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A Little Lesson on Genetics

Our lives were turned upside down the day that Emarie came into our lives. But we would not have life any other way.... well maybe we could do without the constant surgeries and doctors appointments... but we'll take it for her!

Emarie was born with a very rare chromosome disorder that doesn't even have an official name it's so rare! It's called 18q Deletion Syndrome, which essentially means the q arm (long arm on the bottom) of one her 18th chromosomes is just not there. No rhyme or reason as to why it happened, meaning it didn't come from Steve or me. And to give you an idea of really how rare it is, we'll use the chromosome disorder most commonly known, Down Syndrome, which is a trisomy (or an extra copy) of chromosome 21. Down Syndrome happens in an estimated 1 in 400 births, so chances are most of us know of someone affected with Down's. Well, a Chromosome 18q deletion disorder happens in about 1 in 40,000 births, so chances are most have never heard of it. We hadn't until our little miss was born :)

Here's a picture to give you a better idea of how chromosome 18 looks. Starting at 11.1 to 11.32, this is considered the P arm. And from 11.2 to 23, this is considered the q arm.

21.31 is the most common breakpoint (where the deletion occurs) for q deletions, which is also Emarie's breakpoint. 

Other Chromosome 18 disorders that can occur include: 18p Deletion Syndrome (which is essentially the same as q deletion, but on the P arm ((shorter arm on top)) rather), Tetrasomy 18p (this one is essentially an extra chromosome but not a full trisomy, because they have 4 copies of the 18p arm, but the two extras form another chromosome), Ring 18 (most of these are missing both tips of the p and q arms, and for some reason unknown the chromosome forms a ring), then there's Trisomy 18 (a whole extra copy of chromosome 18, so three copies total). 

There's also other abnormalities that can occur, but these are the main.

To learn more about Chromosome 18 abnormalities click here

Or to visit any other Chromosome 18 family blogs, you can find a bunch listed to the left of this blog, under the section "Chromosome 18 Family Blogs"

Also, if you would like to read the story of Emarie's birth click here