Down Syndrome – Symptoms and Causes

Overview

Down syndrome is a genetic condition that happens when a person has an extra full or partial copy of chromosome 21. This extra genetic material leads to specific developmental changes and physical features.

The condition is named after John Langdon Down, the English physician who first described it. A syndrome means a group of symptoms that occur together in a recognizable pattern.

People with Down syndrome experience varying levels of severity. It causes lifelong intellectual disability and developmental delays, making it the most common genetic chromosomal cause of intellectual disabilities in children.

Many individuals with Down syndrome also have other medical issues, particularly affecting the heart and digestive system. With proper support, people with Down syndrome can lead fulfilling and meaningful lives despite the challenges they face.

Signs and Symptoms

Growth and Learning Delays

Children with Down syndrome often reach milestones more slowly than their peers. They may take extra time to learn sitting, walking, and talking. This slower pace of development affects most children with this condition.

Physical therapy, speech therapy, and occupational therapy can be very helpful. These therapies can improve movement skills and speech abilities. With the right support, children can make steady progress at their own pace.

Learning Challenges

Most people with Down syndrome have mild to moderate learning difficulties. These challenges affect several areas:

• Memory issues
• Trouble learning new skills
• Difficulty focusing on tasks
• Problems with decision-making

Speech and language typically develop later than in other children. Early support programs and special education services make a big difference.

These programs help children and teens reach their potential. Adults with Down syndrome can also benefit from support services to live full, meaningful lives.

When to Talk to a Healthcare Provider

Down syndrome is usually found before or right after birth. However, you should speak with your doctor if you have:

• Questions about your pregnancy
• Concerns about your child’s growth
• Worries about development milestones
• Need for information about support services

Physical traits of Down syndrome may include:

Common Features	Description
Face	Flattened face, small nose with flat bridge
Head and Neck	Small head, short neck
Eyes	Upward slanting eyelids, skin fold over inner eye corner, white spots on iris (Brushfield’s spots)
Mouth	Tongue that may protrude
Ears	Small, rounded ears
Hands and Feet	Small hands with single palm crease, short fingers, small feet with gap between first and second toes
Height	Typically shorter than peers
Muscle tone	Lower muscle tone in infancy, flexible joints

Each person with Down syndrome is unique. Health issues vary from person to person, with some having few health problems while others face more challenges like heart conditions present at birth.

What Causes Down Syndrome?

Down syndrome happens when there are changes in chromosome 21. People usually have 23 pairs of chromosomes in each cell. These chromosomes come from both parents—one from the egg and one from the sperm.

With Down syndrome, something different happens with chromosome 21. The person ends up with extra genetic material from this chromosome. This extra material affects how the body and brain grow and develop.

Is Down Syndrome Inherited?

Most cases of Down syndrome are not inherited from parents. They happen by chance during cell division when:

• Egg cells form in the mother
• Sperm cells form in the father
• The fertilized egg begins dividing

There are three main ways Down syndrome can occur:

1. Trisomy 21 (95% of cases)
   • Person has three copies of chromosome 21 instead of two
   • The extra chromosome appears in all cells
   • Caused by unusual cell division during egg or sperm formation
2. Mosaic Down Syndrome (rare)
   • Only some cells have the extra chromosome 21
   • Other cells have the normal two copies
   • Happens because of unusual cell division after fertilization
3. Translocation Down Syndrome (uncommon)
   • Part of chromosome 21 attaches to another chromosome
   • Person has two copies of chromosome 21 plus extra material on another chromosome
   • Can happen before or at conception

While most cases happen randomly, translocation Down syndrome can sometimes run in families. In these cases, a parent may have a “balanced translocation.” This means they have rearranged genetic material but no extra chromosome material.

These parents show no signs of Down syndrome themselves but can pass an unbalanced form to their children.

Risk Factors

Several factors can increase the chance of having a baby with Down syndrome:

Age of the Parent

The risk increases as the pregnant person gets older, especially after age 35. This happens because older eggs have a higher chance of dividing incorrectly.

Even though the risk is higher for older parents, most babies with Down syndrome are born to people under 35 because this age group has more babies overall.

Genetic Translocation Carriers

When either parent carries a specific genetic arrangement called translocation, they can pass it to their children, increasing the risk of Down syndrome.

Previous Child with Down Syndrome:

Parents who already have a child with Down syndrome face a higher risk with future pregnancies. This is true for both parents of a child with Down syndrome and parents who have the translocation themselves.

Health Issues

People with Down syndrome can now live much longer than before. Better healthcare has helped a lot. Today, many live past 60 years old. How long someone lives depends on how serious their health problems are.

Most people with Down syndrome face some health challenges. These can range from mild to severe. Some have very few health issues, while others deal with several serious conditions.

Heart problems affect about half of all children born with Down syndrome. These issues can be dangerous and sometimes require surgery when babies are very young.

Digestive system problems are common. These might include:

• Changes in stomach or intestine structure
• Intestinal blockages
• Heartburn (GERD)
• Celiac disease

The immune system works differently in people with Down syndrome. This means they get sick more easily and face higher risks of:

• Autoimmune disorders
• Certain cancers
• Infections like pneumonia

Sleep apnea happens more often because of soft tissue changes and spine differences. This causes breathing problems during sleep.

Weight issues are more common. People with Down syndrome tend to gain weight more easily than others.

Spine problems can be serious. Some people have atlantoaxial instability, where the top two neck bones don’t line up right. This renders neck-bending activities hazardous.

Children with Down syndrome have a higher chance of getting leukemia compared to other children.

Alzheimer’s disease is much more common and starts earlier—often around age 50.

Other health issues include:

• Thyroid problems
• Dental issues
• Seizures
• Ear infections
• Hearing and vision problems
• Mental health conditions like depression and anxiety
• Autism
• ADHD

Prevention

No method can prevent Down syndrome. If you face a higher risk or already have a child with this condition, speaking with a genetic counselor before pregnancy might be helpful.

Genetic counselors offer valuable support. They explain your chances of having a child with Down syndrome. They also discuss available prenatal testing options.

They can provide information that helps you make informed decisions about family planning based on your specific situation.