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Down syndrome (sometimes called Down’s syndrome) is a condition in which a child is born with an extra copy of their 21st chromosome — hence its other name, trisomy 21. This causes physical and mental developmental delays and disabilities.
Many of the disabilities are lifelong, and they can also shorten life expectancy. However, people with Down syndrome can live healthy and fulfilling lives. Recent medical advances, as well as cultural and institutional support for people with Down syndrome and their families, provides many opportunities to help overcome the challenges of this condition.
In all cases of reproduction, both parents pass their genes on to their children. These genes are carried in chromosomes. When the baby’s cells develop, each cell is supposed to receive 23 pairs of chromosomes, for 46 chromosomes total. Half of the chromosomes are from the mother, and half are from the father.
In children with Down syndrome, one of the chromosomes doesn’t separate properly. The baby ends up with three copies, or an extra partial copy, of chromosome 21, instead of two. This extra chromosome causes problems as the brain and physical features develop.
According to the National Down Syndrome Society (NDSS), about 1 in 700 babies in the United States is born with Down syndrome. It’s the most common genetic disorder in the United States.
There are three types of Down syndrome:
Trisomy 21 means there’s an extra copy of chromosome 21 in every cell. This is the most common form of Down syndrome.
Mosaicism occurs when a child is born with an extra chromosome in some but not all of their cells. People with mosaic Down syndrome tend to have fewer symptoms than those with trisomy 21.
In this type of Down syndrome, children have only an extra part of chromosome 21. There are 46 total chromosomes. However, one of them has an extra piece of chromosome 21 attached.
Certain parents have a greater risk of giving birth to a child with Down syndrome. According to the Centers for Disease and Prevention, mothers aged 35 and older are more likely to have a baby with Down syndrome than younger mothers. The risk increases the older the mother is.
Research shows that paternal age also has an effect. One 2003 study found that fathers over 40 had twice the risk of having a child with Down syndrome.
Other parents who are at greater risk of having a child with Down syndrome include:
It’s important to remember that no one of these factors mean that you’ll definitely have a baby with Down syndrome. However, statistically and over a large population, they can put you at higher risk.
Though the likelihood of carrying a baby with Down syndrome can be estimated by screening during pregnancy, you won’t experience any symptoms of carrying a child with Down syndrome.
At birth, babies with Down syndrome usually have certain characteristic signs, including:
An infant with Down syndrome can be born an average size, but will develop more slowly than a child without the condition.
People with Down syndrome usually have some degree of developmental disability, but it’s often mild to moderate. Mental and social development delays may mean that the child could have:
Medical complications often accompany Down syndrome. These may include:
Screening for Down syndrome is offered as a routine part of prenatal care in the United States. If you’re a woman over 35, your baby’s father is over 40, or there’s a family history of Down syndrome, you may want to get an evaluation.
An ultrasound evaluation and blood tests can look for Down syndrome in your fetus. These tests have a higher false-positive rate than tests done at later pregnancy stages. If results aren’t normal, your doctor may follow up with an amniocentesis after your 15th week of pregnancy.
An ultrasound and quadruple marker screen (QMS) test can help identify Down syndrome and other defects in the brain and spinal cord. This test is done between 15 and 20 weeks of pregnancy.
If any of these tests aren’t normal, you’ll be considered at high risk for birth defects.
Your doctor may order additional tests to detect Down syndrome in your baby. These may include:
Some women choose not to undergo these tests because of the risk of miscarriage. They’d rather risk having a child with Down syndrome than lose the pregnancy.
At birth, your doctor will:
There’s no cure for Down syndrome, but there’s a wide variety of support and educational programs that can help both people with the condition and their families. The NDSS is just one place to look for programs nationwide.
Available programs start with interventions in infancy. Federal law requires that states offer therapy programs for qualifying families. In these programs, special education teachers and therapists will help your child learn:
Children with Down syndrome often meet age-related milestones. However, they may learn more slowly than other children.
School is an important part of the life of a child with Down syndrome, regardless of intellectual ability. Public and private schools support people with Down syndrome and their families with integrated classrooms and special education opportunities. Schooling allows valuable socialization and helps students with Down syndrome build important life skills.
The lifespan for people with Down syndrome has improved dramatically in recent decades. In 1960, a baby born with Down syndrome often didn’t see their 10th birthday. Today, life expectancy for people with Down syndrome has reached an average of 50 to 60 years.
If you’re raising a child with Down syndrome, you’ll need a close relationship with medical professionals who understand the condition’s unique challenges. In addition to larger concerns — like heart defects and leukemia — people with Down syndrome may need to be guarded from common infections such as colds.
People with Down syndrome are living longer and richer lives now more than ever. Though they can often face a unique set of challenges, they can also overcome those obstacles and thrive. Building a strong support network of experienced professionals and understanding family and friends is crucial for the success of people with Down syndrome and their families.
Written by: The Healthline Editorial Teamon: Nov 14, 2017
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