Happy World Down Syndrome Day! (and, Welcome to the T-21 Blog Hop! )

Today is World Down Syndrome Day.

Although it has been celebrated for 7 years, this is the first year that it will be recognized by the United Nations.  This date (3-21) was chosen to reflect Trisomy 21, the third or extra copy of the 21st chromosome that causes Down Syndrome.

For our inaugural post of the T-21 Blog Hop, and in honour of World Down Syndrome Day, I chose E for educate (to learn more about the Blog Hop, click here).  For those that don't know or possibly need a refresher, here is a quick synopsis of Down Syndrome or Trisomy 21. 

What is Down Syndrome?

Trisomy 21 or Down Syndrome is a genetic disorder caused by an accident in cell division.  This causes the creation of an extra copy of the 21st chromosome.  There are three different types of Down Syndrome:

Trisomy 21, where there is simply and extra copy of the 21st Chromosome.

Mosaic Down Syndrome where the creation of the extra chromosome happens later, causing some cells in the body to have it and others not.

Translocation, where a piece of the 21st chromosome breaks off and attaches itself to another (usually the 14th) which causes the same symptoms.

The extra genetic material can express itself in a variety of ways, including the stereotypical facial features and heart issues that many individuals experience.

Fast Facts about Down Syndrome:

• Occurs in Approximately 1:700 births and is the most common chromosomal disorder.
• Is independent of race, religion, creed, colour, socioeconomic status or nationality
• Occurs independently of any maternal or paternal activity prior to conception and pregnancy
• Maternal age can be a factor, although 80% of children with Trisomy 21 are born to woman under 35.  

Recent studies with families of individuals with DS have shown:

• 99% said they loved their son or daughter
• 97% of parents said they were proud of their son or daughter, 94% of siblings reported being proud of their brother or sister with DS
• 79% said their lives were made more positive by their son or daughter with DS
• 88% of siblings felt that they were better people because of their younger sibling with DS

People with Down Syndrome:

• Attend school, even post secondary
• Participate in the major decisions that affect their lives
• Contribute to society in meaningful and productive ways
• Flourish with a stimulating home environment, enriched educational programs, positive family support and good health care.

People with Down Syndrome exist in every culture, every country, every corner of the Earth.  Today we come together to celebrate and spread awareness.  Today we show the world lives of value and of worth. 

Welcome to my blog hop,  welcome to my global table.  Share your stories of support, motivation, inspiration, love and eduction.  If you do not have a blog of your own, submit your story in the comments below and/or Down Wit Dat's Facebook Page.  We meet under a banner of inclusion to foster acceptance.

For today at least, the old adage does hold:  SMILE... and the world smiles with you.

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Don't forget to vote for Down Wit Dat as About.com's Reader's Choice for Special Needs Parenting Blog. You can vote until the end of today using an email address or signing in through Facebook. VOTE HERE. Thanks to all who have participated and good luck to the other finalists! --Jxox

Types of Down Syndrome

"Down syndrome is just Down syndrome, right?"

"Some people have a mild case of it.  Like your boy..."

"He doesn't look like he has it... maybe the doctors are wrong"

(Random things people have said to me)

Today's Medical Monday is about the different types of Down syndrome.  As it turns out, not all instances of Down syndrome are exactly the same like my one friend there would like to think. As well, there is no such thing as a "mild case";  it is like being pregnant, you either are or you aren't.  There are three different types of Down syndrome.  In order to explain them properly, I am going to have to explain a few things in technical terms.  So buckle up friends, here comes the science...

You have 46 chromosomes (bundles of genes) in each of your cells.  Half of these you received from your mother and half from your father.   The exception to this are sex or germ cells (the ova or egg in the female and spermatozoa or sperm cells in the male) which only have half that amount (23) as they will hopefully combine with another sex cell and together make up the full amount.  Those cells with 46 chromosomes are referred to as diploid cells while those with 23 chromosomes are called haploid cells. 

A diploid cell will divide in order to make haploid cells;  this is called meiosis. It will first duplicate the genetic material and then sort out which came from where (Mom or Dad).  Some genes are swapped around at this stage which increases genetic diversity (Mom's blue eyes go in the Dad pile of genes while Dad's brown eyes go in the Mom pile, that kind of thing).  Now that there are two piles of mixed up DNA containing 46 chromosomes each, those two piles will divide into four haploid daughter cells.  During this last division, sometimes things do not go smoothly and things are divided unevenly (try ripping a dinner roll evenly in half and see if you do not have a new respect for cellular division). Sometimes one cell goes away with more information or an extra chromosome than the other one.  This is called nondisjunction.  There are many disorders that are a result of nondisjunction;  Down syndrome is just one of them.

Trisomy 21

When one of the cells comes away from meiosis with an extra copy of the 21st chromosome, it is called Trisomy 21. Every cell of the resulting zygote (and eventually, fetus) will have an extra copy of the gene and the results will be the characteristics of Down syndrome.  95% of the time, this is what happens.

This is what Wyatt has.

Translocation

Somewhere around 3-4% of the time, translocation occurs.  This is where a piece of a 21st chromosome breaks off during meiosis and attaches itself to another chromosome (usually #14).  This extra bit of #21, although attached to #14, causes the characteristics of Down syndrome to occur.  When this occurs, one of the parents is usually carrying chromosomes that are arranged unusually.

Mosaicism (or Mosaic Down syndrome)

This happens in 1-2 percent of DS cases.  The nondisjunction takes place after fertilization which creates some cells with an extra copy of chromosome 21 and some without.  How many cells have 47 chromosomes and how many have the normal 46 will determine how much and where the Down syndrome characteristics will be expressed.

Karyotype of a male with Trisomy 21