Down syndrome is also known as Trisome 21. Everyone has 24 pairs of chromosomes 1 from the mom and 1 from the dad in each pair.
Sometimes an egg or a sperm has a 2nd copy of the #21 chromosome and when it's fertilized it results in trisome 21 or 3 copies of the #21 chromosome.
Trisome 21 has multiple health problems associated with it. Heart defects are very common in about %40 of babies with down syndrome. Hearing problems and eye problems are common also. %90 of pregnancies diagnosed with trisome 21 are terminated. Advanced maternal age is also a contributing factor and once a woman is 35 years old or older her chances of having a baby with down syndrome go up from about 1:1200 to about 1:400 and higher.
%80 of cases of down syndrome are born to moms UNDER 35 because we have more babies. I am 23 years old and my son TJ was born when I was 21. he has down syndrome.
There is also a type of down syndrome known as Mosaic down syndrome. There are 3 copies of the #21 chromosome in only some of the cells. This happens because the 3rd copy happens as a spontaneous mutation, and Mosaic down syndrome is thought to be less severe than standard down syndrome.
There's a 3rd type that causes down syndrome and it's known as a Translocation. usually it's where an extra piece of the #21 chromosome is found attached to #14 chromosome. A person can have a balanced translocation and they will appear normal but if genetic testing is done they'll find the extra piece of #21 attached to 14 and a piece of 14 attached to 21. These ppl have I think a %25 chance of having a baby with down syndrome.
I hope this answers your question.
to make it simple. Down syndrome is where a person has an extra piece of DNA in every cell in their body. It happens before birth and nothing the mom or dad does causes it. drugs cant cause it. people with down syndrome have almond shaped eyes, and shorter fingers. Alot of the time they don't have a nasal bone so they end up with a "button" nose.
those are just a couple of the differences down syndrome causes.
While the above post is mostly correct (thank you Martikadragoon!!) - In Down syndrome the person has 47 chromosomes instead of the usual 46 which come from 23 pairs of genes (half of which come from mom and other half from dad) the 21st pair has an extra copy (thus the name Trisomy 21). If you research "Down syndrome chromosome chart" you will be able to see this more clearly. People who have Ds usually have certain characteristics, but not everyone has the same ones, but they are common in most. There are different types of Down syndrome or Ds for short. Around 93% have Trisomy 21 which is typically random. 4% have what is called Translocation which is where a piece of genetic material breaks off and attach itself to other genes. 3% has whats called Mosaic Ds which is where not all the cells have the extra material, and sometimes because of this the features are less prominent.
I recommend you visit the Down syndrome group here: http://www.medhelp.org/forums/Down-syndrome/show/749 (not this community) because I have posted several help files and reference information you may find very handy.
If you have any other questions, please feel free to message me or visit our group for help!
Sandi (Down syndrome Group Founder) aka Dragon1973
The poster sent me a PM, and as it turns out, he explained that MTP stands for Termination. (Medical Termination of Pregnancy) So, the are researching for future pregnancies. It's unfortunate, but I don't think that the doctors gave her much choice, and likely didn't explain Ds in a favourable light. (They are in India.) They were concerned about the future of having more children with Ds, and if her risk increases or if it is a genetic problem for her.
Hopefully what we posted will help them in future!
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