Down syndrome (trisomy 21) is the most common diagnosable form of developmental disabilities. There are three types and they include: non disjunction, translocation and mosaicism. Though they all have almost similar features.
Most people have 23 pairs of chromosomes, for a total of 46. But a baby with down syndrome has an extra chromosome [47 instead of 46]. This extra genetic material causes problems with the way their bodies develop.
Physical features of children with down syndrome include: a short, stocky stature with a small head and flattening of the back and of the face. The nose is recessed and there is an upward slant of the eyes, a simian crease in the palms and general low muscle tone which may delay milestones.
They may have medical problems too, such as heart defects,leukemia, vision, hearing problems and orthopedic problems in fact they have a higher incidence of lung and respiratory tract infection and digestion problems like constipation. It could occur with autism.
Down syndrome can be identified during pregnancy by prenatal screening followed by diagnostic testing, or after birth by direct observation.In the U.S and other developed countries,since the introduction of screening,pregnancies with the diagnosis are terminated.
Kids with Down syndrome tend to grow and develop more slowly than other kids do.They may start crawling,walking or talking later than other babies.special help,like Occupational Therapy,physical Therapy and Speech Therapy,can give kids a push with their walking and talking skills.
The average IQ of a young adult with Down Syndrome is 50,equivalent to the mental age of a 9-10 year old child,but this varies widely.
Therapy and education has been shown to improve quality of life.Some children with Down Syndrome are usually streamlined while others need more of one-on-one specialized Montessori like education,some actually graduate from high school and even post secondary school education.
Life expectancy is around 50-60 years with proper medical care.