English physician John Langdon Down was the first person to describe Down syndrome in 1862 and help differentiate the condition from mental disability. He used the term “mongoloid” to describe the condition because of his opinion that children with Down syndrome have physical features similar to Mongolian people. In 1959, French physician Jerome Lejeune found that the “mongoloid” features were the result of a chromosomal abnormality—three instead of two copies of chromosome 21. The use of the term “mongloid” ever since became less and less common while the term ‘trisomy 21’ began to gain usage to describe people with this condition.
In recent years, Down syndrome, also known as trisomy 21, has become more common; however, children with Down syndrome are now living longer than in the past. The life expectancy of people with Down syndrome increased dramatically between 1960 and 2007 from an average age of about 10 years to about 47 years in 2007. Down syndrome is one of the most common chromosomal abnormalities in humans. It occurs in about one per 1,000 babies born each year. In 2015, 5.4 million people had Down syndrome.
Causes, Symptoms, and Treatment
Down syndrome is a genetic condition that is caused due to an error in cell division resulting in an extra chromosome 21. People with Down syndrome have 47 chromosomes in their cells instead of 46. Although it is a genetic condition, Down syndrome is not inherited. It is characterized by a variety of distinctive physical features, an increased risk of certain medical problems, and varying degrees of developmental and intellectual delays. Birth defects such as hypothyroidism, heart defects, vision problems, blood disorders, infections, poor muscle tone, and epilepsy etc. are common in people with Down syndrome and lead to physical and mental disabilities. Many of the disabilities are life-long, and they may shorten life expectancy as well.
Common Down syndrome features include typical physical appearance marked by flattened head in back, skin folds on the eyelids, flattened nose bridge, protruding tongue, short and broad hands, and a short neck. Besides, there is decreased or poor muscle tone along with mental and social development delays, short attention span, slow learning, and delayed language and speech development. The average IQ of people with Down syndrome ranges between 50 and 60, although IQ scores of 120 have also been found in some people with this syndrome. Children with Down syndrome usually are diagnosed before or at birth. There is no treatment to reverse the genetic abnormality that causes Down syndrome, so Down syndrome cure is not possible. However, many of the associated medical and developmental conditions can be treated to improve the child’s development, enhance the person’s quality of life, and increase his or her life expectancy.
Several health care professionals may be required to correctly assess and layout the treatment course for an individual with Down syndrome. Surgery may be required for cardiac or gastrointestinal problems. Conventional interventions such as physiotherapy and speech-and-language therapy facilitate the development of optimal movement-and-speech patterns in children with Down syndrome.
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