Children with down syndrome they have an extra (third) copy of the 21st chromosome (Trisomy 21), the smallest human chromosome. Normally, human's cell contains 23 pairs of chromosomes which carry all of a person's genetic information.
Down Syndrome is a genetic condition, parents of down syndrome children don't have any symptoms
themselves. Advanced maternal age is associated with a high incidence of Trisomy 21, the chance of having a Down syndrome birth depends on the mother's age.
Chance of baby having down syndrome has been linked to the mother's age. Womens are who delivery her first child when her age under 25 years old, the odds of having a child with Down syndrome are about 1 in 1,400. The odds at age 35 are about 1 in 350 and at age 40, the odds are about 1 in 100.
The extra genes result in certain characteristics including some degree of mental retardation, or cognitive disability and other developmental delays. Physical findings do change as the child ages and certain features may become more or less noticeable with time.
Generally, sign and symptom
of down syndrome are oblique eye fissures with epicanthic skin folds on the inner corner of the eyes, a single palmar fold (also known as a simian crease), muscle hypotonia (poor muscle tone), a short neck, a flat nasal bridge, a protruding tongue (due to small oral cavity, and an enlarged tongue near the tonsils), white spots on the iris known as Brushfield spots, excessive flexibility in joints, congenital heart defects, excessive space between large toe and second toe, a single flexion furrow of the fifth finger, and a higher number of ulnar loop dermatoglyphs.
Children with Down syndrome can have serious abnormalities affecting any body system, Infants born with Down syndrome may be of average size, but typically they grow slowly and remain smaller than other children of similar age.