Down Syndrome
Down syndrome is a major cause of mental retardation in the world. It is a chromosomal abnormality that causes delays in physical and intellectual development. It is known that one of every 800 to 1000 births is usually affected by this problem.
Also, the statistics tell us that 80% of children born to women under age 35. There is wide variation in physical development, behavior and mental abilities. Most people with Down Syndrome in the range between mild and moderate mental retardation.
Down syndrome was first described in 1866 by John Langdon Down. In 1959, genetic analysis allowed Dr. Jerome Lejeune determine the cause of Down syndrome. People tiene2 copies of each of the 23 chromosomes. In this syndrome, rather than 2 copies of chromosome 21, there are 3 copies. This is where the term was coined trisomy 21. Although the chromosomes themselves are normal, the presence of an extra chromosome results in a variety of features well known and described as well as signs and symptoms of Down syndrome individuals.
Children with Down syndrome are usually smaller and their physical and mental development is slower than children without Down syndrome. His motor development is slower. Instead of walking between 12 and 24 months, usually learn to walk between 15 and 36 months. Language development also is markedly delayed.
Some physical characteristics of children with Down syndrome are a flattening of the back of the head, a tilt of the eyelids, small skin folds on the inner corner of the eyes, depressed nasal bridge, slightly smaller ears, mouth small, low muscle tone, loose ligaments, and small hands and feet.