Causes, symptoms, diagnosis and treatment
What is Down syndrome?
Down syndrome is a genetic disorder that causes mild to severe physical and developmental problems.
People with Down syndrome are born with an extra chromosome. Chromosomes are bundles of genes, and your body relies on the right number of them. With Down syndrome, that extra chromosome leads to a series of issues that affect you both mentally and physically.
Down syndrome is a disease that lasts a lifetime. Although it cannot be cured, doctors know more about it than ever before. If your child has it, getting the right care early on can make a big difference in helping them live a full and meaningful life.
Symptoms of Down syndrome
Down syndrome can have many effects, and each person is different. Some will grow up to live almost entirely on their own, while others will need more help taking care of themselves.
Mental abilities vary, but most people with Down syndrome have mild to moderate problems with thinking, reasoning, and understanding. They will learn and acquire new skills throughout their lives, but it may take longer for them to achieve important goals like walking, speaking, and developing social skills.
People with Down syndrome tend to have certain physical characteristics in common. These may include:
- Eyes that tilt to the outer corner
- Small ears
- Flat noses
- Protruding tongue
- Small white spots in the colored part of the eyes
- Short neck
- Little hands and feet
- Small size
- Loose joints
- Poor muscle tone
Many people with Down syndrome do not have other health problems, but some do. Common ailments include heart problems and impaired hearing and vision.
Causes and risk factors of Down syndrome
For most people, every cell in your body has 23 pairs of chromosomes. One chromosome of each pair comes from your mother and the other from your father.
But with Down syndrome something is wrong and you get an extra copy of chromosome 21. This means that you have three copies instead of two resulting in the symptoms of Down syndrome. Doctors don’t know why this is happening. There is no connection with anything in the environment or anything the parents did or did not do.
Although doctors don’t know what causes it, they do know that women 35 and older are more likely to have a baby with Down syndrome. If you have had a child with Down syndrome in the past, you are more likely to have another with it as well.
It’s not common, but Down syndrome can be passed from parent to child. Sometimes a parent has what experts call “translocated” genes. This means that some of their genes are not in their normal place, possibly on a different chromosome than where they usually are.
The parent does not have Down syndrome because they have the right number of genes, but their child can have what is called “translocation Down syndrome“. Not all people with Down syndrome with translocation get it from their parents – it can also happen by chance.
Types of Down syndrome
There are three types of Down syndrome:
- Trisomy 21. This is by far the most common type, where every cell in the body has three copies of chromosome 21 instead of two.
- Down syndrome with translocation. In this type, each cell has part of an extra 21 chromosome, or an entirely extra chromosome. But he is attached to another chromosome instead of being alone.
- Mosaic Down Syndrome. This is the rarest type, where only certain cells have an extra 21 chromosome.
You can’t tell what type of Down syndrome a person has just by their appearance. The effects of the three types are very similar, but a person with mosaic Down syndrome may not have as many symptoms because fewer cells have the extra chromosome.
Diagnosis of Down syndrome
A doctor may suspect Down syndrome in a newborn baby based on how the baby looks. This can be confirmed by a blood test called a karyotype test which aligns the chromosomes and will show if there is an extra 21 chromosome.
Screening for Down syndrome during pregnancy
Routine tests done during pregnancy can check whether your baby is likely to have Down syndrome. If these results are positive or you are at high risk, you may choose to have additional, more invasive tests to be sure.
In the first trimester, you may have:
- Blood tests. Your doctor will measure the levels of a protein called PAPP-A and a hormone called hCG in your blood. Anything outside the normal range could mean a problem with the baby. If you are at high risk for Down syndrome, they may also look for the baby’s DNA in your blood, which they can examine for chromosomal abnormalities.
- Ultrasound. Your doctor will look at a photo of your baby and measure the folds of fabric on the back of his neck. Babies with Down syndrome tend to have more fluid.
In the second trimester, you may have:
- Blood tests. A triple or quad screen test measures other substances in your blood, including AFP protein and the hormone estriol. These levels, combined with the first trimester test results, give your doctor a good estimate of your baby’s chances of having Down syndrome.
- Ultrasound. When your baby is more developed, an improved ultrasound may show some of the physical characteristics of Down syndrome.
Other types of tests can diagnose Down syndrome before your baby is born by checking a sample of their DNA for an extra chromosome 21:
- Chorionic villus sampling (CVS). This can be done during the first trimester, using cells taken from the placenta.
- Amniocentesis. Fluid is taken from the amniotic sac surrounding the baby, usually during the second trimester.
- Percutaneous Cord Blood Sampling (PUBS). This is also done in the second trimester using blood drawn from the umbilical cord.
Treatments for Down syndrome
There is no specific treatment for Down syndrome. But there is a wide range of physical and developmental therapies designed to help people with Down syndrome reach their full potential. The earlier you start them, the better. Each child will have different needs. Yours can benefit from:
- Physiotherapy, occupational therapy and speech therapy
- Special education services
- Social and recreational activities
- Programs that provide vocational training and teach self-care skills
You will also work closely with your child’s doctor to monitor and manage any health issues associated with the disease.
Complications of Down syndrome
Babies with Down’s syndrome can be born with other physical problems, and they are at higher risk of developing certain health problems later in life.
Possible complications of Down syndrome include: