counsellor can help parents assess the risk of having a second child with Down syndrome.


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