Cause
Down’s Syndrome is a genetic condition. It is the result of extra genetic material included within an individual’s cells.
Within each human cell there is 46 chromosomes, people with Down's syndrome have 47 chromosomes.
Dr. John Langdon Down first described the syndrome in the 1860s, the syndrome was named after him. It is important to remember that Down’s syndrome is a genetic condition not an illness or disease and the treatment of the individual should reflect this.
There are three types of Down’s syndrome
Trisomy 21
95 % of individuals with Down’s syndrome have this type of Down syndrome. The chromosome that is replicated a third time is chromosome 21.
Mosaic Down's syndrome
1% – 2% of individual’s with Down syndrome have this type of Down syndrome. Only some cells in the individual’s body have the extra chromosome 21. The characteristics of the syndrome can be less obvious in this type.
Translocation Down's syndrome
3%-4% of individuals with Down's syndrome have this type of Down’s syndrome. Translocation Down's syndrome is sometime hereditary. In this type the extra genetic material is translocated to other chromosome. It does not significantly affect the characteristics.
Within each human cell there is 46 chromosomes, people with Down's syndrome have 47 chromosomes.
Dr. John Langdon Down first described the syndrome in the 1860s, the syndrome was named after him. It is important to remember that Down’s syndrome is a genetic condition not an illness or disease and the treatment of the individual should reflect this.
There are three types of Down’s syndrome
Trisomy 21
95 % of individuals with Down’s syndrome have this type of Down syndrome. The chromosome that is replicated a third time is chromosome 21.
Mosaic Down's syndrome
1% – 2% of individual’s with Down syndrome have this type of Down syndrome. Only some cells in the individual’s body have the extra chromosome 21. The characteristics of the syndrome can be less obvious in this type.
Translocation Down's syndrome
3%-4% of individuals with Down's syndrome have this type of Down’s syndrome. Translocation Down's syndrome is sometime hereditary. In this type the extra genetic material is translocated to other chromosome. It does not significantly affect the characteristics.
While the cause of this error in cell division is unknown, a factor that is known to increase the chance of having a child with Down's syndrome is the maternal age. At the age of 35 the risk of having a baby with Down's syndrome increases to 1 in 400 babies.
Down’s syndrome is a chromosomal disorder caused by an error in cell division. This results in an extra copy of part of or all of chromosome 21. Cells now have 47 chromosomes instead of 46.
The graph below illustrates the increased the risk of Down's syndrome occurring as maternal age increases