Down syndrome (also called Trisomy 21) is a genetic disorder that occurs in approximately 1 of 800 live births. It is the leading cause of cognitive impairment. Down syndrome is associated with mild to moderate learning disabilities, developmental delays, characteristic facial features, and low muscle tone in early infancy. Many individuals with Down syndrome also have heart defects, leukemia, early-onset Alzheimer's disease, gastro-intestinal problems, and other health issues. The symptoms of Down syndrome range from mild to severe.
The only well known risk factor for conceiving a child with Down syndrome is advanced maternal age. The older the woman is at conception, the greater the risk of having a child with Down syndrome.
Mother's age at conception Risk of Down syndrome :
# 25 years 1 in 1,250
# 30 years 1 in 1,000
# 35 years 1 in 400
# 40 years 1 in 100
# 45 years 1 in 30
Parents who have conceived a child with Down syndrome have a 1% increased risk of conceiving another child with Down syndrome. If a parent is a carrier of a chromosome 21 translocation, the risk can be as high as 100%.
Women with Down syndrome have a 50% risk of conceiving a child with Down syndrome. If the father has Down syndrome, the risk of conceiving a child with Down syndrome is also increased.
Kindly,if you have any doubt about down syndrome, please have a look at this website : http://www.ds-int.org/