WIP 01 What Causes Down Syndrome ?
Down syndrome or trisomy 21 (or Down's Syndrome in British English[1] and WHO ICD) is a chromosomal disorder caused by the presence of all or part of an extra 21st chromosome.

What are the Effects of Down Syndrome ?
The condition is characterized by a combination of major and minor differences in structure. Often Down syndrome is associated with some impairment of cognitive ability and physical growth as well as facial appearance.

Individuals with Down syndrome tend to have a lower than average cognitive ability, often ranging from mild to moderate learning disabilities. A small number have severe to profound mental disability.

Many of the common physical features of Down syndrome also appear in people with a standard set of chromosomes. They may include a single transverse palmar crease (a single instead of a double crease across one or both palms, also called the Simian crease), an almond shape to the eyes caused by an epicanthic fold of the eyelid, upslanting palpebral fissures, shorter limbs, poor muscle tone, a larger than normal space between the big and second toes, and protruding tongue. Health concerns for individuals with Down syndrome include a higher risk for congenital heart defects, gastroesophageal reflux disease, recurrent ear infections, obstructive sleep apnea, and thyroid dysfunctions.

Can Down Syndrome be identified eariler ?
Down syndrome can be identified during pregnancy or at birth.

What are the Factors leading to Down Syndrome?
The incidence of Down syndrome is estimated at 1 per 800 to 1,000 births, although these statistics are heavily influenced by the age of the mother. Other factors may also play a role.

from http://en.wikipedia.org/wiki/Down_syndrome