Down syndrome is a congenital condition that is a result of chromosomal irregularities where the child has physical, emotional and developmental difficulties. The severity of it ranges from mild to moderate. While the disabilities are lifelong, many people with Down syndrome live fulfilling and healthy lives. Recent technological advances not only help in screening Down syndrome in pregnancy, but they also help deal with the challenges of whether a child has Down syndrome. Read below to learn about the causes, signs, screening, treatment and more.
During reproduction, the genes of both parents are passed to the children. The chromosomes carry these genes; when the fetus's cells develop, each cell gets 46 chromosomes or 23 pairs—half from the mother and half from the father. In a child with Down syndrome, one of the chromosomes, chromosome 21, has an extra copy and is called Trisomy 21. This is because the 21st chromosomal pair has an extra strand, resulting in 3 instead of 2 strands, so the total now is 47 instead of 46. This irregularity happens during the conception stage in the ovum cells when the chromosomes begin to separate. It mainly affects ovum cells in adult women, where fibres needed for separating cells have been retained for extended periods, resulting in decreased flexibility. This is one of the most common causes of Down syndrome in people and accounts for 95% of cases.
The following common type of Down syndrome is chromosomal translocation, which is responsible for 4% of Down syndrome pregnancies. This happens when the chromosomes are present in a different location than where they should be. For example, the 15th pair of chromosomes is present in the 21st pair.
The mosaic condition is one of the least common Down syndrome pregnancies where the 46th and the 47th strands are present in a fetus. This accounts for 1% of pregnancies with Down syndrome.
● There is a 1 in 250 chance of children of women who are pregnant after 35 years of age. The older she is when she is pregnant, the greater the risk of a child having Down syndrome.
● A woman who has given birth to a child with this condition has a greater chance of giving birth to another child with Down syndrome from any further pregnancies.
● Another factor increasing the risk is the family history of this condition. For example, sisters, brothers, or blood relatives are at risk.
● Women who have had an ultrasound scan that showed Down syndrome-related markers are also at risk.
It is essential to note that having any of the above factors means that the baby will have Down syndrome. However, statistically, it may increase the risk that may cause this condition.
The chances of the baby having Down syndrome can be estimated during pregnancy while screening, but there won't be any signs for a pregnant woman that she is having a baby with this condition. It is only at birth that the Down syndrome symptoms are seen, which includes:
● Small ears and head
● Flat facial features
● Bulging tongue
● Short neck with extra skin at the back
● Upward slanting eyes
● Poor muscle tone
● Short height
● Outer ear anomalies
A child with Down syndrome may be born with an average weight and height but will have developmental delays. People with this condition typically have some developmental disability, which is mild to moderate. This means these people have:
● Slow learning capacity
● Short attention span
● Poor judgement
● Impulsive behaviour
Apart from the above, they may have medical complications, which include:
● Poor vision
● Clouded eyes (Cataract)
● Congenital heart problems
● Hearing loss
● Sleep apnea
● Low thyroid function
● Obesity
● Chronic constipation
● Leukaemia
● Delayed tooth growth leads to issues with chewing
● Hip problems
● Alzheimer's at a later age
People with this condition are at a higher risk of skin, urinary tract infections, and respiratory infections.
Down syndrome screening is done as part of the routine prenatal care. If the mother is 35 and the father is 40, or the family has a Down syndrome history, it is recommended that you get a Down syndrome test.
● First Trimester: Blood tests and ultrasound scans can be performed in the first trimester to check for Down syndrome. However, one thing to remember is that a test done in this stage may have a higher false positive rate than one done at a later stage. If test results are not typical, the doctor may recommend an amniocentesis after the 15th week of pregnancy.
● Second Trimester: An ultrasound and QMS (quadruple maker screen) test helps to determine Down syndrome and other brain and spinal cord problems. This is done during 15 to 20 weeks of pregnancy. If the tests are not normal, there is a high risk of congenital disability.
● Tests at birth: A physical examination and a Karyotype (a blood test) are performed to determine Down syndrome.
● Amniocentesis is a test done at 15 weeks. It involves taking an amniotic fluid sample to check the baby's chromosome numbers.
● CVS, Chorionic Villus Sampling, is a test done during pregnancy's 9th to 14th week. Placental cells are taken to check fetal chromosomes.
● PUBS, Percutaneous umbilical blood sampling, is a test done after the 18th week. The umbilical cord blood is taken to check for chromosomal defects. This test carries a risk of miscarriage and is hence done only if needed.
Due to the risk of miscarriage in some of these tests, some women prefer not to have these tests, even if it means having a child with this condition.
There is no treatment to cure this condition. Testing during pregnancy gives you the choice to make informed decisions, including terminating the pregnancy. While there is no cure, many educational and support programs help people with this condition. These programs help children with Down syndrome learn social, sensory, motor, language, cognitive and self-help skills. Children with this condition may reach age-related milestones slower than other children. Still, due to advancements in medicine, they can lead a healthy and fulfilling life with special educational and support programs.
Down syndrome is a lifelong condition, and the extra chromosome cannot be removed. Each person who has this has a unique experience, and it is difficult to tell how a child with Down syndrome will be affected.
There are no symptoms of Down syndrome in pregnancy.
Genetic factors and maternal age at the time of conception are some of the main risk factors for Down syndrome.
Chromosomal Karyotype is a test that is used to confirm Down syndrome.
The error in cell division that causes an extra chromosome 21 copy is the leading cause of Down syndrome.
