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Everything you need to know about Down syndrome

A guide to Down syndrome including symptoms and diagnosis of this genetic, chromosomal disease.

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/ Source: TODAY
By Ronnie Koenig

Chances are you have met someone with Down syndrome, one of the most common chromosomal conditions. But there's a lot to learn about it beyond its physical traits.

For one thing, individuals with Down syndrome are capable of achieving many things and living full lives. And by knowing more about the genetic disorder, it can only help to ensure an inclusive environment for all individuals with Down syndrome and reverse the stigma associated with having different abilities.

What is Down syndrome?

Down syndrome is a genetic disorder that often results in distinct physical differences and intellectual disability. According to the Centers for Disease Control, each year about 6,000 babies are born with Down syndrome, making it the most common chromosomal disorder. That's about 1 in every 700 newborns. Caused by abnormal cell division that results in extra genetic material on chromosome 21, this extra full or partial chromosome results in the developmental and physical differences seen in those with the disorder.

What causes Down syndrome?

Most of the time, Down syndrome is not inherited. Instead, it is caused by abnormal cell division. These chromosomal abnormalities are much more prevalent in mothers of advanced maternal age — specifically over the age of 35.

Human cells typically contain 23 pairs of chromosomes — one from the mother and one from the father in each pair. When there is an extra chromosome 21, the result is Down syndrome. There are three genetic variations of Down syndrome:

  1. Trisomy 21: This occurs when there is a third copy of chromosome 21. This is the most typical cause of down syndrome.
  2. Mosaic Down syndrome: Only some cells in the person have an extra copy of chromosome 21. This genetic cause is considered rare.
  3. Translocation Down syndrome: This happens when genetic material from chromosome 21 attaches to another chromosome.

There are no known environmental factors thought to cause down syndrome.

Down syndrome symptoms

Down syndrome is usually diagnosed during pregnancy through genetic screening or at birth through diagnostic tests. There are some distinct physical features that typically occur in individuals with Down syndrome:

  • Flattened face
  • Upturned eyelids
  • Protruding tongue
  • Small head
  • Shorter stature

Intellectual disabilities in those with Down syndrome are common and can range from mild or moderate to severe.

Down syndrome risk factors

In most cases, Down syndrome is not inherited. Translocation Down syndrome can be passed from parent to child, but this is rare. In these cases, the parent may have extra genetic material from chromosome 21 but no signs of Down syndrome themselves.

Advanced maternal age is thought to be the greatest risk factor for Down syndrome, as a mother's eggs, when older, have more chance of chromosomal abnormalities. Already having one child with Down syndrome does increase the risk of having another baby with the disorder. A genetic counselor can be helpful in this situation.

Down syndrome complications

Many babies born with Down syndrome also have a congenital heart defect that may require surgery in infancy. Other complications include gastrointestinal problems, an increased risk of developing autoimmune disorders, higher instances of childhood leukemia and a greater possibility of dementia in adults over 50. People with Down syndrome also have weaker muscle tone and a higher likelihood of obesity.

Down syndrome life expectancy

Despite the many complications and challenges, most babies with Down syndrome can grow up to lead productive, fulfilling lives. With early intervention, many children attend mainstream schools and learn the needed skills to live independently as adults. Life expectancy for those with Down syndrome has increased markedly since 1960 when it was very low. Depending on the severity of accompanying health problems, an individual with Down syndrome can expect to live past age 60.

Down syndrome treatment

There is no way to prevent or cure Down syndrome. But through education, support groups and the right team of health care providers, a child with Down syndrome can go on to succeed, achieve and lead a happy life.