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Understanding Down’s Syndrome

  • Karyotype of a person with Down's Syndrome
    Karyotype of a person with Down's Syndrome

Photo: Vidisha Kulkarni / Research Matters

Saylee Agavane from Pune is a Kathak dancer who started learning the classical form of art at the age of 9. During the 17 years of her career as a classical dancer, Saylee has won numerous awards for her performances. Today, she runs her own school where she teaches Kathak to others. Wondering what makes her achievement stand out? She is one of the many with Down’s syndrome, the most common genetic disorder. In recognition of her self-advocacy and courage to beat all odds and excel in her field of choice, she is awarded the ‘2017 World Down Syndrome Day Award’, announced by the Down Syndrome International (DSi).

March 21st of every year is observed as ‘World Down Syndrome Day’, for all of us to spare a thought about people with Down’s syndrome and those that live, care and work with them throughout the world. Every year, organizations around the world mark this day with efforts to raise awareness, rally communities and advocate policymakers about the rights, inclusion and well being of those having this disorder.

Today, 10 in 10,000 babies are born with Down’s syndrome and this number has been increasing in the recent years. According to a report from Down Syndrome Association of India, the prevalence of this disorder in India is estimated at 1 in 800 births.

History has recorded many individuals with characteristics similar to Down’s syndrome. However, it wasn’t until the late nineteenth century, that this disorder was described as a distinct and separate entity. John Langdon Down, an English physician, characterized this disorder and published an accurate description of a person with Down’s syndrome. It was identified as a genetic disease after the French physician Jérôme Lejeune, in 1959, observed 47 chromosomes in the cells of individuals with Down’s syndrome.

The science behind Down’s syndrome

Down’s syndrome, also called ‘Trisomy 21’, is a genetic disorder characterized by physical and mental disabilities. Babies born with this disorder also typically have poor immune function, stunted growth, and an increased risk of a number of other health problems like congenital heart defects, epilepsy, leukemia, thyroid diseases, respiratory infections, etc.

But what causes Down’s syndrome? It is caused due to an accidental aberration of one of the chromosomes in our cells. Chromosomes are thread-like structures composed of DNA (the genetic material) and other proteins. They are present in every cell of our body and carry the information needed for that cell to develop. Each cell normally has 46 such chromosomes arranged as 23 pairs - 22 pairs similar in males and females (autosomes) and one pair of sex chromosomes (‘X’ and ‘Y’). Each pair is derived from one of the parents – one from the father and one from the mother.

Out of the 23 pairs of chromosomes, the chromosome number 21, like the rest, typically is present as a pair with each set inherited from one of the parents. It is the smallest human chromosome and represents 1.5% to 2% of the total DNA in cells. But in case of people with Down’s syndrome, there is an extra full or partial copy of chromosome 21, making it three sets in total, rather then two. This extra chromosome alters the course of normal development, causing a variety of physical and mental defects associated with this disorder. In fact, the date March 21 (21/03) was chosen to be ‘World Down Syndrome Day’ as it signifies the triplication of chromosome 21, the cause of the disorder.

Diagnosis and cure of Down’s syndrome

With the advent of imaging technologies, Down’s syndrome can be diagnosed in babies before they are even born. Regular screening of the foetus during pregnancy (prenatal screening) enables detecting any abnormality in the unborn baby’s growth, which could be a sign of this disorder. After a baby is born, doctors look out for physical characteristics like reduced muscle tone, flat facial profile, small nose and slanting eyes, to make initial diagnosis. Sometimes, a sample of the baby’s blood is taken for chromosomal analysis to confirm the condition.
  
While scientists around the world are uncovering the cause behind this accidental chromosomal abnormality, the cure for Down’s syndrome is still elusive. However, resulting conditions and complications due to this disorder, like respiratory infections, thyroid disorders and heart defects, can be treated, thus improving the quality of life for those affected by this disorder. Studies estimate that with improved treatments and care, a person with Down’s syndrome today has an increased life expectancy of about 55 years. 

A breakthrough in understanding Down’s syndrome came in the year 2000, when an international team of scientists successfully identified and catalogued each of the approximately 329 genes on chromosome 21. This accomplishment has now opened the door to great advances in Down’s syndrome research, accelerating the search for a cure.

How can the society help?

While scientists are busy looking out for a remedy, the society on the whole can help to a great extent in easing the lives of those diagnosed with this disorder. Studies have shown that a caring and nourishing environment at home, along with specialized education tailored to their needs, positively influences the development of children with Down’s syndrome.

Today, various national and international organizations provide the required support, information, resources, counseling and guidance to individuals with Down’s syndrome and to their parents or caregivers. Speech therapies, occupational therapies and physiotherapies are formulated to specifically address the challenges such individuals face during their growing years. An early intervention can inculcate the basic physical, cognitive, language, social and self-help skills that lay the foundation for future progress of these individuals.

Today, people with Down’s syndrome are excelling in a wide variety of fields as dancers, actors, painters, sportspersons, musicians, etc. There are plenty of job opportunities and vocational training available to help them integrate with the society, be self-reliant and inspire others who look up to them as role models. Ultimately, the onus is on each of us to give people with this unfortunate disorder a chance to achieve basic human dignity.

Organizations like the Down Syndrome International (DSi) organizes campaigns and conferences to spread awareness about this disorder and discuss on ways to improve an individual’s quality of life. In India, societies like the Down Syndrome Federation of India have taken a step ahead and provide services like counseling and special education to those who are affected by Down’s syndrome.

“It's not our disabilities, it's our abilities that count”, said Chris Burke, a former American actor and folk singer who lives with Down’s syndrome. As a society, it is the responsibility of each of us to give them a chance to make their abilities count.