What is Emma's chromosomal abnormality?

This post is to try and help people who would like a little deeper understanding about Emma's condition. It's a bit scientific, which isn't my (Katy's) forte, but I'll do my best!

Emma had a microarray test performed in December 2013. When we met with Emma's pediatric neurologist, I was pleased to hear that her genetic testing had "come back positive", until I realised that the word "positive" actually has a negative connotation when applied to these kind of tests. The actual result was:

arr[hg19] 13q34(110,945,681-111,279,310)x3

Confused? Yes, so was I... This is a steep learning curve.

Thankfully I have found "UNIQUE", an organization for rare chromosomal disorders. Please feel free to visit their website. There is a link to their site to the left hand side of this entry. UNIQUE explains it like this:  

The human body is made up of billions of individual cells. With the exception of the red blood cells, each of these cells contains a structure called the nucleus, which is held within a thick fluid called the cytoplasm. Inside the nucleus are found the chromosomes, which contain the genes. Genes are “strung” along the chromosomes, a bit like beads along a necklace. Genes are the instructions that tell the body how to develop and work properly. 

Apart from the mother’s egg cells or the father’s sperm cells, every cell in the human body normally contains 23 PAIRS of chromosomes, making 46 chromosomes in total in each cell... The first 22 pairs of chromosomes are called the autosomes and are numbered from 1 to 22 according to their length,starting with number 1 as the longest. The chromosomes in the 23rd pair are called the sex chromosomes, and are labelled X or Y.

This means that when we talk about Emma's disorder being at 13q34, the 13 is referring to the thirteenth pair of chromosomes. Parts of the autosomal chromosomes are referred to as being either "p" or "q", and this refers to the the fact that they have a "short arm" and a "long arm". So Emma's "long arm" of chromosome 13 is affected. The x3 means that there is a third copy of the part of the chromosome mentioned in the brackets.

We are awaiting the results of the next stage of the test, where they will try and get more specific to try and help us figure out exactly what this means in her genetic make-up, but at least we have a starting point, and, for me, the ability to brush up on some biology!

Please let me know if you have any questions... if Adam or I can't answer them, it would most likely be helpful for us to find out the answer. This is where having people along for the ride with us is incredibly helpful -- there is so much to think about, your questions may very well help us to focus on something we hadn't thought about before. We truly value your input!

With thanks,

Katy and Adam