For those of you who wants to learn more and want to take up some challenge, this section is for you! If you think that you have had enough and your brain can't absorb anymore info, you are free to skip this part! We are totally cool with it :)
Remember in the previous post I have mentioned that mutations causes the GAA gene to be defective? Well what exactly are these mutations? To date, there are more than 200 different type of mutations of the GAA gene recorded that causes Pompe. Some of these mutations are caused by substitution of amino acids while some are insertions or deletions. This can result in missense mutations which can totally change the function of the protein produced (in this case changes the function of acid alpha-glucosidase such that it does things that it wasn't originally supposed to do) or it can result in nonsense mutation where the polypeptide sequence is shorter than usual and it can't perform its function. As a result, the production of fully functioning acid alpha-glucosidase enzyme is greatly reduced, resulting in Pompe disease.
One common example of a substitution mutation in the GAA gene is the substitution of Glutamic acid for Aspartic acid at the codon 645. This mutation affects the post-translational modification of the acid alpha-glucosidase enzyme which results in the production of a non functional enzyme.
There are many many more such mutations that causes Pompe disease which makes it impossible to explain each and every one of it. However you've got the gist of it and I hope that this will encourage you to explore further ;)
(http://imindmaps.blogspot.sg/2013/10/mutations-in-dna.html) ~Mei Ying
References:
http://ghr.nlm.nih.gov/gene/GAA
http://www.pompe.com/healthcare-professionals/genetics-epidemiology/mutations.aspx
https://catalog.coriell.org/0/sections/Search/Sample_Detail.aspx?Ref=GM01935&product=CC
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