Mosaic Down Syndrome

Get the Facts

Mosaic Down syndrome happens when a person has a percentage of their cells with an extra cell in their 21st chromosome that causes Down syndrome. The remainder of the cells in their body are normal. This type of Down syndrome accounts for about 2%-4% of the cases of Down syndrome.

Mosaic translocation Down syndrome occurs when a person has a percentage of translocation Down syndrome cells and the remaining cells are unaffected. Translocation happens when a piece of chromosome 21 becomes attached to another chromosome, during cell division. Translocation can be inherited by parents, but this is not always the case. This type of Down syndrome has not yet been studied, so we are unable to give an accurate number of occurrences.

According to research approximately 100-200 babies are born each year in America with mosaic Down syndrome. Due to lack of extensive international research, we are unable to confirm numbers for other countries but can assume that these numbers are similar in each country.

Because people with MDS often do not present the strong physical characteristics or delays present in Down syndrome, many live their lives without ever knowing they have this condition. In 2006, approximately 14,000 people in America have the diagnosis of MDS.

Nothing at all! Mosaic Down syndrome happens during cell division before and/or after conception. You did nothing to cause this to happen.

The old saying, “You can't judge a book by its cover” rings true here. You can not determine your child's abilities by the physical Down syndrome characteristics they present.
Depending on where the affected cells are located in the body and how many cells there are will determine how your child is affected.

The majority of people with MDS develop at a faster rate than those with Ds. Some do not experience any developmental delays while others have extreme delays in one or more areas.
The majority of children with MDS require special therapy. Your child may have developmental delays with speech, fine and gross motor skills. With the help of Speech, Occupational, and Physical Therapists, your child's delays can be helped and often he/she will overcome these delays
Some children require special education once they reach school age. Most children are “mainstreamed” in regular education classrooms leaving for extra support in academic areas. But, some children with MDS require no special education at all!
There is no way to determine how your child will be affected. With time, you will be able to see his/her strengths and if there is a delay you will be able to help your child with appropriate teaching and therapy.

Because children with MDS have a percentage of affected cells in their body, they can have the same health concerns of a person with Ds.
It is important to talk with your doctor about having scheduled Down syndrome health check-ups as described by the DSMIG

No one can tell you what your child will grow up to be! People with mosaic Down syndrome can grow up to be very productive citizens! They have jobs, and families, fun and friends. They have the same feelings as anyone and the same ambitions of their peers.

Expect the very best from your child and your child will give you their very best! Give them the love and attention that every child needs and enjoy them for who they are. Mosaic Down syndrome is not WHO your child is - it is WHAT your child has.

In this article MDS pertains to both forms of mosaic Down syndrome. (MDS & MTDS)

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