Week 8

Hello everyone!! I hope everyone had a splendid week!

This week was another interesting and exciting week on site with lots of new cases! But, for this blog post I’m gonna focus more on explaining what exome sequencing is, its benefits, and shortcomings.

Before I go into exome sequencing, I’m gonna define a few terms. There’s a real chance you guys will already know what this stuff means but just bear with me (is it bear or bare in this case? Whatever you know what I mean). I guess the best way to start going through this is at the base level, so an exon. Exons are segments of DNA which contain the necessary information for coding a protein. Exons create exomes which are the protein coding region of a genome, and a genome is the entire collection of genetic material.

Whole exome sequencing is the method by which protein coding regions (exons) of over 20,000 genes in the genome are sequenced. But, the exome only represents less than 2% of the genome. So at this point, I was curious about the other 98% of the genome - what if the variant lies there and that’s what is causing the disease? However, 85% of disease causing genetic variants are found in the exome section of the DNA. Since DNA is made up of introns and exons, and since the exons are responsible for protein coding and introns do not protein code, the mutations found in exons are often more harmful. By only sequencing and looking at the protein coding regions of the genome, researchers and clinicians are given a more manageable data set. A more focused and refined data set makes going through the data easier for the researchers and clinicians. Also, with this more focused approach, the researchers are more efficient while sifting through all the genetic variants, and determining which one might be causing the disease.

There are limitations to exome sequencing because it is still relatively new technology. The sequencing only proves to be successful around 25-40% of the time. The main reason for the percentage being so low is that even though 20,000 genes have been sequenced, many more genes still have to be discovered and there is always the possibility of the mutation being in the undiscovered genes. There are also issues with the technology used to sequence. Even though the technology is constantly changing and advancing, sometimes certain regions are too difficult to sequence, and also large deletions and duplications are not always picked up during testing.

However, the biggest success of genetic sequencing is that it can allow for a diagnosis to be made which will in turn lead to a more personalized, and effective treatment plan for the child. It can also be applied to family planning. After determining the disease the child has, parents are made aware of their risk of having another child with the same disorder. As a whole, sequencing helps the scientific community and allows for a greater understanding of rare disorders. Also, a lot of these diseases can be very emotionally taxing and many families have outreach programs that connect them to each other as a support system.

Ok, so that was a lot, but it’s all I’ve got for you guys this week. Surprisingly (or not so much I guess) it was pretty hard to find gifs that fit in with the context of this post, so hopefully this cute bunny makes up for it! See you guys next week!