All About Down Syndrome

What is Down syndrome?

Down syndrome is a genetic condition resulting from an additional chromosome in the child’s cells. Each cell contains three copies of chromosome 21, instead of the usual two, a condition also referred to as Trisomy 21.

Individuals with Down syndrome are born with distinct physical features and may experience various associated medical issues.

What are the causes and risk factors of Down syndrome?

Causes

Nondisjunction: Trisomy 21 is the most common cause, accounting for about 95% of cases. It occurs when there is an error in cell division (nondisjunction), resulting in an embryo with three copies of chromosome 21 instead of the usual two.
Mosaicism: This rare form, occurring in about 1-2% of cases, results from a mixture of two types of cells, some with the normal 46 chromosomes and others with 47 chromosomes due to the extra chromosome 21.
Translocation: This occurs when part of chromosome 21 becomes attached (translocated) to another chromosome, before or at conception. Children with this form of Down syndrome have two copies of chromosome 21, but they also have additional material from chromosome 21 attached to another chromosome. This form accounts for about 3-4% of cases.

Risk Factors

Advanced maternal age: The risk of having a child with Down syndrome increases with the mother’s age. Women aged 35 and older are at a higher risk, with the likelihood increasing significantly after age 40.
Previous child with Down syndrome: Parents who have one child with Down syndrome or who have a translocation involving chromosome 21 are at a higher risk of having another child with the condition.
Parental carrier of genetic translocation: Either parent may be a carrier of a balanced translocation, which can increase the risk of having a child with Down syndrome.
Family history: While most cases of Down syndrome are not inherited, having a family history can slightly increase the risk.

What are the characteristics of individuals with Down syndrome?

Here are some of the notable characteristics of individuals with Down syndrome:

1. Physical features

These are some of the physical features that you may notice in individuals with Down syndrome:

A face with a flatter appearance, particularly noticeable along the bridge of the nose
Almond-shaped eyes that slant upwards
Short neck
Small ears
Protruding tongue
The iris of the eye having white spots on it
Small hands and feet
Palm with single line across it (palmar crease)
Small pinky fingers that occasionally curve toward the thumb
Poor muscle tone or loose joints
Shorter height compared to children and adults of similar age

2. Cognitive and behavioural symptoms

Cognitive impairment, or having difficulties thinking and learning, is a normal condition in people with Down syndrome and typically ranges from mild to moderate. Severe cognitive impairment associated with Down syndrome is rare.

You may notice some common cognitive and behavioural problems that include:

Short attention span
Poor judgement
Impulsive behaviour
Slow learning
Delayed language and speech development

While it may take longer for most children with Down syndrome to develop communication skills compared to other children, they can still acquire the necessary communication skills. Initiating and sustaining early speech and language interventions to promote expressive language and improve speech can help with this.

How is Down syndrome diagnosed?

Down syndrome is diagnosed via these two methods, prenatally and at birth:

Before birth

There are two types of tests for Down syndrome that can be conducted before a baby is born: prenatal screening tests and diagnostic tests.

Prenatal screening tests can estimate the likelihood of the foetus having Down syndrome, offering a probability rather than telling you whether your foetus has Down syndrome or not.
Diagnostic tests such as chorionic villus sampling (CVS) and amniocentesis, on the other hand, can provide a conclusive diagnosis with almost 100% accuracy. However, these tests are at risk of causing a spontaneous termination (miscarriage).

At birth

Down syndrome is typically recognised at birth through the observation of specific physical characteristics, some of which are mentioned above. However, since these characteristics may also be present in babies without Down syndrome, a chromosomal analysis called a karyotype is conducted to confirm the diagnosis.

A faster method is the Fluorescence in situ hybridisation (FISH), another genetic test that can help confirm a diagnosis by visualising and mapping the genetic material in an individual’s cells.

What are the health complications associated with Down syndrome?

Adding on to intellectual and developmental disabilities, children with Down syndrome also face a higher risk for specific health problems. However, it is important to note that each individual with Down syndrome is unique, and not everyone will experience severe health problems. Many of these associated conditions can be addressed through medication, surgery, or other means.

Heart defects

Nearly one-half of babies with Down syndrome have congenital heart disease (CHD), which is the most prevalent type of birth defect. CHD can cause high blood pressure in the lungs, in which the heart is unable to pump blood effectively and efficiently, and cyanosis (bluish-tinted skin due to reduced oxygen in the blood).

Gastrointestinal defects

Gastrointestinal defects, or digestive problems, can vary from structural issues in the digestive system or its organs to difficulties in digesting specific types of food or ingredients. Some individuals with Down syndrome may need to adhere to a special diet throughout their entire lives.

Immune disorders

Individuals with Down syndrome face an elevated risk of death due to untreated and unmonitored infections compared to most people. Down syndrome frequently challenges the immune system which can lower the body’s ability to fight off infections, so even what seems to be minor infections should be treated and monitored immediately and continuously.

Sleep apnoea

Many children with Down syndrome experience disrupted sleep patterns, and they usually have obstructive sleep apnoea, which leads to significant pauses in breathing during sleep.

Spinal problems

Certain children with Down syndrome have misshapen bones in the upper part of the spine, situated beneath the base of the skull. These misshapen bones can exert pressure on the spinal cord and heighten the risk of injury.

Obesity

Youth with Down syndrome exhibit a higher prevalence of being overweight and obese in comparison to the general youth population. Weight management recommendations tailored for the general population may be unsuitable for youths with Down syndrome because of physiological and cognitive differences seen in this group of individuals.

Dementia

Individuals with Down syndrome face a heightened likelihood in experiencing serious heart-related issues, which puts them at increased risk for early onset dementia.

Leukaemia

Children with Down syndrome face an increased risk of developing leukaemia compared to other children, which is cancer of the white blood cells. Children with leukaemia should receive appropriate cancer treatment, which may often include chemotherapy.

Does Down syndrome need to be treated?

Down syndrome is a lifelong condition, any relevant treatments will be of great help in improving the physical and intellectual abilities of individuals with Down syndrome.

Some of the rehabilitation activities are listed below for your reference:

Physical therapy involves engaging in activities and exercises designed to enhance motor skills, boost muscle strength, and improve posture and balance.
Speech-language therapy is beneficial for children with Down syndrome as it helps improve their communication skills and enhances the effective use of language.
Occupational therapy helps identify ways to adapt to everyday tasks and environments to match an individual’s needs and capabilities.
Emotional and behavioural therapies aim to identify constructive responses to both desirable and undesirable behaviours.

Can Down syndrome be prevented?

Currently, there is no known way to prevent Down syndrome. However, certain measures can help prospective parents understand their risk and make informed decisions such as genetic counselling, prenatal screening and diagnostic tests, and understanding the risk factors.

Make an appointment at Pantai Hospitals

Consult our doctors if your child has Down syndrome or if you are seeking a prenatal diagnosis for this condition. A dedicated and expert team of General Paediatricians at Pantai Hospitals is available for consultation to provide the best care and assistance.

Get in touch with us to book an appointment today if you have questions regarding Down syndrome. We assure you the best possible care tailored to your specific needs.

Pantai Hospital has been accredited by the Malaysian Society for Quality in Health (MSQH) for its commitment to patient safety and service quality.