Understanding Down Syndrome

Overview of Down Syndrome

Down syndrome is a genetic condition characterised by the presence of an extra chromosome in a child’s cells. Specifically, individuals with Down syndrome have three copies of chromosome 21, a condition known as Trisomy 21. This additional genetic material affects the development of the body and brain, leading to distinct physical features and an increased risk of various medical conditions.

Causes of Down Syndrome

• Trisomy 21 (Nondisjunction): The most common cause of Down syndrome, responsible for approximately 95% of cases, occurs due to an error in cell division, leading to three copies of chromosome 21.
• Mosaicism: This rare form, seen in about 1-2% of cases, involves a mix of cells, some with the normal 46 chromosomes and others with 47, due to the extra chromosome 21.
• Translocation: Accounting for 3-4% of cases, this occurs when part of chromosome 21 attaches to another chromosome, either before or during conception. Children with this type of Down syndrome have two normal copies of chromosome 21, along with additional material from chromosome 21 attached to another chromosome.

Risk Factors of Down Syndrome

• Advanced Maternal Age: Women aged 35 and older are at a higher risk of having a child with Down syndrome, with the risk increasing significantly after age 40.
• Family History and Genetic Factors: Parents who have previously had a child with Down syndrome or carry a translocation involving chromosome 21 are at a higher risk of having another child with the condition.

Recognising Characteristics of Down Syndrome

Individuals with Down syndrome exhibit a range of physical and cognitive characteristics.

Diagnosis of Down Syndrome

Down syndrome can be diagnosed using methods of which can be used prenatally and postnatally.

Prenatal Diagnosis (Before birth):

• Screening Tests: These tests assess the likelihood of the foetus having Down syndrome by estimating probabilities.
• Diagnostic Tests: Procedures such as chorionic villus sampling (CVS) and amniocentesis can provide a definitive diagnosis with almost 100% accuracy. However, these tests carry a risk of miscarriage.

Postnatal Diagnosis (At birth):

• Physical Observation: At birth, Down syndrome is often recognised by specific physical traits, though a chromosomal analysis, called a karyotype, is conducted to confirm the diagnosis. Fluorescence in situ hybridisation (FISH) is another genetic test that can rapidly confirm the condition by visualising genetic material in the cells.

Health Complications Associated with Down Syndrome

Individuals with Down syndrome are at an increased risk of certain health complications. However, it is important to recognise that every person with Down syndrome is unique, and not all will face significant health challenges. Many of the related conditions can be effectively managed with medication, surgery, or other treatments. With that being said, some health complications include:

• Heart Defects: Congenital heart disease (CHD) affects nearly half of all babies with Down syndrome, potentially leading to high blood pressure in the lungs and cyanosis.
• Gastrointestinal Issues: These can range from structural abnormalities in the digestive system to difficulties in processing certain foods, necessitating lifelong dietary adjustments.
• Immune Disorders: The weakened immune system in individuals with Down syndrome increases their susceptibility to infections, which require immediate and ongoing medical attention.
• Sleep Apnoea: Many children with Down syndrome experience obstructive sleep apnoea, leading to interruptions in breathing during sleep.
• Spinal Problems: Some children may have misshapen bones in the upper spine, which can press on the spinal cord, increasing the risk of injury.
• Obesity: Youths with Down syndrome are more likely to be overweight or obese, and standard weight management guidelines may need to be adjusted to suit their specific needs.
• Dementia: People with Down syndrome are more likely to experience serious heart conditions, which also increases their risk of developing early-onset dementia.
• Leukaemia: Children with Down syndrome have a higher risk of developing leukaemia, a type of cancer affecting white blood cells, compared to other children. Those diagnosed with leukaemia should undergo appropriate cancer treatment, which often includes chemotherapy.

Managing Down Syndrome

Down syndrome is a lifelong condition, but various treatments and therapies can significantly improve the quality of life for those affected.

Some rehabilitation therapies include:

• Physical Therapy: Activities and exercises to enhance motor skills, strengthen muscles, and improve posture and balance.
• Speech-Language Therapy: Helps improve communication skills and effective language use.
• Occupational Therapy: Assist in identifying ways to adapt daily tasks and environments to suit individual needs and capabilities.
• Emotional and Behavioural Therapy: Helps in developing constructive responses to various behaviours.

Preventing Down Syndrome

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

Make an Appointment at Gleneagles Hospitals

If your child has Down syndrome or you are seeking a prenatal diagnosis, our experienced team of General Paediatricians at Gleneagles Hospitals is here to provide the best possible care.

Get in touch with us to book an appointment today for a consultation, or visit our Paediatric Care Department at your nearest Gleneagles Hospital.