What is Down Syndrome?

What is Down Syndrome?

Down syndrome or Down's Syndrome, trisomy 21 (primarily in the United Kingdom) is a chromosomal condition caused by the presence of all (or part) of an extra 21st chromosome (pictured at right). It is named for John Langdon Down, the British physician who first described the syndrome in 1866. It was later identified as chromosome 21 trisomy by Jerome Lejeune in 1959.

As noted above, Down syndrome is a chromosomal condition characterized by the presence of an extra copy of genetic material on the 21st chromosome, either in whole (trisomy 21) or part (such as due to translocations). The exact effect and extent of the extra copy vary greatly among people, depending on genetic history, and pure chance. The incidence of Down syndrome is estimated at 1 per 733 births, although it is statistically more common with older parents (both mother and father) due to increased mutagenic exposures upon some older parents' reproductive cells. Down syndrome occurs in all human populations and analogous effects have been found in other species such as chimpanzees and mice.

Often Down syndrome is associated with some impairment of cognitive ability and physical growth, and a particular set of facial characteristics. Many children with Down syndrome who received family support, enrichment therapies, and tutoring have been known to graduate from high school and college, and enjoy employment in the work force. On average, the IQ of a child with Down syndrome is around 50, compared to normal children with an IQ of 100. It should be noted that a small number have a severe to high degree of intellectual disability.



Chris Burke

 Many of the common physical features associated with Down syndrome may also appear in people with standard sets of chromosomes including microgenia (an abnormally small chin), unusually round face, macroglossia (protruding or oversized tongue), an almond shape to the eyes caused by an epicanthic fold of the eyelid, upslanting palpebral fissures (the separation between the upper and lower eyelids), shorter limbs, a single transverse palmar crease (a single instead of a double crease across one or both palms, poor muscle tone, and a larger than normal space between the big and second toes. Health concerns for persons with Down syndrome include a higher risk for congenital heart defects, gastroesophageal reflux disease (GERD), recurrent ear infections, obstructive sleep apnea, and thyroid dysfunction.

 

It has been proven that early childhood intervention, screening for common problems, medical treatment (where indicated), a conductive family environment, and vocational training can improve the overall development of children with Down syndrome. Additionally, education and proper care will also improve their quality of life, despite genetic limitations.

 

 

Until next time . . .