Down syndrome

Some babies are born with extra parts in their cells.

This happens by chance. It can change how they grow and learn. They might walk or talk later than others. Some may have trouble with their heart or eyes. Good care and school help them live well. They can grow up to do many things.

It is good to help them every day.

Down syndrome is a way of being born with extra parts in your cells.

These parts are called chromosomes. Most people have two copies of chromosome 21. People with Down syndrome have a third copy. This can happen in all cells or just some.

This happens by chance. It is not caused by anything a parent does. It can happen more often if a mother is older.

This extra part changes how a person grows. They may reach milestones, like crawling or walking, later than others. They might have different shapes for their eyes or hands. Some may have heart or ear problems.

There is no cure for Down syndrome. But people can live very good lives. Good care and school help a lot. Some people go to regular classes. Others need special help at school. Many people grow up to work and be part of their towns.

Down syndrome is a common genetic condition that affects how a person grows and learns.

It happens when a person has an extra copy of chromosome 21. Chromosomes are tiny parts inside our cells that carry instructions for our bodies. Most people have two copies of this specific chromosome. In people with Down syndrome, there is a third copy instead.

This extra material can be in every cell or just some cells. This condition is known as Trisomy 21 when it is in all cells.

It is the most common chromosomal abnormality in the world. It happens to about 1 in 1,000 babies born globally.

There are three different ways this extra material can appear in the body. The most common way is called trisomy 21. In this version, the extra chromosome is there from the very start of life. This happens when the egg and sperm combine during conception. Another way is called translocation Down syndrome. This is when extra material from chromosome 21 attaches to a different chromosome. The third way is called mosaic Down syndrome. This affects only 1 to 2 percent of cases. In these cases, the extra chromosome is added later during the embryo stage. This means only some cells in the body have the extra copy.

Doctors have studied this condition for a very long time. A British physician named John Langdon Down gave the syndrome its name. He dedicated his medical work to helping people with this condition. Other people described these features even earlier in history. A French psychiatrist named Jean-Étienne Dominique Esquirol wrote about it in 1838. A French physician named Édouard Séguin also described it in 1844. Scientists did not find the exact genetic cause until 1959. This discovery helped doctors understand how the extra chromosome works.

Down syndrome can change many parts of a person's physical body. Many people have low muscle tone or extra joint flexibility. They may have slanted eyes or small ears. Some people have a single crease across their palm.

About 40 percent of babies with Down syndrome are born with heart disease. Others might have trouble with hearing or vision.

In the United States, about 1 in 700 babies are born with it. In 2015, there were 5.4 million people living with the condition worldwide.

Even though there is no cure, people with Down syndrome live full lives. Proper health care and education are very important for them. Some children go to regular school classes with their peers. Others might need more specialized help to learn. Many adults in the United States do paid work. About 20 percent of adults with Down syndrome have jobs. With good medical care, life expectancy is around 50 to 60 years. People with Down syndrome often have very high social and emotional awareness.

Down syndrome, also known as Trisomy 21, is a genetic disorder. It is the most common chromosomal abnormality in humans. This condition occurs when a person has all or part of a third copy of chromosome 21.

Chromosomes are the structures that carry genetic instructions. Most people have two copies of chromosome 21. In Down syndrome, an extra copy changes how the body and brain develop. This can lead to developmental delays and intellectual disabilities. It also causes specific physical features.

There are three distinct genetic forms of this syndrome. The most common type is trisomy 21. In this form, every cell in the body has an extra copy of chromosome 21. This happens at conception when the egg and sperm combine. The second type is called translocation Down syndrome. This occurs when extra material from chromosome 21 attaches to another chromosome. The third type is mosaic Down syndrome. This affects only 1% to 2% of cases. In these instances, the extra chromosome is added during the embryo stage. Consequently, only some cells in the body carry the extra genetic material.

Medical history shows how our understanding has grown over time. British physician John Langdon Down gave the syndrome its name. He dedicated his medical practice to supporting those with the condition. Earlier descriptions were made by French psychiatrist Jean-Étienne Dominique Esquirol in 1838. French physician Édouard Séguin also described features in 1844. However, the exact genetic cause was not discovered until 1959. This discovery allowed doctors to understand the role of the extra chromosome.

Down syndrome affects many different physical systems. Many individuals have low muscle tone and excessive joint flexibility. Physical traits can include slanted eyes and epicanthal folds.

Some people have a single transverse palmar crease across their hand. About 40% of newborns with Down syndrome have congenital heart disease. This often involves defects in the walls of the heart. Vision and hearing issues are also very common. Hearing problems affect 50% to 90% of children with the condition.

Intellectual and neurological development also follow specific patterns. Most individuals have mild or moderate intellectual disability. Their mental abilities as adults are often similar to an eight- or nine-year-old. However, their social and emotional awareness is often very high. Developmental milestones like crawling and walking often happen later than usual. For example, half of these children walk after 24 months. Some individuals may also face risks for epilepsy or Alzheimer's disease. About 15% of those living 40 years or longer develop Alzheimer's. As people age, the gap between them and their peers may widen.

Statistics show the global impact of this condition. It occurs in about 1 in 1,000 babies born worldwide. In the United States, the rate is about 1 in 700. In 2015, there were 5.4 million people living with Down syndrome globally. The incidence increases with maternal age. For mothers aged 20, the risk is less than 0.1%. For mothers aged 45, the risk rises to 3%. This increase happens by chance and is not caused by specific behaviors.

While there is no cure, support improves quality of life. Proper education and healthcare are essential for success. Some children attend typical school classes. Others require specialized education to meet their needs. In the United States, about 20% of adults in the workforce hold paid jobs. Many of these adults work in sheltered environments. With proper medical care, life expectancy is now around 50 to 60 years in the developed world.