Down 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. The lifespan for people with Down syndrome has increased dramatically in recent decades from 25 in 1983 to 60 today.
Recent medical advances, as well as cultural and institutional support for people with Down syndrome and their families, provide many opportunities to help overcome the challenges of this condition.
What causes Down syndrome?
In every cell in the human body, there is a nucleus, where genetic material is stored in genes. Genes carry the codes responsible for all of our inherited traits and are grouped along rod-like structures called chromosomes. Typically, the nucleus of each cell contains 23 pairs of chromosomes, half of which are inherited from each parent. Down syndrome occurs when 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.
The chance of having a baby with Down syndrome increases with the mother’s age; however about half of the babies born with Down syndrome are born to mothers under 35 years old simply because more young women are having babies. Research shows that paternal age also affects. Fathers over 40 had twice the chance of having a child with Down syndrome. People with a family history of Down syndrome and people who carry the genetic translocation are also likely to have a child with Down syndrome.
Down syndrome has nothing to do with race, nationality, socioeconomic status, religion, or anything the mother or father did during pregnancy.
Types of Down syndrome
There are three types of Down syndrome:
Trisomy 21
This is the most common form of Down syndrome and accounts for 95% of cases. It is usually caused by an error in cell division called “nondisjunction.” Nondisjunction results in an embryo with three copies of chromosome 21 instead of the usual two. Before or at conception, a pair of 21st chromosomes in either the sperm or the egg fails to separate. As the embryo develops, the extra chromosome is replicated in every cell of the body.
Mosaicism
Mosaicism is the least common form of Down syndrome and accounts for only about 1% of all cases of Down syndrome. It is diagnosed when there is a mixture of two types of cells, some containing the usual 46 chromosomes and some containing 47. Those cells with 47 chromosomes contain an extra chromosome 21. People with mosaic Down syndrome tend to have fewer symptoms than those with trisomy 21.
Translocation
In translocation, which accounts for about 4% of cases of Down syndrome, the total number of chromosomes in the cells remains 46; however, an additional full partial copy of chromosome 21 attaches to another chromosome, usually chromosome 14. The presence of the extra full or partial chromosome 21 causes the characteristics of Down syndrome.
What are the symptoms of Down syndrome?
At birth, babies with Down syndrome usually have certain characteristic signs, including;
Flat facial features
Small head and ears
Short neck
Bulging tongue
Eyes that slant upward
Atypically shaped ears
Poor muscle tone
A single deep crease across the center of the palm
An infant with Down syndrome can be born of 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 social development delays may mean that the child could have;
Impressive behavior
Poor judgment
Short attention span
Slow learning capabilities
Complications often accompany Down syndrome. These may include;
Congenital heart defects
Hearing loss
Poor vision
Cataracts (clouded eyes)
Hip problems, such as dislocations
Leukemia
Sleep apnea (interrupted breathing during sleep)
Dementia (thought and memory problem)
Hypothyroidism (low thyroid function)
Obesity
Late tooth growth, causing problems with chewing
Alzheimer’s disease later in life
People with Down syndrome are also more prone to infection. They may struggle with respiratory infections, urinary tract infections, and skin infections.
How is Down syndrome diagnosed?
There are two categories of tests for Down syndrome that can be performed before a baby is born; screening tests and diagnostic tests. Prenatal screens estimate the chance of the fetus having Down syndrome. The additional test to detect Down syndrome may include Amniocentesis, Chorionic villus sampling (CVS), and percutaneous umbilical blood sampling (PUBS, or cordocentesis).
At birth, a physical examination of your baby and order a blood test called a karyotype to confirm Down syndrome.
Treating Down syndrome
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.
In these programs, physiotherapists, specialist teachers will help to learn sensory skills, social skills, self-help skills, motor skills, and language and cognitive abilities. A stimulating home environment and good health care and positive support from family, friends, and the community enable people with Down syndrome to lead fulfilling and productive lives.
Importance of early intervention
The first years of life are a critical time in a child’s development. Children with Down syndrome typically face delays in certain areas of development, so early intervention is highly recommended. It can begin anytime after birth, but the sooner it starts, the better. Early intervention is a systematic program of therapy, exercises, and activities designed to address developmental delays that may be experienced by children with Down syndrome or other disabilities. The most common early intervention services for babies with Down syndrome are physical therapy, speech and language therapy, and occupational therapy.
Dilki Karunathilake
References
https://www.ndss.org/about-down-syndrome/down-syndrome-facts/
https://www.globaldownsyndrome.org/about-down-syndrome/facts-about-down-syndrome/
https://www.ndss.org/about-down-syndrome/down-syndrome/
https://www.healthline.com/health/down-syndrome#screening
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