The human body carries our genetic codes that make up who we are. Genes are made of chromosomes that we inherit from our parents from conception. We get 23 pairs of chromosomes, half from our mother and the other half from our father. A baby with Down syndrome has a full or partial extra copy of chromosome 21, giving them 47 instead of 46 chromosomes.
The extra chromosome alters development and causes some common physical traits, including low muscle tone, small stature, an upward slant to the eyes, and a single deep crease across the center of the palm. Each person with Down syndrome is a unique individual and may possess a variety of these common characteristics.
There are 3 distinct forms of Down syndrome: Trisomy 21 (95% of all cases), Mosaicism (1% of all cases), and Translocation (4% of all cases). Each form of Down syndrome is distinct, but has one thing in common: the extra 21st chromosome. The difference is how the extra 21st chromosome attaches to the rest of the chromosomes in every gene of the body. But the characteristics remain similar in all forms.
According to NDSS:
“One in every 691 babies in the the United States is born with Down syndrome, making Down syndrome the most common genetic condition. Approximately 400,000 Americans have Down syndrome and about 6,000 babies with Down syndrome are born in the United States each year.”
There is no known “cause” of Down syndrome. It occurs in people of all races and economic levels. Maternal age is the only factor linked to the chance of having a baby with Down syndrome, although due to higher birth rates in younger women, the number of babies born to women under 35 years of age has increased. There is no scientific research to show environmental factors are a factor. The extra chromosome can come from either the mother or the father and there are some cases that have been traced to the father. The likelihood of a baby having Down syndrome increases with parental age, although it is not an absolute.
Most people with Down syndrome have mild to moderate cognitive delays. Despite the delays, individuals with down syndrome are becoming increasingly integrated into society. Due to advances in medical technology, they are living longer. Life expectancy has gone from age 9 in 1910 to over the age of 60 today because of advances such as corrective heart surgery. Because of increased life expectancy and social interaction, increased public awareness and acceptance of Down syndrome is becoming more important.