What is Down Syndrome?
In every cell in the human body there is a nucleus, where genetic material is stored in genes. Genes carry the codes responsible for all of our inherited traits and are grouped along rod-like structures called chromosomes. Typically, the nucleus of each cell contains 23 pairs of chromosomes, half of which are inherited from each parent. Down syndrome occurs when an individual has a full or partial extra copy of chromosome 21.
Down syndrome varies in severity among individuals, causing lifelong intellectual disability and developmental delays. It’s the most common genetic chromosomal disorder and cause of learning disabilities in children. It also commonly causes other medical abnormalities, including heart and gastrointestinal disorders.
What Causes Down Syndrome?
The cause of the extra full or partial chromosome is still unknown. Maternal age is the only factor that has been linked to an increased chance of having a baby with Down syndrome resulting from nondisjunction or mosaicism. However, due to higher birth rates in younger women, 80% of children with Down syndrome are born to women under 35 years of age.
There is no definitive scientific research that indicates that Down syndrome is caused by environmental factors or the parents’ activities before or during pregnancy. The additional partial or full copy of the 21st chromosome which causes Down syndrome can originate from either the father or the mother. Approximately 5% of the cases have been traced to the father. Down syndrome continues to be the most common chromosomal disorder. About 1 in every 700 babies is born with down syndrome. Between 1979 and 2003, the number of babies born with Down syndrome increased by about 30%.
Each person with Down syndrome is an individual — intellectual and developmental problems may be mild, moderate or severe. Some people are healthy while others have significant health problems such as serious heart defects.
Children and adults with Down syndrome have distinct facial features. Though not all people with Down syndrome have the same features, some of the more common features include:
– Flattened face
– Small head
– Short neck
– Protruding tongue
– Upward slanting eye lids (palpebral fissures)
– Unusually shaped or small ears
– Poor muscle tone
– Broad, short hands with a single crease in the palm
– Relatively short fingers and small hands and feet
– Excessive flexibility
– Tiny white spots on the colored part (iris) of the eye called Brushfield’s spots
– Short height