A chromosomal disorder caused by anerror in cell division that results in an extra21st chromosome.
Down syndrome occurs because of anabnormality characterized by an extracopy of genetic material on all or part ofthe 21st chromosome. Every cell in the bodycontains genes that are grouped alongchromosomes in the cell's nucleus or center.There are normally 46 chromosomes ineach cell, 23 inherited from your motherand 23 from your father. When some or allof a person's cells have an extra full orpartial copy of chromosome 21, the result isDown syndrome.
Physical characteristics include:
Eyes that have an upward slant, obliquefissures, epicanthic skin folds on the innercorner, and white spots on the iris
Low muscle tone
Small stature and short neck
Flat nasal bridge
Single, deep creases across the center of thepalm
Protruding tongue
Large space between large and second toe
A single flexion furrow of the fifth finger
Screening tests are used to estimate the riskthat a fetus has Down syndrome, anddiagnostic tests can tell whether the fetusactually has the condition. However, unlikediagnostic tests, screening tests cannot givedefinite answers as to whether the baby hasDown syndrome. Diagnostic tests, which are99% accurate in detecting Down syndromeand other problems, are usually performedinside the uterus and carry an extra risk ofmiscarriage, fetal injury, or preterm labor.
Nuchal translucency testing (at 11 to 14 weeks) - anultrasound that measures clear space in folds of tissuebehind the neck of a developing baby
Triple screen or quadruple screen (at 15 to 18 weeks)- measures the quantities of normal substances in themother's blood
Integrated screen - combines first trimester screeningtests (with or without nuchal translucency) and bloodtests with second trimester quadruple screen
Genetic ultrasound (at 18 to 20 weeks) - Detailedultrasound combined with blood test results
Chorionic villus sampling (at 8 to 12 weeks) -analysis of a tiny sample of placenta obtainedfrom a needle inserted into the cervix or theabdomen
Amniocentesis (at 15 to 20 weeks) - analysis ofa small amount of amniotic fluid obtained froma needle inserted into the abdomen
Percutaneous umbilical blood sampling (after20 weeks) - analysis of a small sample of bloodfrom the umbilical cord obtained from aneedle inserted into the abdomen
It is very important to stimulate,encourage, and educate children withDown syndrome from infancy. Programsfor young children with special needs areoffered in many communities. Earlyintervention programs, including physicaltherapy, occupational therapy, andspeech therapy can be very helpful.
Like all children, children with Down syndromegreatly benefit from being able to learn andexplore in a safe and supportive environment.Being included in family, community, andpreschool life will help a child with Downsyndrome develop to his or her full potential.
While social development and social learningare often quite good, development in otherareas such as motor skills, speech, andlanguage are usually delayed. Many childrenwith Down syndrome eventually reach mostdevelopmental milestones, but mild to severelearning difficulties will persist throughout life.
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http://www.nlm.nih.gov/medlineplus/downsyndrome.html