Louis Center for Children with Down syndrome, or Down's syndrome, trisomy 21, is a chromosomal condition caused by the presence of all or part of an extra 21st chromosome. It is named after John Langdon Down, the British physician who described the syndrome in 1866. The condition was clinically described earlier in the 19th century by Jean Etienne Dominique Esquirol in 1838 and Edouard
Seguin in 1844. Down syndrome was identified as a chromosome 21 trisomy by Dr. Jérôme Lejeune in 1959. Down syndrome in a fetus can be identified through chorionic villus sampling or amniocentesis during pregnancy, or in a baby at birth.
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 effects 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 due to increased mutagenic
exposures upon some older parents' reproductive cells. Other factors may also
play a role. 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. Individuals
with Down syndrome tend to have a lower-than-average cognitive ability, often
ranging from mild to moderate disabilities. Many children with Down syndrome who
have received family support, enrichment therapies, and tutoring have been known
to graduate from high school and college, and enjoy employment in the work
force. The average IQ of children with Down syndrome is around 50, compared to
normal children with an IQ of 100. A small number have a severe to high degree of intellectual disability.
Individuals with Down syndrome may have some or all of the following physical characteristics: microgenia (an abnormally small chin), an 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 individuals with Down syndrome include a higher risk for congenital heart defects, gastroesophageal
reflux disease, recurrent ear infections that may lead to hearing loss,
obstructive sleep apnea, thyroid dysfunctions, and obesity.
Early childhood intervention, screening for common problems, medical
treatment where indicated, a conducive family environment, and vocational
training can improve the overall development of children with Down syndrome.
Education and proper care will improve quality of life significantly, despite
Louis Center Seremban, N.S. Malaysia Phone 06 631 6971