Down syndrome or trisomy 21 is a chromosomal disorder caused by the presence of all or part of an extra 21st chromosome. This name is given after Doctor John Langdon Down in 1866. The chromosome 21 problem was discovered by Jerome Lejeune in 1959. Down syndrome is associated with some impairment of cognitive ability and physical growth as well as facial appearance. Down syndrome in a baby can be identified with amniocentesis during pregnancy or at birth. Individuals with Down syndrome tend to have a lower than average cognitive ability, often ranging from mild to moderate developmental disabilities. 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.

Physical appearance of Down syndrome child varies from child to child. Some require a medical treatment and some led a healthy life.

Cause Normally at the time of conception a baby inherits genetic information from its parents in the form of 46 chromosomes: 23 from the mother and 23 from the father. In most cases of Down syndrome, a child gets an extra chromosome 21 for a total of 47 chromosomes instead of 46. It's this extra genetic material that causes the physical features and developmental delays associated with Down syndrome.

Appearance of Down syndrome child Certain physical features such as a flat facial profile, an upward slant to the eyes, small ears, and a protruding tongue. Low muscle tone is also characteristic of children with DS, at birth, kids with DS are usually of average size, but they tend to grow at a slower rate and remain smaller than their peers. For infants, low muscle tone may contribute to sucking and feeding problems, as well as constipation and other digestive issues. Toddlers and older kids may have delays in speech and self-care skills like feeding, dressing, and toilet teaching.

Screening and Diagnosis To detect Down syndrome in a fetus: screening tests and diagnostic tests. Screening tests are cost-effective and easy to perform. Diagnostic tests are about 99% accurate in detecting Down syndrome and other chromosomal abnormalities. Screening tests include: Nuchal translucency testing, the triple screen or quadruple screen, integrated screen, a genetic ultrasound. Diagnostic tests include: Chorionic villus sampling (CVS), Amniocentesis, Percutaneous umbilical blood sampling.

Getting Help Experts recommend enrolling kids with Down syndrome in early-intervention services as soon as possible. Physical, occupational, and speech therapists and early-childhood educators can work with your child to encourage and accelerate development.